JP4472662B2 - Zoom lens and camera equipped with zoom lens and image sensor - Google Patents

Description

  The present invention relates to a zoom lens and a camera including a zoom lens and an electronic image sensor, and more particularly to a zoom lens suitable for a video camera or an electronic still camera using an electronic image sensor such as a CCD or CMOS.

  Conventionally, as a zoom lens suitable for a camera using an electronic image sensor, in Patent Document 1 or the like, from the object side, a first lens group having a negative power, a second lens group having a positive power, and a positive power The first lens group, the second lens group, and the third lens are configured by moving the first lens group and the second lens group on the optical axis. An optical system that performs zooming by changing the distance between groups has been proposed.

  On the other hand, in recent years, zoom lenses with high imaging performance, zoom lenses with a high zoom ratio, especially zoom lenses with a wide angle of view on the wide-angle side have been demanded due to an increase in the number of pixels of electronic image sensors such as CCD and CMOS. .

  In addition, the size of the image sensor itself and the increase in the number of pixels reduce the light receiving area of each pixel of the electronic image sensor, and a lens system with a brighter F number is required.

  There are proposals in Patent Document 2 and Patent Document 3 as proposals regarding the angle of view (2ω) on the wide angle side of about 60 ° to 67 °, the zoom ratio of about 3 times, and the F number of about 2. Dissatisfaction remains with respect to the wide angle of view and distortion at the wide-angle end. Patent Documents 4 and 5 have a wide angle of view (2ω) exceeding 70 °, but dissatisfaction remains with respect to the brightness of the F number. Moreover, the thing of patent document 6 and patent document 7 remains dissatisfied with a distortion aberration etc.

In general, as the angle of view is increased, it becomes difficult to correct off-axis aberrations, particularly distortion aberrations and lateral chromatic aberrations. Further, when the F number becomes bright, it becomes difficult to correct spherical aberration and coma.
Japanese Patent Laid-Open No. 7-261083 Japanese Patent Laid-Open No. 11-23967 JP 11-52246 A JP-A-11-174322 JP 10-39214 A JP 10-39214 A Japanese Patent Laid-Open No. 9-21950

  The present invention has been made in view of such a situation in the prior art, and its purpose is a zoom lens having a zoom ratio of about 3 times, a wide angle of view on the wide angle side, and a bright F number. A lens layout of a zoom lens capable of obtaining good imaging performance and a camera provided with such a zoom lens. Another object is to provide a lens layout considering manufacturability.

  The first zoom lens of the present invention that achieves the above-mentioned object, in order from the object side, is a first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens having a positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed and the distance between the first lens group, the second lens group, and the third lens group. The aperture is moved together with the second lens group at the time of zooming, and the first lens group is arranged in order from the object side, the negative lens, the negative lens, and the positive lens. The third lens group includes one lens, the first lens group includes a lens having an aspherical surface that satisfies the following conditional expression (1), and the third lens group satisfies the following condition: Having a lens with an aspheric surface that satisfies equation (2) A zoom lens according to claim.

0 <(1 / r _a1 −1 / r _m1 ) h ₁ / (n _a1 −n _a1 ′) <1 (1)
−1 <(1 / r _a3 −1 / r _m3 ) h ₃ / (n _a3 −n _a3 ′) <0 (2)
Where _ra1 is the paraxial radius of curvature of the aspheric surface I arranged in the first lens group, and _rm1 is the intersection of the aspheric surface I arranged in the first lens group with the optical axis on the aspheric surface I. The distance to the point on the optical axis at which the normal at the arbitrary point (1) between the maximum diameter of the on-axis light beam and the effective diameter including the off-axis light beam is closest to the optical axis, n _a1 is the aspherical surface I The refractive index on the object side, n _a1 ′ is the refractive index on the image side of the aspheric surface I, h ₁ is the height from the optical axis of the point (1), and ra ₃ is the aspheric surface arranged in the third lens group. The paraxial radius of curvature III, r _m3, is the effective diameter including the maximum diameter of the on-axis light beam on the aspheric surface III and the off-axis light beam from the intersection of the aspheric surface III arranged in the third lens group with the optical axis. Is the distance to the point on the optical axis at which the normal at the arbitrary point (3) between the two is closest to the optical axis, n _a3 is the refractive index on the object side of the aspheric surface III, and n _a3 ′ is the image side of the aspheric surface III Refractive index h ₃ is the height from the optical axis of the point (3).

  The operational effects of the first zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. Here, the term “shading” means that an image pickup device such as a CCD has an element structure, for example, a color filter or a light receiving portion located behind a light blocking portion of a charge transfer path, or a light blocking portion of a charge transfer path. When a light beam is obliquely incident on the element due to a micro lens or the like disposed on the object side of the object, a change in color tone (color shading) or a change in peripheral light amount (shading) occurs. These changes are the shading here. In order to avoid this shading problem, it is desirable that the exit pupil be far away.

  By making the third lens group one lens, it is possible to reduce the length of the third lens group on the optical axis, which is desirable for making the entire length compact.

  At this time, the third lens group does not greatly affect the deterioration of the aberration with respect to the axial light beam, but off-axis light beam, particularly astigmatism, is likely to occur. Depending on the performance of the image sensor and the like, it is possible to increase the imaging performance by increasing the number of constituent elements of the third lens group, but by arranging an aspheric surface that satisfies the conditional expression (2), It can be composed of a single positive lens. That is, by satisfying the conditional expression (2), the difference between the center thickness of the lens and the thickness of the peripheral portion can be reduced, and a high imaging performance such as an image sensor with a large number of pixels is required. The occurrence of point aberration can be reduced. If the upper limit of 0 in conditional expression (2) is exceeded, the effect of the aspherical surface will be lost, and astigmatism will not be suppressed. If the lower limit of -1 is exceeded, the substantial exit pupil position for off-axis light will be disadvantageous. This is not preferable because the off-axis light beam is incident from a direction greatly deviated from the vertical direction with respect to the imaging surface.

  Further, the outer diameter of the lens can be reduced by configuring the first lens group as a negative lens, a negative lens, and a positive lens and placing the negative lens component on the object side. Further, by dividing the negative lens into two, the occurrence of various aberrations can be reduced. In particular, the performance can be maintained by introducing an aspherical surface that satisfies the conditional expression (1) for distortion and coma aberration that imposes a burden on the first lens group due to widening and downsizing, and performance deteriorates. By satisfying conditional expression (1), it is desirable to balance the occurrence of aberrations related to off-axis light beams in the third lens group. Exceeding the lower limit of 0 to conditional expression (1) is undesirable because the aspherical effect is lost. Exceeding the upper limit of 1 is not preferable because aberration correction cannot be balanced in the entire lens system.

  The second zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When zooming is performed, the diaphragm moves together with the second lens group at the time of zooming, the third lens group is composed of one lens, and the conditional expression (3) is applied to the first lens group. A zoom lens using a lens in which an aspherical surface is formed by thinly applying a resin to the concave surface of a spherical lens satisfying the above.

−0.1 <(1 / r _a1 ′ −1 / r _m1 ) h ₁ / (n _a1 −n _a1 ′) <1
... (3)
Here, r _a1 ′ is the paraxial radius of curvature of the concave surface on which the resin forming the aspheric surface I arranged in the first lens group is applied, and r _m1 is the aspheric surface arranged in the optical axis and the first lens group. The distance from the intersection of I to the point on the optical axis at which the normal at the arbitrary point (1) between the maximum diameter of the axial light beam on the aspherical surface and the effective diameter including the off-axis light beam is closest to the optical axis , n _a1 is the refractive index of the object-side aspherical, n _a1 'is the refractive index of the image-side aspherical, h ₁ is the height from the optical axis of the point (1).

  The operational effects of the second zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact.

  Further, by introducing an aspherical surface that satisfies the conditional expression (1) for distortion and coma aberration that imposes a burden on the first lens group due to widening and downsizing, and the performance deteriorates, the performance can be maintained. At this time, it is desirable to use a lens in which an aspherical surface is formed by thinly applying a resin to the concave surface of the spherical lens because the aspherical surface can be easily formed, and it is particularly desirable to satisfy the conditional expression (3). . That is, by satisfying conditional expression (3), an aspherical surface for obtaining good imaging performance can be formed without greatly changing the thickness of the resin to be applied. If the thickness of the resin to be applied changes greatly, it is not preferable in terms of changes in performance due to changes in temperature and humidity, and ease of solidifying the resin during production. If the lower limit of -0.1 of conditional expression (3) is exceeded, the required aspheric performance cannot be obtained. When the upper limit of 1 is exceeded, the change in the thickness of the resin to be applied becomes large, which is not preferable. Note that the paraxial curvature radius of the concave surface to which the resin is applied and the paraxial curvature radius of the aspherical surface need not be equal, and may be determined from manufacturability and the like.

  The third zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When changing the magnification, the stop moves together with the second lens group. The first lens group starts from the negative side, air, negative lens, air, and positive lens in order from the object side. The third lens group includes a single lens, and the second lens group includes a positive lens, a positive / negative cemented lens, and a positive lens in order from the object side, and satisfies the following conditional expression (4): The zoom lens is characterized by that.

_{0.4 <f 3 / f t <} 2.5 ··· (4)
However, f ₃ is the focal length, f _t of the third lens group is a focal length of the entire system at the telephoto end.

  The operational effects of the third zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact.

  Further, the outer diameter of the lens can be reduced by configuring the first lens group as a negative lens, a negative lens, and a positive lens and placing the negative lens component on the object side. Further, by dividing the negative lens into two, the occurrence of various aberrations can be reduced. In particular, the distortion can be reduced by providing an air space between the three lenses instead of cementing them and having an independent radius of curvature.

  By constructing the second lens group in order from the object side, a positive lens, a positive and negative cemented lens, and a positive lens, spherical aberration and off-axis coma are generated by two positive lenses arranged near the aperture stop. The positive lens on the image side cooperates with the third lens group to control the off-axis aberration while keeping the exit pupil position away from the image plane, and the negative lens is imaged with the second positive lens from the object side. Chromatic aberration is controlled by placing it between the positive lenses on the side. Since this negative lens is the only negative lens on the image side from the aperture stop, the burden on aberration correction is large and the manufacturing error becomes severe. By joining this negative lens to the second positive lens, it is possible to make an optical system that is resistant to manufacturing errors, and to suppress the occurrence of higher-order aberrations between the second positive lens and the negative lens. Chromatic aberration can be effectively suppressed.

  By satisfying the conditional expression (4), it is possible to make the imaging performance and the exit pupil position suitable with a small number of constituent elements of the third lens group. If the upper limit is larger than 2.5, it is difficult to keep the exit pupil away while keeping the entire length short. If the lower limit is less than 0.4, the aberration generated in the third lens group becomes too large, and the performance cannot be maintained.

  The fourth zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When changing the magnification, the stop moves together with the second lens group. The first lens group starts from the negative side, air, negative lens, air, and positive lens in order from the object side. The third lens group includes one lens, and the second lens group includes, in order from the object side, a positive lens, a positive / negative cemented lens, and a positive lens, and satisfies the following conditional expression (5): The zoom lens is characterized by that.

1.2 <f _1-N / f _2-N <2.7 (5)
However, f _1-N is the focal length, f _2-N of the most object side concave in the first lens group is the focal length of the second concave from the object side of the first lens group.

  The effects of the fourth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact.

  Further, the outer diameter of the lens can be reduced by configuring the first lens group as a negative lens, a negative lens, and a positive lens and placing the negative lens component on the object side. Further, by dividing the negative lens into two, the occurrence of various aberrations can be reduced. In particular, the distortion can be reduced by providing an air space between the three lenses instead of cementing them and having an independent radius of curvature.

  By constructing the second lens group in order from the object side, a positive lens, a positive and negative cemented lens, and a positive lens, spherical aberration and off-axis coma are generated by two positive lenses arranged near the aperture stop. The positive lens on the image side cooperates with the third lens group to control the off-axis aberration while keeping the exit pupil position away from the image plane, and the negative lens is imaged with the second positive lens from the object side. Chromatic aberration is controlled by placing it between the positive lenses on the side. Since this negative lens is the only negative lens on the image side from the aperture stop, the burden on aberration correction is large and the manufacturing error becomes severe. By joining this negative lens to the second positive lens, it is possible to make an optical system that is resistant to manufacturing errors, and to suppress the occurrence of higher-order aberrations between the second positive lens and the negative lens. Chromatic aberration can be effectively suppressed.

  Conditional expression (5) defines the power ratio of the first lens and the second lens in the first lens group. In particular, the off-axis light beam on the wide angle side has a large incident angle with respect to the optical axis, and the incident angle on the first surface is also large. One of the functions of the first lens and the second lens is to moderate the angle of the luminous flux with respect to the optical axis at the four surfaces of the first lens and the second lens, but the conditional expression (5) is satisfied. Thus, this function can be more effectively operated. If the lower limit of the conditional expression (5) is less than 1.2, it is difficult to correct coma and astigmatism that occur in the most concave lens on the object side. If it is larger than the upper limit of 2.7, the aberration generated by the second concave lens from the object side becomes too large.

  The fifth zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When changing the magnification, the stop moves together with the second lens group. The first lens group starts from the negative side, air, negative lens, air, and positive lens in order from the object side. The third lens group includes one lens, and the second lens group includes a positive lens, a positive / negative cemented lens, and a positive lens in order from the object side, and satisfies the following conditional expression (6): The zoom lens is characterized by that.

2 <f ₃ / IH <12 (6)
Here, f ₃ is the focal length of the third lens group, and IH is the image height.

  The function and effect of the fifth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact.

  Further, the outer diameter of the lens can be reduced by configuring the first lens group as a negative lens, a negative lens, and a positive lens and placing the negative lens component on the object side. Further, by dividing the negative lens into two, the occurrence of various aberrations can be reduced. In particular, the distortion can be reduced by providing an air space between the three lenses instead of cementing them and having an independent radius of curvature.

  By constructing the second lens group in order from the object side, a positive lens, a positive and negative cemented lens, and a positive lens, spherical aberration and off-axis coma are generated by two positive lenses arranged near the aperture stop. The positive lens on the image side cooperates with the third lens group to control the off-axis aberration while keeping the exit pupil position away from the image plane, and the negative lens is imaged with the second positive lens from the object side. Chromatic aberration is controlled by placing it between the positive lenses on the side. Since this negative lens is the only negative lens on the image side from the aperture stop, the burden on aberration correction is large and the manufacturing error becomes severe. By joining this negative lens to the second positive lens, it is possible to make an optical system that is resistant to manufacturing errors, and to suppress the occurrence of higher-order aberrations between the second positive lens and the negative lens. Chromatic aberration can be effectively suppressed.

  If the lower limit of 2 of conditional expression (6) is exceeded, the refractive power of the third lens group becomes too strong with respect to the image height, and the difference between the center thickness of the positive lens constituting the third lens group and the peripheral thickness is large. Therefore, the occurrence of aberration of off-axis light flux is increased, which is not preferable. If the upper limit of 12 is exceeded, the refractive power of the third lens group becomes too weak with respect to the image height, and if the total length is kept short, the above-mentioned shading tends to occur at a high image height, which is not preferable.

  The sixth zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When changing the magnification, the stop moves together with the second lens group. The first lens group starts from the negative side, air, negative lens, air, and positive lens in order from the object side. The third lens group is composed of one lens, an aspherical surface satisfying conditional expression (7) is used for the most object side surface of the second lens group, and the following conditional expression (4) It is a zoom lens characterized by satisfying.

−1 <(1 / r _a2 −1 / r _m2 ) h ₂ / (1-n _a2 ′) <0 (7)
_{0.4 <f 3 / f t <} 2.5 ··· (4)
However, from the r _a2 paraxial curvature radius of the aspheric II which are arranged closest to the object side of the second lens unit r _{m @ 2} is the intersection of the aspherical II disposed on the optical axis and a second lens group, Up to the point on the optical axis where the normal at the arbitrary point (2) between the maximum diameter of the axial light beam on the aspherical surface 0.7 and the maximum diameter of the axial light beam is closest to the optical axis. Distance, n _a2 ′ is the refractive index of the lens disposed closest to the object side of the second lens group, h ₂ is the height of the point (2) from the optical axis, f ₃ is the focal length of the third lens group, f _t is the focal length of the entire system at the telephoto end.

  The operational effects of the sixth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact.

  Further, the outer diameter of the lens can be reduced by configuring the first lens group as a negative lens, a negative lens, and a positive lens and placing the negative lens component on the object side. Further, by dividing the negative lens into two, the occurrence of various aberrations can be reduced. In particular, it is possible to reduce the distortion by providing an air space between the three lenses instead of cementing them and having an independent radius of curvature.

  The most object-side surface of the second lens group is one surface on which the axial light beam spreads, and is also the surface through which the off-axis light beam passes near the optical axis. By arranging an aspheric lens on this surface, it is possible to reduce the occurrence of spherical aberration without affecting astigmatism or distortion.

  Conditional expression (7) defines the shape of the aspherical surface. If the lower limit of -1 is exceeded, spherical aberration becomes uncorrected, and if the upper limit of 0 is exceeded, the effect of the aspherical surface is small. This is not preferable because it is reflected in an excessively corrected state of the spherical lens.

  Further, by satisfying conditional expression (4), it is possible to optimize the imaging performance and the exit pupil position with a small number of constituent elements of the third lens group. If the upper limit is larger than 2.5, it is difficult to keep the exit pupil away while keeping the entire length short. If the lower limit is less than 0.4, the aberration generated in the third lens group becomes too large, and the performance cannot be maintained.

  The seventh zoom lens of the present invention includes, in order from the object side, a first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When changing the magnification, the stop moves together with the second lens group. The first lens group starts from the negative side, air, negative lens, air, and positive lens in order from the object side. The third lens group is composed of one lens, an aspherical surface satisfying conditional expression (7) is used for the most object side surface of the second lens group, and the following conditional expression (5) It is a zoom lens characterized by satisfying.

−1 <(1 / r _a2 −1 / r _m2 ) h ₂ / (1-n _a2 ′) <0 (7)
1.2 <f _1-N / f _2-N <2.7 (5)
However, from the r _a2 paraxial curvature radius of the aspheric II which is disposed on the most object side in the second lens group, r _{m @ 2} is the intersection of the aspherical II disposed on the optical axis and the second lens group, Up to the point on the optical axis where the normal at the arbitrary point (2) between the maximum diameter of the axial light beam on the aspherical surface 0.7 and the maximum diameter of the axial light beam is closest to the optical axis. The distance, n _a2 ′ is the refractive index of the lens located closest to the object side of the second lens group, h _{2 is} the height of the point (2) from the optical axis, and f _1-N is the most of the first lens group The focal length of the concave lens on the object side, f _2-N is the focal length of the second concave lens from the object side of the first lens group.

  The operational effects of the seventh zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact.

  Further, the outer diameter of the lens can be reduced by configuring the first lens group as a negative lens, a negative lens, and a positive lens and placing the negative lens component on the object side. Further, by dividing the negative lens into two, the occurrence of various aberrations can be reduced. In particular, it is possible to reduce the distortion by providing an air space between the three lenses instead of cementing them and having an independent radius of curvature.

  The most object-side surface of the second lens group is one surface on which the axial light beam spreads, and is also the surface through which the off-axis light beam passes near the optical axis. By arranging an aspheric lens on this surface, it is possible to reduce the occurrence of spherical aberration without affecting astigmatism or distortion.

  Conditional expression (7) defines the shape of the aspherical surface. If the lower limit of -1 is exceeded, spherical aberration becomes uncorrected, and if the upper limit of 0 is exceeded, the effect of the aspherical surface is small. This is not preferable because it is reflected in an excessively corrected state of the spherical lens.

  Conditional expression (5) defines the power ratio of the first lens and the second lens in the first lens group. In particular, the off-axis light beam on the wide angle side has a large incident angle with respect to the optical axis, and the incident angle on the first surface is also large. One of the functions of the first lens and the second lens is to moderate the angle of the luminous flux with respect to the optical axis at the four surfaces of the first lens and the second lens, but the conditional expression (5) is satisfied. Thus, this function can be more effectively operated. If the lower limit of the conditional expression (5) is less than 1.2, it is difficult to correct coma and astigmatism that occur in the most concave lens on the object side. If it is larger than the upper limit of 2.7, the aberration generated by the second concave lens from the object side becomes too large.

  The eighth zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When changing the magnification, the stop moves together with the second lens group. The first lens group starts from the negative side, air, negative lens, air, and positive lens in order from the object side. The third lens group is composed of one lens, an aspherical surface satisfying conditional expression (7) is used for the most object side surface of the second lens group, and the following conditional expression (6) It is a zoom lens characterized by satisfying.

−1 <(1 / r _a2 −1 / r _m2 ) h ₂ / (1-n _a2 ′) <0 (7)
2 <f ₃ / IH <12 (6)
However, from the r _a2 paraxial curvature radius of the aspheric II which is disposed on the most object side in the second lens group, r _{m @ 2} is the intersection of the aspherical II disposed on the optical axis and the second lens group, Up to the point on the optical axis where the normal at the arbitrary point (2) between the maximum diameter of the axial light beam on the aspherical surface 0.7 and the maximum diameter of the axial light beam is closest to the optical axis. Distance, n _a2 ′ is the refractive index of the lens disposed closest to the object side of the second lens group, h ₂ is the height of the point (2) from the optical axis, f ₃ is the focal length of the third lens group, IH is the image height.

  The operational effects of the eighth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact.

  Further, the outer diameter of the lens can be reduced by configuring the first lens group as a negative lens, a negative lens, and a positive lens and placing the negative lens component on the object side. Further, by dividing the negative lens into two, the occurrence of various aberrations can be reduced. In particular, it is possible to reduce the distortion by providing an air space between the three lenses instead of cementing them and having an independent radius of curvature.

  The most object-side surface of the second lens group is one surface on which the axial light beam spreads, and is also the surface through which the off-axis light beam passes near the optical axis. By arranging an aspheric lens on this surface, it is possible to reduce the occurrence of spherical aberration without affecting astigmatism or distortion.

  Conditional expression (7) defines the shape of the aspherical surface. If the lower limit of -1 is exceeded, spherical aberration becomes uncorrected, and if the upper limit of 0 is exceeded, the effect of the aspherical surface is small. This is not preferable because it is reflected in an excessively corrected state of the spherical lens.

  If the lower limit of 2 of the conditional expression (6) is exceeded, the refractive power of the third lens group becomes too strong with respect to the image height, and the difference between the center thickness of the positive lens constituting the third lens group and the peripheral thickness is increased. Is undesirably large because of increasing aberration of off-axis light flux. If the upper limit of 12 is exceeded, the refractive power of the third lens group becomes too weak with respect to the image height, and if the total length is kept short, the above-mentioned shading tends to occur at a high image height, which is not preferable.

  The ninth zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When the magnification is changed, the diaphragm moves together with the second lens group, and all the lenses constituting the first lens group are meniscus lenses that are convex on the object side, and A zoom lens characterized by satisfying a conditional expression.

1.2 <f _1-N / f _2-N <2.7 (5)
However, f _1-N is the focal length, f _2-N of the most object side concave in the first lens group is the focal length of the second concave from the object side of the first lens group.

  The operational effects of the ninth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact. In particular, the off-axis light beam on the wide-angle side has a large incident angle with respect to the optical axis, and the incident angle on the first surface is also large. By using a meniscus lens as the constituent lens of the first lens group, the light beam of this light beam can be bent little by little on each surface, and the amount of aberration generated can be suppressed small.

  In particular, if the power ratio between the first lens and the second lens is defined so as to satisfy the conditional expression (5), this effect can be more exerted, which is preferable. If the lower limit of the conditional expression (5) is less than 1.2, it is difficult to correct coma and astigmatism that occur in the most concave lens on the object side. If it is larger than the upper limit of 2.7, the aberration generated by the second concave lens from the object side becomes too large.

  The tenth zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When the magnification is changed, the diaphragm moves together with the second lens group, and all the lenses constituting the first lens group are meniscus lenses that are convex on the object side, and A zoom lens satisfying conditional expression (8).

-1.35 <f ₁ / f ₃ <−0.4 (8)
Here, f ₁ is the focal length of the first lens group and f ₃ is the focal length of the third lens group.

  The operational effects of the tenth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact. In particular, the off-axis light beam on the wide-angle side has a large incident angle with respect to the optical axis, and the incident angle on the first surface is also large. By using a meniscus lens as the constituent lens of the first lens group, the light beam of this light beam can be bent little by little on each surface, and the amount of aberration generated can be suppressed small.

  Conditional expression (8) defines a preferable condition for moving the exit pupil away while maintaining a high zoom ratio and a wide angle of view. If the upper limit is larger than −0.4, the aberration in the first lens group is defined. The amount generated is too large. If it is smaller than the lower limit of -1.35, it is impossible to achieve both a high zoom ratio and miniaturization.

  The eleventh zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When zooming, the diaphragm moves integrally with the second lens group, the third lens group is composed of one lens, and the second lens group is in order from the object side. A zoom lens comprising a positive lens, a positive / negative cemented lens, and a positive lens, wherein an aspherical surface satisfying conditional expression (7) is used as the most object side surface of the second lens group.

−1 <(1 / r _a2 −1 / r _m2 ) h ₂ / (1-n _a2 ′) <0 (7)
However, from r _a2 paraxial curvature radius of the aspheric II which is disposed on the most object side in the second lens group, r _{m @ 2} is the intersection of the aspherical II disposed on the optical axis and the second lens group, Up to the point on the optical axis where the normal at the arbitrary point (2) between the maximum diameter of the axial light beam on the aspherical surface 0.7 and the maximum diameter of the axial light beam is closest to the optical axis. The distance, n _a2 ′, is the refractive index of the lens arranged closest to the object side in the second lens group, and h ₂ is the height from the optical axis of the point (2).

  The operational effects of the eleventh zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact. By constructing the second lens group in order from the object side, a positive lens, a positive and negative cemented lens, and a positive lens, spherical aberration and off-axis coma are generated by two positive lenses arranged near the aperture stop. The positive lens on the image side cooperates with the third lens group to control the off-axis aberration while keeping the exit pupil position away from the image plane, and the negative lens is imaged with the second positive lens from the object side. Chromatic aberration is controlled by placing it between the positive lenses on the side. Since this negative lens is the only negative lens on the image side from the aperture stop, the burden on aberration correction is large and the manufacturing error becomes severe. By joining this negative lens to the second positive lens, it is possible to make an optical system that is resistant to manufacturing errors, and to suppress the occurrence of higher-order aberrations between the second positive lens and the negative lens. Chromatic aberration can be effectively suppressed. Further, the surface closest to the object side of the second lens group is a surface on which the axial light beam spreads, and is also a surface through which the off-axis light beam passes near the optical axis. By arranging an aspheric lens on this surface, the generation of spherical aberration can be reduced without affecting astigmatism, distortion, and the like.

  Conditional expression (7) defines the shape of the aspherical surface. If the lower limit of -1 is exceeded, spherical aberration becomes uncorrected, and if the upper limit of 0 is exceeded, the effect of the aspherical surface is small. This is not preferable because it is reflected in an excessively corrected state of the spherical lens.

  The twelfth zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When zooming, the diaphragm moves integrally with the second lens group, the third lens group is composed of one lens, and the second lens group is in order from the object side. It is composed of a positive lens, a positive / negative cemented lens, and a positive lens, and the lens closest to the image plane in the second lens group is a meniscus lens convex to the image plane side, and satisfies the following conditional expression (9): It is a zoom lens.

2.7 <Σ _2g /IH<4.7 (9)
However, Σ _2g is the distance on the optical axis from the aperture stop to the surface closest to the image plane of the second lens group, and IH is the image height.

  The effects of the twelfth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact. By constructing the second lens group in order from the object side, a positive lens, a positive and negative cemented lens, and a positive lens, spherical aberration and off-axis coma are generated by two positive lenses arranged near the aperture stop. The positive lens on the image side cooperates with the third lens group to control the off-axis aberration while keeping the exit pupil position away from the image plane, and the negative lens is imaged with the second positive lens from the object side. Chromatic aberration is controlled by placing it between the positive lenses on the side. Since this negative lens is the only negative lens on the image side from the aperture stop, the burden on aberration correction is large and the manufacturing error becomes severe. By joining this negative lens to the second positive lens, it is possible to make an optical system that is resistant to manufacturing errors, and to suppress the occurrence of higher-order aberrations between the second positive lens and the negative lens. Chromatic aberration can be effectively suppressed. Further, by making the lens closest to the image plane in the second lens group a meniscus lens convex toward the image plane, fluctuations in coma and chromatic aberration during zooming can be reduced.

  On the other hand, if the upper limit of the conditional expression (9) is larger than 4.7, the total length of the telephoto end and the total length when retracted become large, which is not preferable. If it is smaller than the lower limit of 2.7, the aberration generated in the second lens group becomes large, which is not preferable.

  The thirteenth zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When zooming, the diaphragm moves integrally with the second lens group, the third lens group is composed of one lens, and the second lens group is in order from the object side. It is composed of a positive lens, a positive / negative cemented lens, and a positive lens, and the lens closest to the image plane in the second lens group is a meniscus lens convex to the image plane side, and satisfies the following conditional expression (4): It is a zoom lens.

_{0.4 <f 3 / f t <} 2.5 ··· (4)
However, f ₃ is the focal length, f _t of the third lens group is a focal length of the entire system at the telephoto end.

  The effects of the thirteenth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact. By constructing the second lens group in order from the object side, a positive lens, a positive and negative cemented lens, and a positive lens, spherical aberration and off-axis coma are generated by two positive lenses arranged near the aperture stop. The positive lens on the image side cooperates with the third lens group to control the off-axis aberration while keeping the exit pupil position away from the image plane, and the negative lens is imaged with the second positive lens from the object side. Chromatic aberration is controlled by placing it between the positive lenses on the side. Since this negative lens is the only negative lens on the image side from the aperture stop, the burden on aberration correction is large and the manufacturing error becomes severe. By joining this negative lens to the second positive lens, it is possible to make an optical system that is resistant to manufacturing errors, and to suppress the occurrence of higher-order aberrations between the second positive lens and the negative lens. Chromatic aberration can be effectively suppressed. Further, by making the lens closest to the image plane in the second lens group a meniscus lens convex toward the image plane, fluctuations in coma and chromatic aberration during zooming can be reduced.

  By satisfying the conditional expression (4), it is possible to make the imaging performance and the exit pupil position suitable with a small number of constituent elements of the third lens group. If the upper limit is larger than 2.5, it is difficult to keep the exit pupil away while keeping the entire length short. If the lower limit is less than 0.4, the aberration generated in the third lens group becomes too large, and the performance cannot be maintained.

  The fourteenth zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When zooming, the diaphragm moves integrally with the second lens group, the third lens group is composed of one lens, and the second lens group is in order from the object side. The second lens group includes a positive lens, a positive and negative cemented lens, and a positive lens. The most image side lens of the second lens group is a meniscus lens convex to the image side, and at least two lenses from the most object side of the first lens group. Is a negative lens, and the following conditional expression ( ) Is a zoom lens and satisfies the.

1.2 <f _1-N / f _2-N <2.7 (5)
However, f _1-N is the focal length, f _2-N of the most object side concave in the first lens group is the focal length of the second concave from the object side of the first lens group.

  The operational effects of the fourteenth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact. By constructing the second lens group in order from the object side, a positive lens, a positive and negative cemented lens, and a positive lens, spherical aberration and off-axis coma are generated by two positive lenses arranged near the aperture stop. The positive lens on the image side cooperates with the third lens group to control the off-axis aberration while keeping the exit pupil position away from the image plane, and the negative lens is imaged with the second positive lens from the object side. Chromatic aberration is controlled by placing it between the positive lenses on the side. Since this negative lens is the only negative lens on the image side from the aperture stop, the burden on aberration correction is large and the manufacturing error becomes severe. By joining this negative lens to the second positive lens, it is possible to make an optical system that is resistant to manufacturing errors, and to suppress the occurrence of higher-order aberrations between the second positive lens and the negative lens. Chromatic aberration can be effectively suppressed. Further, by making the lens closest to the image plane in the second lens group a meniscus lens convex toward the image plane, fluctuations in coma and chromatic aberration during zooming can be reduced.

  Conditional expression (5) defines the power ratio of the first lens and the second lens in the first lens group. In particular, the off-axis light beam on the wide angle side has a large incident angle with respect to the optical axis, and the incident angle on the first surface is also large. One of the functions of the first lens and the second lens is to moderate the angle of the luminous flux with respect to the optical axis at the four surfaces of the first lens and the second lens, but the conditional expression (5) is satisfied. Thus, this function can be more effectively operated. If the lower limit of the conditional expression (5) is less than 1.2, it is difficult to correct coma and astigmatism that occur in the most concave lens on the object side. If it is larger than the upper limit of 2.7, the aberration generated in the second concave lens from the object side becomes too large.

  The fifteenth zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When zooming, the diaphragm moves integrally with the second lens group, the third lens group is composed of one lens, and the second lens group is in order from the object side. It is composed of a positive lens, a positive / negative cemented lens, and a positive lens, and the lens closest to the image plane in the second lens group is a meniscus lens convex to the image plane side, and satisfies the following conditional expression (6): It is a zoom lens.

2 <f ₃ / IH <12 (6)
Here, f ₃ is the focal length of the third lens group, and IH is the image height.

  The operational effects of the fifteenth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact. By constructing the second lens group in order from the object side, a positive lens, a positive and negative cemented lens, and a positive lens, spherical aberration and off-axis coma are generated by two positive lenses arranged near the aperture stop. The positive lens on the image side cooperates with the third lens group to control the off-axis aberration while keeping the exit pupil position away from the image plane, and the negative lens is imaged with the second positive lens from the object side. Chromatic aberration is controlled by placing it between the positive lenses on the side. Since this negative lens is the only negative lens on the image side from the aperture stop, the burden on aberration correction is large and the manufacturing error becomes severe. By joining this negative lens to the second positive lens, it is possible to make an optical system that is resistant to manufacturing errors, and to suppress the occurrence of higher-order aberrations between the second positive lens and the negative lens. Chromatic aberration can be effectively suppressed. Further, by making the lens closest to the image plane in the second lens group a meniscus lens convex toward the image plane, fluctuations in coma and chromatic aberration during zooming can be reduced.

  If the lower limit of 2 of conditional expression (6) is exceeded, the refractive power of the third lens group becomes too strong with respect to the image height, and the difference between the center thickness of the positive lens constituting the third lens group and the peripheral thickness is large. Therefore, the occurrence of aberration of off-axis light flux is increased, which is not preferable. If the upper limit of 12 is exceeded, the refractive power of the third lens group becomes too weak with respect to the image height, and if the total length is kept short, the above-mentioned shading tends to occur at a high image height, which is not preferable.

  The sixteenth zoom lens of the present invention includes, in order from the object side, a first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When zooming, the diaphragm moves integrally with the second lens group, the third lens group is composed of one lens, and the second lens group is in order from the object side. It consists of a positive lens, a positive / negative cemented lens, and a positive lens, and the ratio of the thickness of the positive lens to the negative lens of the cemented lens satisfies the following conditional expression (10) and also satisfies the following conditional expression (4) The zoom lens is characterized by that.

_{1. 9 <d ce1 / d ce2} <12 (10)
_{0.4 <f 3 / f t <} 2.5 ··· (4)
However, d _ce1 the thickness of the convex lens of the cemented lens in the second lens group, d _ce2 the thickness of the concave lens of the cemented lens in the second lens group, f ₃ is the focal length of the third lens group, f _t the telephoto end This is the focal length of the entire system.

  The operational effects of the sixteenth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact. By constructing the second lens group in order from the object side, a positive lens, a positive and negative cemented lens, and a positive lens, spherical aberration and off-axis coma are generated by two positive lenses arranged near the aperture stop. The positive lens on the image side cooperates with the third lens group to control the off-axis aberration while keeping the exit pupil position away from the image plane, and the negative lens is imaged with the second positive lens from the object side. Chromatic aberration is controlled by placing it between the positive lenses on the side. Since this negative lens is the only negative lens on the image side from the aperture stop, the burden on aberration correction is large and the manufacturing error becomes severe. By joining this negative lens to the second positive lens, it is possible to make an optical system that is resistant to manufacturing errors, and to suppress the occurrence of higher-order aberrations between the second positive lens and the negative lens. Chromatic aberration can be effectively suppressed.

  In addition, by defining the ratio of the thickness of the positive lens and the negative lens to be joined as in the conditional expression (10), it is easy to achieve both miniaturization and particularly suppression of astigmatism. If the lower limit of 1.9 to condition (10) is exceeded, it will be difficult to correct astigmatism, which is not preferable. When the upper limit of 12 is exceeded, the cemented lens becomes too thick, which is disadvantageous for miniaturization, and is not preferable.

  By satisfying the conditional expression (4), it is possible to make the imaging performance and the exit pupil position suitable with a small number of constituent elements of the third lens group. If the upper limit is larger than 2.5, it is difficult to keep the exit pupil away while keeping the entire length short. If the lower limit is less than 0.4, the aberration generated in the third lens group becomes too large, and the performance cannot be maintained.

  The seventeenth zoom lens of the present invention includes, in order from the object side, a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When zooming, the diaphragm moves integrally with the second lens group, the third lens group is composed of one lens, and the second lens group is in order from the object side. It consists of a positive lens, a positive / negative cemented lens, and a positive lens, and the ratio of the thickness of the positive lens to the negative lens of the cemented lens satisfies the following conditional expression (10), and from the most object side of the first lens group At least two lenses are negative lenses. A zoom lens and satisfies the equation (4).

_{1. 9 <d ce1 / d ce2} <12 (10)
1.2 <f _1-N / f _2-N <2.7 (5)
However, d _ce1 the thickness of the convex lens of the cemented lens in the second lens group, d _ce2 the thickness of the concave lens of the cemented lens in the second lens group, f _1-N is of the most object side concave in the first lens group focal length, f _2-N is the focal length of the second concave from the object side of the first lens group.

  The operational effects of the seventeenth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact. By constructing the second lens group in order from the object side, a positive lens, a positive and negative cemented lens, and a positive lens, spherical aberration and off-axis coma are generated by two positive lenses arranged near the aperture stop. The positive lens on the image side cooperates with the third lens group to control the off-axis aberration while keeping the exit pupil position away from the image plane, and the negative lens is imaged with the second positive lens from the object side. Chromatic aberration is controlled by placing it between the positive lenses on the side. Since this negative lens is the only negative lens on the image side from the aperture stop, the burden on aberration correction is large and the manufacturing error becomes severe. By joining this negative lens to the second positive lens, it is possible to make an optical system that is resistant to manufacturing errors, and to suppress the occurrence of higher-order aberrations between the second positive lens and the negative lens. Chromatic aberration can be effectively suppressed.

  In addition, by defining the ratio of the thickness of the positive lens and the negative lens to be joined as in the conditional expression (10), it is easy to achieve both miniaturization and particularly suppression of astigmatism. If the lower limit of 1.9 to condition (10) is exceeded, it will be difficult to correct astigmatism, which is not preferable. When the upper limit of 12 is exceeded, the cemented lens becomes too thick, which is disadvantageous for miniaturization, and is not preferable.

  Conditional expression (5) defines the power ratio of the first lens and the second lens in the first lens group. In particular, the off-axis light beam on the wide angle side has a large incident angle with respect to the optical axis, and the incident angle on the first surface is also large. One of the functions of the first lens and the second lens is to moderate the angle of the luminous flux with respect to the optical axis at the four surfaces of the first lens and the second lens, but the conditional expression (5) is satisfied. Thus, this function can be more effectively operated. If the lower limit of the conditional expression (5) is less than 1.2, it is difficult to correct coma and astigmatism that occur in the most concave lens on the object side. If it is larger than the upper limit of 2.7, the aberration generated in the second concave lens from the object side becomes too large.

  The eighteenth zoom lens of the present invention includes, in order from the object side, a first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed and the intervals of the first lens group, the second lens group, and the third lens group are changed. When zooming, the diaphragm moves integrally with the second lens group, the third lens group is composed of one lens, and the second lens group is in order from the object side. It consists of a positive lens, a positive / negative cemented lens, and a positive lens, and the ratio of the thickness of the positive lens to the negative lens of the cemented lens satisfies the following conditional expression (10) and satisfies the following conditional expression (6): The zoom lens is characterized by that.

_{1. 9 <d ce1 / d ce2} <12 (10)
2 <f ₃ / IH <12 (6)
However, d _ce1 the thickness of the convex lens of the cemented lens in the second lens group, d _ce2 the thickness of the concave lens of the cemented lens in the second lens group, f ₃ is the focal length of the third lens group, the IH is image height is there.

  The operational effects of the eighteenth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. At this time, the third lens group can be shortened in length on the optical axis of the third lens group by making the number of constituent elements to be one, which is desirable for making the entire length compact. By constructing the second lens group in order from the object side, a positive lens, a positive and negative cemented lens, and a positive lens, spherical aberration and off-axis coma are generated by two positive lenses arranged near the aperture stop. The positive lens on the image side cooperates with the third lens group to control the off-axis aberration while keeping the exit pupil position away from the image plane, and the negative lens is imaged with the second positive lens from the object side. Chromatic aberration is controlled by placing it between the positive lenses on the side. Since this negative lens is the only negative lens on the image side from the aperture stop, the burden on aberration correction is large and the manufacturing error becomes severe. By joining this negative lens to the second positive lens, it is possible to make an optical system that is resistant to manufacturing errors, and to suppress the occurrence of higher-order aberrations between the second positive lens and the negative lens. Chromatic aberration can be effectively suppressed.

  In addition, by defining the ratio of the thickness of the positive lens and the negative lens to be joined as in the conditional expression (10), it is easy to achieve both miniaturization and particularly suppression of astigmatism. If the lower limit of 1.9 to condition (10) is exceeded, it will be difficult to correct astigmatism, which is not preferable. When the upper limit of 12 is exceeded, the cemented lens becomes too thick, which is disadvantageous for miniaturization, and is not preferable.

  If the lower limit of 2 of conditional expression (6) is exceeded, the refractive power of the third lens group becomes too strong with respect to the image height, and the difference between the center thickness of the positive lens constituting the third lens group and the peripheral thickness is large. Therefore, the occurrence of aberration of off-axis light flux is increased, which is not preferable. If the upper limit of 12 is exceeded, the refractive power of the third lens group becomes too weak with respect to the image height, and if the total length is kept short, the above-mentioned shading tends to occur at a high image height, which is not preferable.

  The nineteenth zoom lens of the present invention includes, in order from the object side, a first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The first lens group and the second lens group move on the optical axis, and the third lens group is fixed to change the intervals of the first lens group, the second lens group, and the third lens group. When changing magnification, the diaphragm moves together with the second lens group, and the first lens group includes, in order from the object side, a negative lens, a negative lens, and a positive lens. The three-lens group is a zoom lens including one lens having an aspheric surface on the object side that satisfies the conditional expression (2).

−1 <(1 / r _a3 −1 / r _m3 ) h ₃ / (n _a3 −n _a3 ′) <0 (2)
However, r _a3 is a paraxial radius of curvature of the aspherical surface III which is disposed in the third lens group, r _m3 is from the intersection of the aspherical III disposed on the optical axis and the third lens group, the aspherical surface III The distance to the point on the optical axis at which the normal at the arbitrary point (3) between the maximum diameter of the on-axis light beam and the effective diameter including the off-axis light beam is closest to the optical axis, _na3 is the aspherical surface III The refractive index on the object side, n _a3 ′ is the refractive index on the image side of the aspheric surface III, and h ₃ is the height of the point (3) from the optical axis.

  The effects of the nineteenth zoom lens of the present invention will be described.

  By moving and changing the magnification of the first lens group having negative power and the second lens group having positive power, a zoom lens having a wide angle of view, particularly at the wide-angle end, can be configured compactly with high performance. . An exit pupil position suitable for an electronic imaging device can be configured by a third lens group having a fixed positive power during zooming and an aperture stop that moves together with the second lens group during zooming. That is, the exit pupil position can be arranged at a position away from the imaging plane in consideration of shading and the like. By making the third lens group one lens, it is possible to reduce the length of the third lens group on the optical axis, which is desirable for making the entire length compact.

  At this time, the third lens group does not greatly affect the deterioration of the aberration with respect to the axial light beam, but off-axis light beam, particularly astigmatism, is likely to occur. Depending on the performance of the image sensor and the like, it is possible to increase the imaging performance by increasing the number of constituent elements of the third lens group, but by arranging an aspheric surface that satisfies the conditional expression (2), It can be composed of a single positive lens. That is, by satisfying the conditional expression (2), the difference between the center thickness of the lens and the thickness of the peripheral portion can be reduced, and a high imaging performance such as an image sensor with a large number of pixels is required. The occurrence of point aberration can be reduced. In particular, by placing an aspheric surface on the object side where the off-axis light beam is inclined with respect to the optical axis and the incident angle on the lens tends to be large, the exit pupil is kept away while keeping the entire length short. This is advantageous for correction of point aberration and coma. If the upper limit of 0 in conditional expression (2) is exceeded, the effect of the aspherical surface will be lost, and astigmatism will not be suppressed. If the lower limit of -1 is exceeded, the substantial exit pupil position for off-axis light will be disadvantageous. This is not preferable because the off-axis light beam is incident from a direction greatly deviated from the vertical direction with respect to the imaging surface.

  As is apparent from the above description, according to the present invention, a zoom lens having a zoom ratio of about 3 times, a wide angle of view on the wide-angle side, and a bright F-number can obtain good imaging performance. The zoom lens can be provided, and a zoom lens with good manufacturability can be provided. Furthermore, it is possible to provide a zoom lens that is small and particularly suitable for a small portable information terminal.

  Examples 1 to 11 of the zoom lens according to the present invention will be described below. Examples 2, 6, and 10 are reference examples.

  1 to 11 are sectional views showing lens arrangements at the wide-angle end of the zoom lenses of Examples 1 to 11, respectively. Numerical data of each example will be described later. 1 to 11, a parallel plate is disposed between the third group G3 and the image plane. These are filters such as an IR cut filter, a low-pass filter, and a cover glass of an image sensor. It is kind. These parallel flat plates are omitted in the numerical data described later.

  Example 1 is a zoom lens having a focal length of 4.386 to 12.642 mm, an F number of 2.36 to 3.99, a half angle of view of 37.9 to 14.4 °, and an image height of 3.32 mm. As shown in FIG. 1, the first lens group G1 includes a negative meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side, and a lens made aspheric by applying a thin resin to the concave surface. And a positive meniscus lens having a convex surface facing the object side. The second group G2 includes a diaphragm disposed on the object side, a biconvex lens, a cemented lens of a biconvex lens and a biconcave lens, and a convex surface on the image surface side. The third group G3 is composed of one biconvex lens. The aspheric surfaces are the resin aspheric surface provided on the second negative meniscus lens of the first group G1, the most object side surface of the second group G2, and the object side surface of the biconvex lens of the third group G3. Used on three sides. During zooming from the wide-angle end to the telephoto end, as indicated by an arrow in the figure, the first lens group G1 moves from the object side to the image plane side, reverses in the middle, and slightly returns to the object side. The second group G2 moves from the image plane side to the object side. The third group G3 is fixed.

  Example 2 is a zoom lens having a focal length of 4.375 to 12.649 mm, an F number of 2.83 to 4.62, a half angle of view of 37.8 to 15.8 °, and an image height of 3.32 mm. As shown in FIG. 1, the first group G1 includes three negative meniscus lenses having a convex surface facing the object side and positive meniscus lenses having a convex surface facing the object side, and the second group G2 is disposed on the object side. The third lens group G3 is composed of one biconvex lens. The aperture stop, the biconvex lens, the cemented lens of the biconvex lens and the biconcave lens, and the biconvex lens. The aspherical surfaces are the three surfaces of the third negative meniscus lens surface of the first group G1, the most object side surface of the second group G2, and the object side surface of the biconvex lens of the third group G3. It is used for. During zooming from the wide-angle end to the telephoto end, as indicated by an arrow in the figure, the first lens group G1 moves from the object side to the image plane side, reverses in the middle, and slightly returns to the object side. The second group G2 moves from the image plane side to the object side. The third group G3 is fixed.

  Example 3 is a zoom lens having a focal length of 4.374 to 12.649 mm, an F number of 2.31 to 4.00, a half angle of view of 37.9 to 15.8 °, and an image height of 3.32 mm. As shown in FIG. 1, the first group G1 includes two negative meniscus lenses having a convex surface facing the object side and positive meniscus lenses having a convex surface facing the object side, and the second group G2 is disposed on the object side. The aperture stop, the biconvex lens, the cemented lens of the biconvex lens and the biconcave lens, and a positive meniscus lens having a convex surface facing the object side, and the third group G3 includes one biconvex lens. The aspherical surfaces are three surfaces: the image side surface of the second negative meniscus lens of the first group G1, the most object side surface of the second group G2, and the object side surface of the biconvex lens of the third group G3. It is used for. During zooming from the wide-angle end to the telephoto end, as indicated by an arrow in the figure, the first lens group G1 moves from the object side to the image plane side, reverses in the middle, and slightly returns to the object side. The second group G2 moves from the image plane side to the object side. The third group G3 is fixed.

  Example 4 is a zoom lens having a focal length of 4.374 to 12.648 mm, an F number of 2.31 to 4.00, a half angle of view of 38.0 to 15.6 °, and an image height of 3.32 mm. As shown in FIG. 1, the first group G1 includes two negative meniscus lenses having a convex surface facing the object side and positive meniscus lenses having a convex surface facing the object side, and the second group G2 is disposed on the object side. The third lens group G3 is composed of one biconvex lens. The aperture stop, the biconvex lens, the cemented lens of the biconvex lens and the biconcave lens, and the biconvex lens. The aspherical surfaces are three surfaces: the image side surface of the first negative meniscus lens of the first group G1, the most object side surface of the second group G2, and the object side surface of the biconvex lens of the third group G3. It is used for. During zooming from the wide-angle end to the telephoto end, as indicated by an arrow in the figure, the first lens group G1 moves from the object side to the image plane side, reverses in the middle, and slightly returns to the object side. The second group G2 moves from the image plane side to the object side. The third group G3 is fixed.

  Example 5 is a zoom lens having a focal length of 4.387 to 12.643 mm, an F number of 2.42 to 4.09, a half angle of view of 37.9 to 14.9 °, and an image height of 3.32 mm. As shown in the figure, the first lens group G1 is composed of a negative meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side, and a lens made aspheric by applying a thin resin to the concave surface. And a positive meniscus lens having a convex surface facing the object side. The second group G2 includes a diaphragm disposed on the object side, a biconvex lens, a cemented lens of a biconvex lens and a biconcave lens, and a convex surface on the image side. The third group G3 is composed of one biconvex lens. The aspheric surfaces are used for the two surfaces of the resin aspheric surface provided on the second negative meniscus lens of the first group G1 and the most object side surface of the second group G2. During zooming from the wide-angle end to the telephoto end, as indicated by an arrow in the figure, the first lens group G1 moves from the object side to the image plane side, reverses in the middle, and slightly returns to the object side. The second group G2 moves from the image plane side to the object side. The third group G3 is fixed.

  Example 6 is a zoom lens having a focal length of 4.371 to 12.622 mm, an F number of 2.32 to 4.00, a half angle of view of 38.1 to 13.9 °, and an image height of 3.32 mm. As shown in FIG. 1, the first group G1 includes two negative meniscus lenses having a convex surface facing the object side, a negative meniscus lens having a convex surface facing the image surface side, and a positive meniscus lens having a convex surface facing the image surface side. The second group G2 includes a stop disposed on the object side, a biconvex lens, a cemented lens of a biconvex lens and a biconcave lens, and a positive meniscus lens having a convex surface facing the object side. G3 is composed of one biconvex lens. The aspheric surfaces are used for the three surfaces of the second group G2, the most object side surface, the cemented lens object side surface, and the object side surface of the biconvex lens of the third group G3. When zooming from the wide-angle end to the telephoto end, as indicated by an arrow in the figure, the first group G1 moves from the object side to the image plane side. The second group G2 moves from the image plane side to the object side. The third group G3 is fixed.

  Example 7 is a zoom lens having a focal length of 2.973 to 8.568 mm, an F number of 2.42 to 4.09, a half angle of view of 37.9 to 14.4 °, and an image height of 2.25 mm. As shown in the figure, the first lens group G1 is composed of a negative meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side, and a lens made aspheric by applying a thin resin to the concave surface. And a positive meniscus lens having a convex surface facing the object side. The second group G2 includes a diaphragm disposed on the object side, a biconvex lens, a cemented lens of a biconvex lens and a biconcave lens, and a convex surface on the image side. The third group G3 is composed of one biconvex lens. The aspheric surfaces are used for the two surfaces of the resin aspheric surface provided on the second negative meniscus lens of the first group G1 and the most object side surface of the second group G2. During zooming from the wide-angle end to the telephoto end, as indicated by an arrow in the figure, the first lens group G1 moves from the object side to the image plane side, reverses in the middle, and slightly returns to the object side. The second group G2 moves from the image plane side to the object side. The third group G3 is fixed.

  Example 8 is a zoom lens having a focal length of 3.293 to 9.524 mm, an F number of 2.31 to 4.00, a half angle of view of 38.0 to 15.6 °, and an image height of 2.5 mm. As shown in FIG. 1, the first group G1 is composed of a negative meniscus lens having a convex surface facing the object side, a biconcave lens, and a positive meniscus lens having a convex surface facing the object side. The aperture stop, the biconvex lens, the cemented lens of the biconvex lens and the biconcave lens, and the biconvex lens are included. The third group G3 includes one biconvex lens. The aspherical surfaces are used for three surfaces: the image side surface of the negative meniscus lens of the first group G1, the most object side surface of the second group G2, and the object side surface of the biconvex lens of the third group G3. ing. During zooming from the wide-angle end to the telephoto end, as indicated by an arrow in the figure, the first lens group G1 moves from the object side to the image plane side, reverses in the middle, and slightly returns to the object side. The second group G2 moves from the image plane side to the object side. The third group G3 is fixed.

  Example 9 is a zoom lens having a focal length of 2.378 to 6.854 mm, an F number of 2.36 to 3.99, a half angle of view of 37.9 to 14.4 °, and an image height of 1.8 mm. As shown in the figure, the first lens group G1 is composed of a negative meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side, and a lens made aspheric by applying a thin resin to the concave surface. And a positive meniscus lens having a convex surface facing the object side. The second group G2 includes a diaphragm disposed on the object side, a biconvex lens, a cemented lens of a biconvex lens and a biconcave lens, and a convex surface on the image side. The third group G3 is composed of one biconvex lens. The aspheric surfaces are the resin aspheric surface provided on the second negative meniscus lens of the first group G1, the most object side surface of the second group G2, and the object side surface of the biconvex lens of the third group G3. Used on three sides. During zooming from the wide-angle end to the telephoto end, as indicated by an arrow in the figure, the first lens group G1 moves from the object side to the image plane side, reverses in the middle, and slightly returns to the object side. The second group G2 moves from the image plane side to the object side. The third group G3 is fixed.

  Example 10 is a zoom lens having a focal length of 1.975 to 5.703 mm, an F number of 2.32 to 4.00, a half angle of view of 38.1 to 13.9 °, and an image height of 1.5 mm. As shown in FIG. 1, the first group G1 includes two negative meniscus lenses having a convex surface facing the object side, a negative meniscus lens having a convex surface facing the image surface side, and a positive meniscus lens having a convex surface facing the image surface side. The second group G2 includes a stop disposed on the object side, a biconvex lens, a cemented lens of a biconvex lens and a biconcave lens, and a positive meniscus lens having a convex surface facing the object side. G3 is composed of one biconvex lens. The aspheric surfaces are used for the three surfaces of the second group G2, the most object side surface, the cemented lens object side surface, and the object side surface of the biconvex lens of the third group G3. When zooming from the wide-angle end to the telephoto end, as indicated by an arrow in the figure, the first group G1 moves from the object side to the image plane side. The second group G2 moves from the image plane side to the object side. The third group G3 is fixed.

  Example 11 is a zoom lens having a focal length of 2.635 to 7.620 mm, an F number of 2.31 to 4.00, a half angle of view of 37.9 to 15.8 °, and an image height of 2.0 mm. As shown in FIG. 1, the first group G1 includes two negative meniscus lenses having a convex surface facing the object side and positive meniscus lenses having a convex surface facing the object side, and the second group G2 is disposed on the object side. The aperture stop, the biconvex lens, the cemented lens of the biconvex lens and the biconcave lens, and a positive meniscus lens having a convex surface facing the object side, and the third group G3 includes one biconvex lens. The aspherical surfaces are three surfaces: the image side surface of the second negative meniscus lens of the first group G1, the most object side surface of the second group G2, and the object side surface of the biconvex lens of the third group G3. It is used for. During zooming from the wide-angle end to the telephoto end, as indicated by an arrow in the figure, the first lens group G1 moves from the object side to the image plane side, reverses in the middle, and slightly returns to the object side. The second group G2 moves from the image plane side to the object side. The third group G3 is fixed.

The numerical data of each of the above embodiments are shown below. Symbols are the above, f is the total focal length, _FNO is the F number, ω is the half field angle, r ₁ , r ₂ . The radius of curvature, d ₁ , d ₂ ... Is the distance between the lens surfaces, n _d1 , n _d2 ... Is the refractive index of the d-line of each lens, and ν _d1 , ν _d2 . . The aspherical shape is expressed by the following expression, where x is an optical axis with the traveling direction of light as positive and y is in a direction perpendicular to the optical axis.

x = (y ² / r) / [1+ {1- (K + 1) (y / r) ² } ^1/2 ]
_{^{+ A 4 y 4 + A 6}} y 6 + A 8 y 8 + A 10 y 10
Here, r is a paraxial radius of curvature, K is a conical coefficient, and A ₄ , A ₆ , A ₈ , and A ₁₀ are fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, respectively.

Example 1
f = 4.386 to 7.451 to 12.642
F _NO = 2.36 to 2.96 to 3.99
ω = 37.9 ° to 23.7 ° to 14.4 °
r ₁ = 30.608 d ₁ = 1.10 n _d1 = 1.69680 ν _d1 = 55.53
r ₂ = 9.922 d ₂ = 2.42
r ₃ = 27.009 d ₃ = 0.95 n _d2 = 1.78590 ν _d2 = 44.20
r ₄ = 8.504 d ₄ = 0.10 n _d3 = 1.52555 ν _d3 = 52.45
r ₅ = 6.982 (aspherical surface) d ₅ = 2.73
r ₆ = 12.311 d ₆ = 2.23 n _d4 = 1.80518 ν _d4 = 25.42
r ₇ = 32.087 d ₇ = (variable)
r ₈ = ∞ (aperture) d ₈ = 0.94
r ₉ = 30.723 (aspherical surface) d ₉ = 1.60 n _d5 = 1.60311 ν _d5 = 60.64
r ₁₀ = -12.949 d ₁₀ = 0.50
r ₁₁ = 5.242 d ₁₁ = 3.55 n _d6 = 1.61272 ν _d6 = 58.72
r ₁₂ = -89.064 d ₁₂ = 0.50 n _d7 = 1.74077 ν _d7 = 27.79
r ₁₃ = 3.847 d ₁₃ = 2.19
_{r 14 = -20.881 d 14 = 1.37} n d8 = 1.51633 ν d8 = 64.14
r ₁₅ = -9.365 d ₁₅ = (variable)
r ₁₆ = 39.137 (aspherical surface) d ₁₆ = 2.46 n _d9 = 1.56384 ν _d9 = 60.67
r ₁₇ = -9.532 d ₁₇ = 4.20
r ₁₈ = ∞ (image plane)
Zoom interval ┌──┬────┬────┬────┐
│f │ 4.386 │ 7.451 │ 12.642 │
├──┼────┼┼────┼────┤
│d ₇ │ 17.15 │ 6.98 │ 1.00 │
├──┼────┼┼────┼────┤
│d ₁₅ │ 1.00 │ 5.01 │ 11.77 │
└──┴────┴┴────┴────┘
Aspheric coefficient Fifth surface K = 0.000
A ₄ = -4.37407 × 10 ^-4
A ₆ = 2.95376 × 10 ^-10
A ₈ = -1.05245 × 10 ^-7
A ₁₀ = -2.15246 × ₁₀ ^-9
Surface 9 K = 0.000
A ₄ = -2.05174 × 10 ^-4
A ₆ = -6.60605 × 10 ^-6
A ₈ = 8.45958 × 10 ^-7
A ₁₀ = -3.81345 × 10 ^-8
16th surface K = 0.000
A ₄ = -5.57767 × 10 ^-4
A ₆ = 1.64691 × 10 ^-5
A ₈ = -8.27513 × 10 ^-7
A ₁₀ = 1.69001 × 10 ^-8 .

Example 2
f = 4.375 to 7.411 to 12.649
F _NO = 2.83 to 3.48 to 4.62
ω = 37.8 ° to 24.1 ° to 15.8 °
r ₁ = 15.773 d ₁ = 1.10 n _d1 = 1.69680 ν _d1 = 55.53
r ₂ = 9.476 d ₂ = 1.53
r ₃ = 14.021 d ₃ = 1.00 n _d2 = 1.69680 ν _d2 = 55.53
r ₄ = 8.058 d ₄ = 2.59
r ₅ = 40.949 d ₅ = 0.80 n _d3 = 1.88300 ν _d3 = 40.76
r ₆ = 7.484 (aspherical surface) d ₆ = 2.33
r ₇ = 14.074 d ₇ = 2.21 n _d4 = 1.80518 ν _d4 = 25.42
r ₈ = 315.362 d ₈ = (variable)
r ₉ = ∞ (aperture) d ₉ = 0.87
r ₁₀ = 8.943 (aspherical surface) d ₁₀ = 2.80 n _d5 = 1.60311 ν _d5 = 60.64
r ₁₁ = -19.486 d ₁₁ = 1.74
r ₁₂ = 11.249 d ₁₂ = 3.34 n _d6 = 1.61272 ν _d6 = 58.72
r ₁₃ = -8.479 d ₁₃ = 0.50 n _d7 = 1.74077 ν _d7 = 27.79
r ₁₄ = 5.482 d ₁₄ = 3.17
r ₁₅ = 15.126 d ₁₅ = 2.29 n _d8 = 1.60342 ν _d8 = 38.03
r ₁₆ = -48.736 d ₁₆ = (variable)
r ₁₇ = 12.445 (aspherical surface) d ₁₇ = 1.39 n _d9 = 1.56384 ν _d9 = 60.67
r ₁₈ = -250.472 d ₁₈ = 4.21
r ₁₉ = ∞ (image plane)
Zoom interval ┌──┬────┬────┬────┐
│f │ 4.375 │ 7.411 │ 12.649 │
├──┼────┼┼────┼────┤
│d ₈ │ 16.57 │ 6.83 │ 1.00 │
├──┼────┼┼────┼────┤
│d ₁₆ │ 0.50 │ 5.03 │ 12.82 │
└──┴────┴┴────┴────┘
Aspheric coefficient 6th surface K = 0.000
A ₄ = -3.68865 × 10 ^-4
A ₆ = -1.90729 × 10 ^-6
A ₈ = -9.53501 × 10 ^-8
A ₁₀ = 8.24639 × 10 ^-12
10th surface K = 0.000
A ₄ = -2.77414 × 10 ^-4
A ₆ = 2.77354 × 10 ^-6
A ₈ = -4.45517 × 10 ^-7
A ₁₀ = 1.14044 × 10 ^-8
Surface 17 K = 0.000
A ₄ = -2.92081 × 10 ^-4
A ₆ = 1.48703 × 10 ^-5
A ₈ = -6.56437 × 10 ^-7
A ₁₀ = 1.02200 × 10 ⁻⁸ .

Example 3
f = 4.374 to 7.448 to 12.649
F _NO = 2.31 to 2.93 to 4.00
ω = 37.9 ° to 24.0 ° to 15.8 °
r ₁ = 20.947 d ₁ = 0.95 n _d1 = 1.69680 ν _d1 = 55.53
r ₂ = 6.794 d ₂ = 3.43
r ₃ = 25.746 d ₃ = 0.70 n _d2 = 1.78590 ν _d2 = 44.20
r ₄ = 6.745 (aspherical surface) d ₄ = 2.48
r ₅ = 13.847 d ₅ = 2.10 n _d3 = 1.80518 ν _d3 = 25.42
r ₆ = 102.749 d ₆ = (variable)
r ₇ = ∞ (aperture) d ₇ = 0.70
r ₈ = 8.691 (aspherical surface) d ₈ = 3.92 n _d4 = 1.60311 ν _d4 = 60.64
r ₉ = -18.462 d ₉ = 0.50
r ₁₀ = 9.505 d ₁₀ = 3.45 n _d5 = 1.61272 ν _d5 = 58.72
r ₁₁ = -10.051 d ₁₁ = 0.50 n _d6 = 1.74077 ν _d6 = 27.79
r ₁₂ = 4.905 d ₁₂ = 3.42
_{r 13 = 15.706 d 13 = 1.01} n d7 = 1.60342 ν d7 = 38.03
r ₁₄ = 17250.422 d ₁₄ = (variable)
r ₁₅ = 11.303 (aspherical surface) d ₁₅ = 1.78 n _d8 = 1.56384 ν _d8 = 60.67
r ₁₆ = -48.249 d ₁₆ = 3.94
r ₁₇ = ∞ (image plane)
Zoom interval ┌──┬────┬────┬────┐
│f │ 4.374 │ 7.448 │ 12.649 │
├──┼────┼┼────┼────┤
│d ₆ │ 15.02 │ 6.19 │ 1.00 │
├──┼────┼┼────┼────┤
│d ₁₄ │ 1.00 │ 5.80 │ 13.87 │
└──┴────┴┴────┴────┘
Aspheric coefficient 4th surface K = 0.000
A ₄ = -5.75781 × 10 ^-4
A ₆ = -2.01153 × 10 ^-6
A ₈ = -2.60007 × 10 ^-7
A ₁₀ = -3.72946 × ₁₀ ^-10
8th surface K = 0.000
A ₄ = -2.80524 × 10 ^-4
A ₆ = -1.61468 × 10 ^-6
A ₈ = -1.94898 × 10 ^-8
A ₁₀ = -1.27601 × 10 ^-10
15th face K = 0.000
A ₄ = -2.70433 × 10 ^-4
A ₆ = 1.36913 × 10 ^-5
A ₈ = -6.86548 × 10 ^-7
A ₁₀ = 1.27612 × 10 ⁻⁸ .

Example 4
f = 4.374 to 7.448 to 12.648
F _NO = 2.31 to 2.93 to 4.00
ω = 38.0 ° to 23.8 ° to 15.6 °
r ₁ = 73.199 d ₁ = 1.10 n _d1 = 1.69680 ν _d1 = 55.53
r ₂ = 13.721 (aspherical surface) d ₂ = 3.98
r ₃ = -1281.699 d ₃ = 0.95 n _d2 = 1.81600 ν _d2 = 46.62
r ₄ = 8.202 d ₄ = 3.12
_{r 5 = 14.786 d 5 = 2.05} n d3 = 1.80518 ν d3 = 25.42
r ₆ = 88.390 d ₆ = (variable)
r ₇ = ∞ (aperture) d ₇ = 0.42
r ₈ = 23.686 (aspherical surface) d ₈ = 1.66 n _d4 = 1.60311 ν _d4 = 60.64
r ₉ = -16.220 d ₉ = 0.50
r ₁₀ = 6.386 d ₁₀ = 4.62 n _d5 = 1.61272 ν _d5 = 58.72
r ₁₁ = -13.321 d ₁₁ = 0.50 n _d6 = 1.72825 ν _d6 = 28.46
r ₁₂ = 4.469 d ₁₂ = 2.75
r ₁₃ = 46.980 d ₁₃ = 1.64 n _d7 = 1.51633 ν _d7 = 64.14
r ₁₄ = -18.186 d ₁₄ = (variable)
r ₁₅ = 19.128 _{(aspherical) d 15 = 2.30 n d8 =} 1.56384 ν d8 = 60.67
r ₁₆ = -14.925 d ₁₆ = 4.19
r ₁₇ = ∞ (image plane)
Zoom interval ┌──┬────┬────┬────┐
│f │ 4.374 │ 7.448 │ 12.648 │
├──┼────┼┼────┼────┤
│d ₆ │ 16.12 │ 6.58 │ 1.00 │
├──┼────┼┼────┼────┤
│d ₁₄ │ 1.00 │ 5.73 │ 13.69 │
└──┴────┴┴────┴────┘
Aspheric coefficient 2nd surface K = 0.000
A ₄ = -1.83153 × 10 ^-4
A ₆ = -3.40705 × 10 ^-7
A ₈ = 1.25210 × 10 ^-13
A ₁₀ = -9.97522 × 10 ^-12
8th surface K = 0.000
A ₄ = -1.00639 × 10 ^-4
A ₆ = -1.18430 × 10 ^-6
A ₈ = 2.11991 × 10 ^-7
A ₁₀ = -9.90194 × 10 ^-9
15th face K = 0.000
A ₄ = -4.01115 × 10 ^-4
A ₆ = 1.35678 × 10 ^-5
A ₈ = -6.19449 × 10 ^-7
A ₁₀ = 1.00098 × 10 ⁻⁸ .

Example 5
f = 4.387 to 7.451 to 12.643
F _NO = 2.42 to 3.04 to 4.09
ω = 37.9 ° to 24.2 ° to 14.9 °
r ₁ = 20.677 d ₁ = 1.10 n _d1 = 1.69680 ν _d1 = 55.53
r ₂ = 8.565 d ₂ = 3.49
r ₃ = 37.351 d ₃ = 0.95 n _d2 = 1.81600 ν _d2 = 46.62
r ₄ = 9.087 d ₄ = 0.10 n _d3 = 1.52555 ν _d3 = 52.45
r ₅ = 7.102 (aspherical surface) d ₅ = 3.09
r ₆ = 15.013 d ₆ = 2.20 n _d4 = 1.80518 ν _d4 = 25.42
r ₇ = 78.101 d ₇ = (variable)
r ₈ = ∞ (aperture) d ₈ = 0.96
r ₉ = 192.084 (aspherical surface) d ₉ = 1.47 n _d5 = 1.60311 ν _d5 = 60.64
r ₁₀ = -12.882 d ₁₀ = 0.50
r ₁₁ = 6.097 d ₁₁ = 5.24 n _d6 = 1.61272 ν _d6 = 58.72
r ₁₂ = -9.764 d ₁₂ = 0.50 n _d7 = 1.74077 ν _d7 = 27.79
r ₁₃ = 4.498 d ₁₃ = 2.15
r ₁₄ = -58.594 d ₁₄ = 1.47 n _d8 = 1.60342 ν _d8 = 38.03
r ₁₅ = -11.441 d ₁₅ = (variable)
r ₁₆ = 14.316 d ₁₆ = 2.75 n _d9 = 1.56384 ν _d9 = 60.67
r ₁₇ = -18.860 d ₁₇ = 4.20
r ₁₈ = ∞ (image plane)
Zoom interval ┌──┬────┬────┬────┐
│f │ 4.387 │ 7.451 │ 12.643 │
├──┼────┼┼────┼────┤
│d ₇ │ 17.82 │ 7.23 │ 1.00 │
├──┼────┼┼────┼────┤
│d ₁₅ │ 1.00 │ 5.63 │ 13.44 │
└──┴────┴┴────┴────┘
Aspheric coefficient Fifth surface K = 0.000
A ₄ = -5.06617 × 10 ^-4
A ₆ = 2.08894 × 10 ^-10
A ₈ = -1.83217 × 10 ^-7
A ₁₀ = -2.12210 × 10 ^-10
Surface 9 K = 0.000
A ₄ = -1.20398 × 10 ^-4
A ₆ = -4.22111 × 10 ^-6
A ₈ = 5.21447 × 10 ^-7
A ₁₀ = -1.71674 × 10 ⁻⁸ .

Example 6
f = 4.371 to 4.898 to 12.622
F _NO = 2.32 to 2.42 to 4.00
ω = 38.1 ° to 24.8 ° to 13.9 °
r ₁ = 26.445 d ₁ = 1.10 n _d1 = 1.69680 ν _d1 = 55.53
r ₂ = 11.792 d ₂ = 2.81
r ₃ = 68.200 d ₃ = 1.00 n _d2 = 1.69680 ν _d2 = 55.53
r ₄ = 14.028 d ₄ = 3.16
r ₅ = -23.225 d ₅ = 0.90 n _d3 = 1.88300 ν _d3 = 40.76
r ₆ = -4325.882 d ₆ = 1.34
r ₇ = -20.775 d ₇ = 1.72 n _d4 = 1.80518 ν _d4 = 25.42
r ₈ = -11.656 d ₈ = (variable)
r ₉ = ∞ (aperture) d ₉ = 1.70
r ₁₀ = 6.001 (aspherical surface) d ₁₀ = 2.03 n _d5 = 1.60311 ν _d5 = 60.64
r ₁₁ = -18.104 d ₁₁ = 2.19
r ₁₂ = 132.728 (aspherical surface) d ₁₂ = 1.01 n _d6 = 1.61272 ν _d6 = 58.72
r ₁₃ = -11.240 d ₁₃ = 0.50 n _d7 = 1.74077 ν _d7 = 27.79
r ₁₄ = 4.411 d ₁₄ = 1.28
r ₁₅ = 7.374 d ₁₅ = 1.11 n _d8 = 1.60342 ν _d8 = 38.03
r ₁₆ = 53.534 d ₁₆ = (variable)
r ₁₇ = 88.907 (aspherical surface) d ₁₇ = 4.56 n _d9 = 1.56384 ν _d9 = 60.67
r ₁₈ = -8.781 d ₁₈ = 4.35
r ₁₉ = ∞ (image plane)
Zoom interval ┌──┬────┬────┬────┐
│f │ 4.371 │ 4.898 │ 12.622 │
├──┼────┼┼────┼────┤
│d ₈ │ 18.99 │ 15.85 │ 1.00 │
├──┼────┼┼────┼────┤
│d ₁₆ │ 0.50 │ 1.25 │ 11.73 │
└──┴────┴┴────┴────┘
Aspheric coefficient 10th surface K = 0.000
A ₄ = -6.37232 × 10 ^-4
A ₆ = -4.39285 × 10 ^-6
A ₈ = -1.16573 × 10 ^-6
A ₁₀ = 3.24269 × 10 ^-8
Surface 12 K = 0.000
A ₄ = 3.49239 × 10 ^-4
A ₆ = -1.39146 × 10 ^-5
A ₈ = 3.75806 × 10 ^-6
A ₁₀ = 5.39048 × 10 ^-9
Surface 17 K = 0.000
A ₄ = -1.22514 × 10 ^-3
A ₆ = -1.04830 × 10 ^-5
A ₈ = -6.78577 × 10 ^-7
A ₁₀ = 4.26779 × 10 ^-8 .

Example 7
f = 2.973-5.050-8.568
F _NO = 2.42 to 3.04 to 4.09
ω = 37.9 ° to 23.7 ° to 14.4 °
r ₁ = 14.013 d ₁ = 0.75 n _d1 = 1.69680 ν _d1 = 55.53
r ₂ = 5.805 d ₂ = 2.36
r ₃ = 25.313 d ₃ = 0.64 n _d2 = 1.81600 ν _d2 = 46.62
r ₄ = 6.158 d ₄ = 0.07 n _d3 = 1.52555 ν _d3 = 52.45
r ₅ = 4.813 (aspherical surface) d ₅ = 2.10
r ₆ = 10.175 d ₆ = 1.49 n _d4 = 1.80518 ν _d4 = 25.42
r ₇ = 52.930 d ₇ = (variable)
r ₈ = ∞ (aperture) d ₈ = 0.65
r ₉ = 130.178 (aspherical surface) d ₉ = 1.00 n _d5 = 1.60311 ν _d5 = 60.64
r ₁₀ = -8.730 d ₁₀ = 0.34
r ₁₁ = 4.132 d ₁₁ = 3.55 n _d6 = 1.61272 ν _d6 = 58.72
r ₁₂ = -6.617 d ₁₂ = 0.34 n _d7 = 1.74077 ν _d7 = 27.79
r ₁₃ = 3.048 d ₁₃ = 1.46
r ₁₄ = -39.710 d ₁₄ = 0.99 n _d8 = 1.60342 ν _d8 = 38.03
r ₁₅ = -7.754 d ₁₅ = (variable)
r ₁₆ = 9.702 d ₁₆ = 1.86 n _d9 = 1.56384 ν _d9 = 60.67
r ₁₇ = -12.781 d ₁₇ = 2.85
r ₁₈ = ∞ (image plane)
Zoom interval ┌──┬────┬────┬────┐
│f │ 2.973 │ 5.050 │ 8.568 │
├──┼────┼┼────┼────┤
│d ₇ │ 12.07 │ 4.90 │ 0.68 │
├──┼────┼┼────┼────┤
│d ₁₅ │ 0.68 │ 3.82 │ 9.11 │
└──┴────┴┴────┴────┘
Aspheric coefficient Fifth surface K = 0.000
A ₄ = -1.62760 × 10 ^-3
A ₆ = 1.46118 × 10 ^-9
A ₈ = -2.79032 × 10 ^-6
A ₁₀ = -7.03666 × 10 ^-9
Surface 9 K = 0.000
A ₄ = -3.86799 × 10 ^-4
A ₆ = -2.95260 × 10 ^-5
A ₈ = 7.94144 × 10 ^-6
A ₁₀ = -5.69253 × 10 ^-7 .

Example 8
f = 3.293 to 5.609 to 9.524
F _NO = 2.31 to 2.93 to 4.00
ω = 38.0 ° to 23.8 ° to 15.6 °
r ₁ = 55.120 d ₁ = 0.83 n _d1 = 1.69680 ν _d1 = 55.53
r ₂ = 10.332 (aspherical surface) d ₂ = 3.00
r ₃ = -965.135 d ₃ = 0.72 n _d2 = 1.81600 ν _d2 = 46.62
r ₄ = 6.176 d ₄ = 2.35
r ₅ = 11.134 d ₅ = 1.54 n _d3 = 1.80518 ν _d3 = 25.42
r ₆ = 66.559 d ₆ = (variable)
r ₇ = ∞ (aperture) d ₇ = 0.31
r ₈ = 17.836 (aspherical surface) d ₈ = 1.25 n _d4 = 1.60311 ν _d4 = 60.64
r ₉ = -12.214 d ₉ = 0.38
_{r 10 = 4.809 d 10 = 3.48} n d5 = 1.61272 ν d5 = 58.72
r ₁₁ = -10.031 d ₁₁ = 0.38 n _d6 = 1.72825 ν _d6 = 28.46
r ₁₂ = 3.365 d ₁₂ = 2.07
r ₁₃ = 35.376 d ₁₃ = 1.24 n _d7 = 1.51633 ν _d7 = 64.14
r ₁₄ = -13.694 d ₁₄ = (variable)
r ₁₅ = 14.404 (aspherical surface) d ₁₅ = 1.73 n _d8 = 1.56384 ν _d8 = 60.67
r ₁₆ = -11.239 d ₁₆ = 3.16
r ₁₇ = ∞ (image plane)
Zoom interval ┌──┬────┬────┬────┐
│f │ 3.293 │ 5.609 │ 9.524 │
├──┼────┼┼────┼────┤
│d ₆ │ 12.14 │ 4.96 │ 0.75 │
├──┼────┼┼────┼────┤
│d ₁₄ │ 0.75 │ 4.32 │ 10.31 │
└──┴────┴┴────┴────┘
Aspheric coefficient 2nd surface K = 0.000
A ₄ = -4.28951 × 10 ^-4
A ₆ = -1.40724 × 10 ^-6
A ₈ = 9.12064 × 10 ^-13
A ₁₀ = -1.28146 × 10 ^-10
8th surface K = 0.000
A ₄ = -2.35699 × 10 ^-4
A ₆ = -4.89159 × 10 ^-6
A ₈ = 1.54420 × 10 ^-6
A ₁₀ = -1.27205 × 10 ^-7
15th face K = 0.000
A ₄ = -9.39428 × 10 ^-4
A ₆ = 5.60401 × 10 ^-5
A ₈ = -4.51224 × 10 ^-6
A ₁₀ = 1.28590 × 10 ^-7 .

Example 9
f = 2.378 to 4.040 to 6.854
F _NO = 2.36 to 2.96 to 3.99
ω = 37.9 ° to 23.7 ° to 14.4 °
r ₁ = 16.595 d ₁ = 0.60 n _d1 = 1.69680 ν _d1 = 55.53
r ₂ = 5.379 d ₂ = 1.31
r ₃ = 14.644 d ₃ = 0.52 n _d2 = 1.78590 ν _d2 = 44.20
r ₄ = 4.611 d ₄ = 0.05 n _d3 = 1.52555 ν _d3 = 52.45
r ₅ = 3.785 (aspherical surface) d ₅ = 1.48
r ₆ = 6.675 d ₆ = 1.21 n _d4 = 1.80518 ν _d4 = 25.42
r ₇ = 17.397 d ₇ = (variable)
r ₈ = ∞ (aperture) d ₈ = 0.51
r ₉ = 16.657 (aspherical surface) d ₉ = 0.87 n _d5 = 1.60311 ν _d5 = 60.64
r ₁₀ = -7.020 d ₁₀ = 0.27
r ₁₁ = 2.842 d ₁₁ = 1.93 n _d6 = 1.61272 ν _d6 = 58.72
_{r 12 = -48.288 d 12 = 0.27} n d7 = 1.74077 ν d7 = 27.79
r ₁₃ = 2.086 d ₁₃ = 1.19
r ₁₄ = -11.321 d ₁₄ = 0.74 n _d8 = 1.51633 ν _d8 = 64.14
r ₁₅ = -5.077 d ₁₅ = (variable)
r ₁₆ = 21.219 (aspherical surface) d ₁₆ = 1.34 n _d9 = 1.56384 ν _d9 = 60.67
r ₁₇ = -5.168 d ₁₇ = 2.28
r ₁₈ = ∞ (image plane)
Zoom interval ┌──┬────┬────┬────┐
│f │ 2.378 │ 4.040 │ 6.854 │
├──┼────┼┼────┼────┤
│d ₇ │ 9.30 │ 3.79 │ 0.54 │
├──┼────┼┼────┼────┤
│d ₁₅ │ 0.54 │ 2.72 │ 6.38 │
└──┴────┴┴────┴────┘
Aspheric coefficient Fifth surface K = 0.000
A ₄ = -2.74462 × 10 ^-3
A ₆ = 6.30526 × 10 ^-9
A ₈ = -7.64294 × 10 ^-6
A ₁₀ = -5.31771 × 10 ^-7
Surface 9 K = 0.000
A ₄ = -1.28741 × 10 ^-3
A ₆ = -1.41016 × 10 ^-4
A ₈ = 6.14338 × 10 ^-5
A ₁₀ = -9.42124 × 10 ^-6
16th surface K = 0.000
A ₄ = -3.49985 × 10 ^-3
A ₆ = 3.51560 × 10 ^-4
A ₈ = -6.00944 × 10 ^-5
A ₁₀ = 4.17522 × 10 ⁻⁶ .

Example 10
f = 1.975 to 2.213 to 5.703
F _NO = 2.32 to 2.42 to 4.00
ω = 38.1 ° to 24.8 ° to 13.9 °
r ₁ = 11.948 d ₁ = 0.50 n _d1 = 1.69680 ν _d1 = 55.53
r ₂ = 5.328 d ₂ = 1.27
r ₃ = 30.813 d ₃ = 0.45 n _d2 = 1.69680 ν _d2 = 55.53
r ₄ = 6.338 d ₄ = 1.43
r ₅ = -10.493 d ₅ = 0.41 n _d3 = 1.88300 ν _d3 = 40.76
r ₆ = -1954.465 d ₆ = 0.60
r ₇ = -9.386 d ₇ = 0.78 n _d4 = 1.80518 ν _d4 = 25.42
r ₈ = -5.266 d ₈ = (variable)
r ₉ = ∞ (aperture) d ₉ = 0.77
r ₁₀ = 2.711 (aspherical surface) d ₁₀ = 0.92 n _d5 = 1.60311 ν _d5 = 60.64
r ₁₁ = -8.179 d ₁₁ = 0.99
r ₁₂ = 59.968 _{(aspherical) d 12 = 0.46 n d6 =} 1.61272 ν d6 = 58.72
r ₁₃ = -5.078 d ₁₃ = 0.23 n _d7 = 1.74077 ν _d7 = 27.79
r ₁₄ = 1.993 d ₁₄ = 0.58
r ₁₅ = 3.332 d ₁₅ = 0.50 n _d8 = 1.60342 ν _d8 = 38.03
r ₁₆ = 24.187 d ₁₆ = (variable)
r ₁₇ = 40.169 (aspherical surface) d ₁₇ = 2.06 n _d9 = 1.56384 ν _d9 = 60.67
r ₁₈ = -3.967 d ₁₈ = 2.52
r ₁₉ = ∞ (image plane)
Zoom interval ┌──┬────┬────┬────┐
│f │ 1.975 │ 2.213 │ 5.703 │
├──┼────┼┼────┼────┤
│d ₈ │ 8.58 │ 7.16 │ 0.45 │
├──┼────┼┼────┼────┤
│d ₁₆ │ 0.23 │ 0.57 │ 5.30 │
└──┴────┴┴────┴────┘
Aspheric coefficient 10th surface K = 0.000
A ₄ = -6.90936 × 10 ^-3
A ₆ = -2.33335 × 10 ^-4
A ₈ = -3.03337 × 10 ^-4
A ₁₀ = 4.13358 × 10 ^-5
Surface 12 K = 0.000
A ₄ = 3.78672 × 10 ^-3
A ₆ = -7.39104 × 10 ^-4
A ₈ = 9.77894 × 10 ^-4
A ₁₀ = 6.87146 × 10 ^-6
Surface 17 K = 0.000
A ₄ = -1.32840 × 10 ^-2
A ₆ = -5.56828 × 10 ^-4
A ₈ = -1.76574 × 10 ^-4
A ₁₀ = 5.44032 × 10 ⁻⁵ .

Example 11
f = 2.635-4.487-7.620
F _NO = 2.31 to 2.93 to 4.00
ω = 37.9 ° to 24.0 ° to 15.8 °
r ₁ = 12.619 d ₁ = 0.57 n _d1 = 1.69680 ν _d1 = 55.53
r ₂ = 4.093 d ₂ = 2.07
r ₃ = 15.510 d ₃ = 0.42 n _d2 = 1.78590 ν _d2 = 44.20
r ₄ = 4.063 (aspherical surface) d ₄ = 1.50
r ₅ = 8.342 d ₅ = 1.27 n _d3 = 1.80518 ν _d3 = 25.42
r ₆ = 61.897 d ₆ = (variable)
r ₇ = ∞ (aperture) d ₇ = 0.42
r ₈ = 5.236 (aspherical surface) d ₈ = 2.36 n _d4 = 1.60311 ν _d4 = 60.64
r ₉ = -11.121 d ₉ = 0.30
r ₁₀ = 5.726 d ₁₀ = 2.08 n _d5 = 1.61272 ν _d5 = 58.72
r ₁₁ = -6.055 d ₁₁ = 0.30 n _d6 = 1.74077 ν _d6 = 27.79
r ₁₂ = 2.955 d ₁₂ = 2.06
r ₁₃ = 9.461 d ₁₃ = 0.61 n _d7 = 1.60342 ν _d7 = 38.03
r ₁₄ = 10391.820 d ₁₄ = (variable)
r ₁₅ = 6.809 (aspherical surface) d ₁₅ = 1.07 n _d8 = 1.56384 ν _d8 = 60.67
r ₁₆ = -29.066 d ₁₆ = 2.38
r ₁₇ = ∞ (image plane)
Zoom interval ┌──┬────┬────┬────┐
│f │ 2.635 │ 4.487 │ 7.620 │
├──┼────┼┼────┼────┤
│d ₆ │ 9.05 │ 3.73 │ 0.60 │
├──┼────┼┼────┼────┤
│d ₁₄ │ 0.60 │ 3.50 │ 8.36 │
└──┴────┴┴────┴────┘
Aspheric coefficient 4th surface K = 0.000
A ₄ = -2.63379 × 10 ^-3
A ₆ = -2.53552 × 10 ^-5
A ₈ = -9.03111 × 10 ^-6
A ₁₀ = -3.56959 × 10 ^-8
8th surface K = 0.000
A ₄ = -1.28320 × 10 ^-3
A ₆ = -2.03529 × 10 ^-5
A ₈ = -6.76960 × 10 ^-7
A ₁₀ = -1.22132 × ₁₀ ^-8
15th face K = 0.000
A ₄ = -1.23704 × 10 ^-3
A ₆ = 1.72577 × 10 ^-4
A ₈ = -2.38467 × 10 ^-5
A ₁₀ = 1.22142 × 10 ⁻⁶ .

  FIG. 12 shows aberration diagrams in Example 1 when focusing on infinity. In the figure, (a) is the wide-angle end, (b) is the intermediate state, and (c) is the aberration curve at the telephoto end. In each figure, SA is spherical aberration, AS is astigmatism, DT is distortion, CC indicates lateral chromatic aberration.

Moreover, the value of conditional expression (1)-(10) of the said Examples 1-11 is shown below.
Example Condition (1) Condition (2) Condition (3) Condition (4) Condition (5)
1 0.3 (h = 5) -0.19 (h = 4) 0.05 (h = 5) 1.10 1.62
2 0.1 (h = 4) -0.05 (h = 3.7) *** 1.67 1.26
3 0.2 (h = 4) -0.06 (h = 4) *** 1.30 1.26
4 0.2 (h = 6) -0.1 (h = 4) *** 1.20 2.45
5 0.4 (h = 5) *** 0.07 (h = 5) 1.18 1.81
6 *** -0.3 (h = 3) *** 1.14 1.23
7 0.3 (h = 3) *** -0.001 (h = 3) 1.18 1.81
8 0.2 (h = 4.5) -0.06 (h = 2.3) *** 1.20 2.45
9 0.4 (h = 3) -0.08 (h = 1.5) 0.1 (h = 3) 1.10 1.62
10 *** -0.2 (h = 1.2) *** 1.14 1.23
11 0.2 (h = 2.5) -0.02 (h = 1.6) *** 1.30 1.26

Example Condition (6) Condition (7) Condition (8) Condition (9) Condition (10)
1 4.17 -0.02 (h = 2.2) -0.980 3.208 7.10
2 6.35 -0.03 (h = 2.5) -0.524 4.431 6.69
3 4.95 -0.01 (h = 2.8) -0.673 4.071 6.90
4 4.59 -0.01 (h = 2.5) -0.784 3.642 9.24
5 4.48 -0.01 (h = 2.5) -0.900 3.702 10.48
6 4.34 -0.09 (h = 2.8) -1.055 2.957 2.03
7 4.48 -0.03 (h = 2) -0.901 3.702 10.44
8 4.59 -0.01 (h = 2) -0.784 3.644 9.16
9 4.17 -0.02 (h = 1.2) -0.980 3.211 7.15
10 4.34 -0.7 (h = 1.2) -1.059 2.967 2.00
11 4.95 -0.04 (h = 1) -0.673 4.065 6.93
Note) h in parentheses after the numerical values of conditions (1), (2), (3), and (7) is the height of the calculated point from the optical axis, and *** is the configuration of the embodiment. Indicates not applicable.

  The above-described zoom lens of the present invention can be used in various photographing apparatuses using an electronic image sensor such as a CCD or a CMOS sensor. The specific application example is shown below.

  An electronic camera in which the zoom lens of the present invention is incorporated as an objective optical system is shown in FIGS. 13 is a front perspective view showing the external appearance of the electronic camera 200, FIG. 14 is a rear perspective view thereof, and FIG. 15 is a cross-sectional view showing the configuration of the electronic camera 200. As shown in FIGS. 13 to 15, the electronic camera 200 includes a photographing optical system 202 having a photographing optical path 201, a finder optical system 204 having a finder optical path 203, a shutter 205, a flash 206, and a liquid crystal display monitor 207. ing. When the shirter 205 disposed on the upper portion of the camera 200 is pressed, photographing is performed through the objective lens 12 including the zoom lens (abbreviated in the drawing) of the present invention disposed as a photographing objective optical system in conjunction therewith. . An objective image formed by this photographing objective optical system is formed on an image sensor chip 62 such as a CCD via an lR (infrared) cut filter 80.

  Here, an lR cut filter 80 is additionally affixed on the image pickup element chip 62 to be integrally formed as an image pickup unit 60 and can be fitted and attached to the rear end of the lens frame 13 of the objective lens 12 with one touch. Therefore, the centering of the objective lens 12 and the image pickup device chip 62 and the adjustment of the surface interval are unnecessary, the assembly is simple, the productivity of the camera device can be improved, and the cost can be reduced. It is structured to have merit. A cover glass 14 for protecting the objective lens 12 is disposed at the tip of the lens frame 13. The zoom lens driving mechanism in the lens frame 13 is not shown.

  The object image received by the image sensor chip 62 is displayed as an electronic image on a liquid crystal display monitor 207 provided on the back of the camera via a processing unit 208 electrically connected to the terminal 66. The processing unit 208 also controls the recording unit 209 that records the object image captured by the image sensor chip 62 as electronic information. The recording means 209 may be a memory provided in the processing means 208, and is electrically connected to the processing means 208 and electronically connected to a magnetic recording medium such as a floppy disk or smart media as shown in the figure. It may be a device that writes a record.

  Further, the finder optical system 204 having the finder optical path 203 includes a finder objective optical system 210, a Porro prism 211 that erects the object image formed by the finder objective optical system 210, and the object image as an observer. And an eyepiece 212 that leads to the eyeball E. The Porro prism 211 is divided into a front portion and a rear portion, and there is a surface on which an object image is formed. A field frame 213 is disposed on the surface. This Porro prism 211 has four reflecting surfaces, and makes the object image formed by the finder objective optical system 210 an erect image.

Further, in the camera 200, the finder optical system 204 may be eliminated in order to reduce the number of parts, to make the camera 200 compact, and to reduce the cost. In this case, the observer takes a picture while looking at the liquid crystal display monitor 207.
Next, a personal computer which is an example of an information processing apparatus in which the zoom lens of the present invention is incorporated as an objective optical system is shown in FIGS. 16 is a front perspective view with the cover of the personal computer 300 opened, FIG. 17 is a sectional view of the photographing optical system 303 of the personal computer 300, and FIG. 18 is a side view of the state of FIG. As shown in FIGS. 16 to 18, the personal computer 300 includes a keyboard 301 for a writer to input information from the outside, information processing means and recording means not shown, and a monitor for displaying information to the operator. 302 and a photographing optical system 303 for photographing the operator himself and surrounding images. Here, the monitor 302 may be a transmissive liquid crystal display element that is illuminated from the back by a backlight (not shown), a reflective liquid crystal display element that reflects and displays light from the front, a CRT display, or the like. Further, in the drawing, the photographing optical system 303 is built in the upper right of the monitor 302. However, the imaging optical system 303 is not limited to the place, and may be anywhere around the monitor 302 or the keyboard 301.

  The photographing optical system 303 includes an objective lens 12 including a zoom lens (abbreviated in the drawing) of the present invention and an image sensor chip 62 that receives an image on a photographing optical path 304. These are built in the personal computer 300.

  Here, an lR cut filter 80 is additionally affixed on the image pickup element chip 62 to be integrally formed as an image pickup unit 60 and can be fitted and attached to the rear end of the lens frame 13 of the objective lens 12 with one touch. Therefore, the centering of the objective lens 12 and the image sensor chip 62 and the adjustment of the surface interval are unnecessary, and the assembly is simple. A cover glass 14 for protecting the objective lens 12 is disposed at the tip of the lens frame 13. The zoom lens driving mechanism in the lens frame 13 is not shown.

  The object image received by the image sensor chip 62 is input to the processing means of the personal computer 300 via the terminal 66 and is displayed on the monitor 302 as an electronic image. FIG. A rendered image 305 is shown. The image 305 can also be displayed on the personal computer of the communication partner from a remote location via the processing means, the Internet, or the telephone.

  Next, FIG. 19 shows a telephone which is an example of an information processing apparatus in which the zoom lens of the present invention is incorporated as a photographing optical system, particularly a portable telephone which is convenient to carry. 19A is a front view of the mobile phone 400, FIG. 19B is a side view, and FIG. 19C is a cross-sectional view of the photographing optical system 405. As shown in FIGS. 19A to 19C, the mobile phone 400 includes a microphone unit 401 that inputs an operator's voice as information, a speaker unit 402 that outputs the voice of the other party, and an operator who receives information. An input dial 403 for inputting information, a monitor 404 for displaying information such as a photographed image and a telephone number of the operator and the other party, a photographing optical system 405, an antenna 406 for transmitting and receiving communication radio waves, and an image And processing means (not shown) for processing information, communication information, input signals, and the like. Here, the monitor 404 is a liquid crystal display element. In the drawing, the arrangement positions of the respective components are not particularly limited to these. The photographing optical system 405 includes an objective lens 12 including a zoom lens (abbreviated in the drawing) of the present invention disposed on a photographing optical path 407, and an image sensor chip 62 that receives an object image. These are built in the mobile phone 400.

  Here, an lR cut filter 80 is additionally affixed on the image pickup element chip 62 to be integrally formed as an image pickup unit 60 and can be fitted and attached to the rear end of the lens frame 13 of the objective lens 12 with one touch. Therefore, the centering of the objective lens 12 and the image sensor chip 62 and the adjustment of the surface interval are unnecessary, and the assembly is simple. A cover glass 14 for protecting the objective lens 12 is disposed at the tip of the lens frame 13. The zoom lens driving mechanism in the lens frame 13 is not shown.

  The object image received by the imaging element chip 62 is input to a processing unit (not shown) via the terminal 66 and is displayed as an electronic image on the monitor 404, the communication partner monitor, or both. . Further, when transmitting an image to a communication partner, the processing means includes a signal processing function for converting information of the object image received by the image sensor chip 62 into a signal that can be transmitted.

  The above zoom lens of the present invention can be configured as follows, for example.

    [1] In order from the object side, a first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. The diaphragm moves together with the second lens group at the time of magnification. The first lens group includes, in order from the object side, a negative lens, a negative lens, and a positive lens, and the third lens group includes one lens. A lens having an aspherical surface satisfying the following conditional expression (1) in the first lens group and an aspherical surface satisfying the following conditional expression (2) in the third lens group: A zoom lens comprising:

0 <(1 / r _a1 −1 / r _m1 ) h ₁ / (n _a1 −n _a1 ′) <1 (1)
−1 <(1 / r _a3 −1 / r _m3 ) h ₃ / (n _a3 −n _a3 ′) <0 (2)
Where _ra1 is the paraxial radius of curvature of the aspheric surface I arranged in the first lens group, and _rm1 is the intersection of the aspheric surface I arranged in the first lens group with the optical axis on the aspheric surface I. The distance to the point on the optical axis at which the normal at the arbitrary point (1) between the maximum diameter of the on-axis light beam and the effective diameter including the off-axis light beam is closest to the optical axis, n _a1 is the aspherical surface I The refractive index on the object side, n _a1 ′ is the refractive index on the image side of the aspheric surface I, h ₁ is the height from the optical axis of the point (1), and ra ₃ is the aspheric surface arranged in the third lens group. The paraxial radius of curvature III, r _m3, is the effective diameter including the maximum diameter of the on-axis light beam on the aspheric surface III and the off-axis light beam from the intersection of the aspheric surface III arranged in the third lens group with the optical axis. Is the distance to the point on the optical axis at which the normal at the arbitrary point (3) between the two is closest to the optical axis, n _a3 is the refractive index on the object side of the aspheric surface III, and n _a3 ′ is the image side of the aspheric surface III Refractive index h ₃ is the height from the optical axis of the point (3).

    [2] In order from the object side, a first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. At the time of magnification, the diaphragm moves integrally with the second lens group, the third lens group is composed of one lens, and the concave surface of the spherical lens that satisfies the conditional expression (3) is included in the first lens group. A zoom lens using an aspherical lens formed by thinly applying a resin to the lens.

−0.1 <(1 / r _a1 ′ −1 / r _m1 ) h ₁ / (n _a1 −n _a1 ′) <1
... (3)
Here, r _a1 ′ is the paraxial radius of curvature of the concave surface on which the resin forming the aspheric surface I arranged in the first lens group is applied, and r _m1 is the aspheric surface arranged in the optical axis and the first lens group. The distance from the intersection of I to the point on the optical axis at which the normal at the arbitrary point (1) between the maximum diameter of the axial light beam on the aspherical surface and the effective diameter including the off-axis light beam is closest to the optical axis , n _a1 is the refractive index of the object-side aspherical, n _a1 'is the refractive index of the image-side aspherical, h ₁ is the height from the optical axis of the point (1).

    [3] In order from the object side, the first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. The diaphragm moves together with the second lens group at the time of magnification, and the first lens group includes, in order from the object side, a negative lens, air, a negative lens, air, and a positive lens, and the third lens group. Is composed of a single lens, and the second lens group includes, in order from the object side, a positive lens, a positive / negative cemented lens, and a positive lens, and satisfies the following conditional expression (4): .

_{0.4 <f 3 / f t <} 2.5 ··· (4)
However, f ₃ is the focal length, f _t of the third lens group is a focal length of the entire system at the telephoto end.

    [4] In order from the object side, the lens unit includes a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. The diaphragm moves together with the second lens group at the time of magnification, and the first lens group includes, in order from the object side, a negative lens, air, a negative lens, air, and a positive lens, and the third lens group. Is composed of a single lens, and the second lens group includes, in order from the object side, a positive lens, a positive / negative cemented lens, and a positive lens, and satisfies the following conditional expression (5): .

1.2 <f _1-N / f _2-N <2.7 (5)
However, f _1-N is the focal length, f _2-N of the most object side concave in the first lens group is the focal length of the second concave from the object side of the first lens group.

    [5] In order from the object side, the first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. The diaphragm moves together with the second lens group at the time of magnification, and the first lens group includes, in order from the object side, a negative lens, air, a negative lens, air, and a positive lens, and the third lens group. Is composed of a single lens, and the second lens group includes, in order from the object side, a positive lens, a positive / negative cemented lens, and a positive lens, and satisfies the following conditional expression (6): .

2 <f ₃ / IH <12 (6)
Here, f ₃ is the focal length of the third lens group, and IH is the image height.

    [6] In order from the object side, the first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. The diaphragm moves together with the second lens group at the time of magnification, and the first lens group includes, in order from the object side, a negative lens, air, a negative lens, air, and a positive lens, and the third lens group. Comprises a single lens, uses an aspherical surface satisfying conditional expression (7) on the most object side surface of the second lens group, and satisfies the following conditional expression (4): lens.

−1 <(1 / r _a2 −1 / r _m2 ) h ₂ / (1-n _a2 ′) <0 (7)
_{0.4 <f 3 / f t <} 2.5 ··· (4)
However, from the r _a2 paraxial curvature radius of the aspheric II which are arranged closest to the object side of the second lens unit r _{m @ 2} is the intersection of the aspherical II disposed on the optical axis and a second lens group, Up to the point on the optical axis where the normal at the arbitrary point (2) between the maximum diameter of the axial light beam on the aspherical surface 0.7 and the maximum diameter of the axial light beam is closest to the optical axis. Distance, n _a2 ′ is the refractive index of the lens disposed closest to the object side of the second lens group, h ₂ is the height of the point (2) from the optical axis, f ₃ is the focal length of the third lens group, f _t is the focal length of the entire system at the telephoto end.

    [7] In order from the object side, the first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. The diaphragm moves together with the second lens group at the time of magnification, and the first lens group includes, in order from the object side, a negative lens, air, a negative lens, air, and a positive lens, and the third lens group. Comprises a single lens, uses an aspherical surface satisfying conditional expression (7) as the most object-side surface of the second lens group, and satisfies the following conditional expression (5): lens.

−1 <(1 / r _a2 −1 / r _m2 ) h ₂ / (1-n _a2 ′) <0 (7)
1.2 <f _1-N / f _2-N <2.7 (5)
However, from the r _a2 paraxial curvature radius of the aspheric II which is disposed on the most object side in the second lens group, r _{m @ 2} is the intersection of the aspherical II disposed on the optical axis and the second lens group, Up to the point on the optical axis where the normal at the arbitrary point (2) between the maximum diameter of the axial light beam on the aspherical surface 0.7 and the maximum diameter of the axial light beam is closest to the optical axis. The distance, n _a2 ′ is the refractive index of the lens located closest to the object side of the second lens group, h _{2 is} the height of the point (2) from the optical axis, and f _1-N is the most of the first lens group The focal length of the concave lens on the object side, f _2-N is the focal length of the second concave lens from the object side of the first lens group.

    [8] In order from the object side, the lens unit includes a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. The diaphragm moves together with the second lens group at the time of magnification, and the first lens group includes, in order from the object side, a negative lens, air, a negative lens, air, and a positive lens, and the third lens group. Comprises a single lens, uses an aspherical surface satisfying conditional expression (7) on the most object side surface of the second lens group, and satisfies the following conditional expression (6): lens.

−1 <(1 / r _a2 −1 / r _m2 ) h ₂ / (1-n _a2 ′) <0 (7)
2 <f ₃ / IH <12 (6)
However, from the r _a2 paraxial curvature radius of the aspheric II which is disposed on the most object side in the second lens group, r _{m @ 2} is the intersection of the aspherical II disposed on the optical axis and the second lens group, Up to the point on the optical axis where the normal at the arbitrary point (2) between the maximum diameter of the axial light beam on the aspherical surface 0.7 and the maximum diameter of the axial light beam is closest to the optical axis. Distance, n _a2 ′ is the refractive index of the lens disposed closest to the object side of the second lens group, h ₂ is the height of the point (2) from the optical axis, f ₃ is the focal length of the third lens group, IH is the image height.

    [9] In order from the object side, the lens unit includes a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. When the magnification is doubled, the diaphragm moves integrally with the second lens group, all the lenses constituting the first lens group are meniscus lenses convex on the object side, and satisfy the following conditional expression: Zoom lens.

1.2 <f _1-N / f _2-N <2.7 (5)
However, f _1-N is the focal length, f _2-N of the most object side concave in the first lens group is the focal length of the second concave from the object side of the first lens group.

    [10] In order from the object side, the lens unit includes a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. At the time of magnifying, the diaphragm moves integrally with the second lens group, all the lenses constituting the first lens group are meniscus lenses convex toward the object side, and satisfy the following conditional expression (8): A zoom lens characterized by that.

-1.35 <f ₁ / f ₃ <−0.4 (8)
Here, f ₁ is the focal length of the first lens group and f ₃ is the focal length of the third lens group.

    [11] In order from the object side, the first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. When the lens is doubled, the diaphragm moves integrally with the second lens group, the third lens group includes one lens, and the second lens group includes a positive lens and a positive / negative cemented lens in order from the object side. A zoom lens comprising a positive lens and an aspherical surface satisfying conditional expression (7) being used as the most object side surface of the second lens group.

−1 <(1 / r _a2 −1 / r _m2 ) h ₂ / (1-n _a2 ′) <0 (7)
However, from r _a2 paraxial curvature radius of the aspheric II which is disposed on the most object side in the second lens group, r _{m @ 2} is the intersection of the aspherical II disposed on the optical axis and the second lens group, Up to the point on the optical axis where the normal at the arbitrary point (2) between the maximum diameter of the axial light beam on the aspherical surface 0.7 and the maximum diameter of the axial light beam is closest to the optical axis. The distance, n _a2 ′, is the refractive index of the lens arranged closest to the object side in the second lens group, and h ₂ is the height from the optical axis of the point (2).

    [12] In order from the object side, the lens unit includes a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. When the lens is doubled, the diaphragm moves integrally with the second lens group, the third lens group includes one lens, and the second lens group includes a positive lens and a positive / negative cemented lens in order from the object side. A zoom lens comprising a positive lens, wherein the lens closest to the image plane in the second lens group is a meniscus lens convex toward the image plane, and satisfies the following conditional expression (9):

2.7 <Σ _2g /IH<4.7 (9)
However, Σ _2g is the distance on the optical axis from the aperture stop to the surface closest to the image plane of the second lens group, and IH is the image height.

    [13] In order from the object side, the lens unit includes a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. When the lens is doubled, the diaphragm moves integrally with the second lens group, the third lens group includes one lens, and the second lens group includes a positive lens and a positive / negative cemented lens in order from the object side. A zoom lens comprising a positive lens, wherein the lens closest to the image plane in the second lens group is a meniscus lens convex toward the image plane, and satisfies the following conditional expression (4):

_{0.4 <f 3 / f t <} 2.5 ··· (4)
However, f ₃ is the focal length, f _t of the third lens group is a focal length of the entire system at the telephoto end.

    [14] In order from the object side, the lens unit includes a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. When the lens is doubled, the diaphragm moves integrally with the second lens group, the third lens group includes one lens, and the second lens group includes a positive lens and a positive / negative cemented lens in order from the object side. A positive lens, the most image side lens of the second lens group is a meniscus lens convex to the image side, and at least two lenses from the most object side of the first lens group are negative lenses. Yes, satisfying the following conditional expression (5) Zoom lens.

1.2 <f _1-N / f _2-N <2.7 (5)
However, f _1-N is the focal length, f _2-N of the most object side concave in the first lens group is the focal length of the second concave from the object side of the first lens group.

    [15] In order from the object side, the first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. When the lens is doubled, the diaphragm moves integrally with the second lens group, the third lens group includes one lens, and the second lens group includes a positive lens and a positive / negative cemented lens in order from the object side. A zoom lens comprising a positive lens, wherein the lens closest to the image plane in the second lens group is a meniscus lens convex toward the image plane, and satisfies the following conditional expression (6).

2 <f ₃ / IH <12 (6)
Here, f ₃ is the focal length of the third lens group, and IH is the image height.

    [16] In order from the object side, the first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. When the lens is doubled, the diaphragm moves integrally with the second lens group, the third lens group includes one lens, and the second lens group includes a positive lens and a positive / negative cemented lens in order from the object side. A zoom lens comprising: a positive lens, wherein a thickness ratio of the positive lens to the negative lens of the cemented lens satisfies the following conditional expression (10) and satisfies the following conditional expression (4): .

_{1. 9 <d ce1 / d ce2} <12 (10)
_{0.4 <f 3 / f t <} 2.5 ··· (4)
However, d _ce1 the thickness of the convex lens of the cemented lens in the second lens group, d _ce2 the thickness of the concave lens of the cemented lens in the second lens group, f ₃ is the focal length of the third lens group, f _t the telephoto end This is the focal length of the entire system.

    [17] In order from the object side, the first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. When the lens is doubled, the diaphragm moves integrally with the second lens group, the third lens group includes one lens, and the second lens group includes a positive lens and a positive / negative cemented lens in order from the object side. And the ratio of the thickness of the positive lens to the negative lens of the cemented lens satisfies the following conditional expression (10), and at least two lenses from the most object side of the first lens group are negative: And satisfy the following conditional expression (4) The zoom lens according to claim.

_{1. 9 <d ce1 / d ce2} <12 (10)
1.2 <f _1-N / f _2-N <2.7 (5)
However, d _ce1 the thickness of the convex lens of the cemented lens in the second lens group, d _ce2 the thickness of the concave lens of the cemented lens in the second lens group, f _1-N is of the most object side concave in the first lens group focal length, f _2-N is the focal length of the second concave from the object side of the first lens group.

    [18] In order from the object side, the lens includes a first lens group having negative power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. When the lens is doubled, the diaphragm moves integrally with the second lens group, the third lens group includes one lens, and the second lens group includes a positive lens and a positive / negative cemented lens in order from the object side. A zoom lens comprising: a positive lens, wherein a ratio of the thickness of the positive lens to the negative lens of the cemented lens satisfies the following conditional expression (10) and satisfies the following conditional expression (6): .

_{1. 9 <d ce1 / d ce2} <12 (10)
2 <f ₃ / IH <12 (6)
However, d _ce1 the thickness of the convex lens of the cemented lens in the second lens group, d _ce2 the thickness of the concave lens of the cemented lens in the second lens group, f ₃ is the focal length of the third lens group, the IH is image height is there.

    [19] In order from the object side, the first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power. The lens group moves on the optical axis, and the third lens group is fixed and the respective intervals of the first lens group, the second lens group, and the third lens group are changed to perform zooming. The aperture moves together with the second lens group at the time of magnification, and the first lens group includes, in order from the object side, a negative lens, a negative lens, and a positive lens, and the third lens group has a conditional expression ( A zoom lens comprising one lens having an aspheric surface on the object side that satisfies 2).

−1 <(1 / r _a3 −1 / r _m3 ) h ₃ / (n _a3 −n _a3 ′) <0 (2)
However, r _a3 is a paraxial radius of curvature of the aspherical surface III which is disposed in the third lens group, r _m3 is from the intersection of the aspherical III disposed on the optical axis and the third lens group, the aspherical surface III The distance to the point on the optical axis at which the normal at the arbitrary point (3) between the maximum diameter of the on-axis light beam and the effective diameter including the off-axis light beam is closest to the optical axis, _na3 is the aspherical surface III The refractive index on the object side, n _a3 ′ is the refractive index on the image side of the aspheric surface III, and h ₃ is the height of the point (3) from the optical axis.

It is sectional drawing in the wide angle end of the zoom lens of Example 1 of this invention. It is sectional drawing in the wide angle end of the zoom lens of Example 2 of this invention. It is sectional drawing in the wide-angle end of the zoom lens of Example 3 of this invention. It is sectional drawing in the wide angle end of the zoom lens of Example 4 of this invention. It is sectional drawing in the wide angle end of the zoom lens of Example 5 of this invention. It is sectional drawing in the wide angle end of the zoom lens of Example 6 of this invention. It is sectional drawing in the wide angle end of the zoom lens of Example 7 of this invention. It is sectional drawing in the wide-angle end of the zoom lens of Example 8 of this invention. It is sectional drawing in the wide angle end of the zoom lens of Example 9 of this invention. It is sectional drawing in the wide angle end of the zoom lens of Example 10 of this invention. It is sectional drawing in the wide angle end of the zoom lens of Example 11 of this invention. FIG. 6 is an aberration diagram for Example 1 upon focusing on infinity. 1 is a front perspective view showing an external appearance of an electronic camera in which a zoom lens of the present invention is incorporated as an objective optical system. 1 is a rear perspective view of an electronic camera in which a zoom lens of the present invention is incorporated as an objective optical system. It is sectional drawing which shows the structure of the electronic camera in which the zoom lens of this invention was integrated as an objective optical system. It is the front perspective view which opened the cover of the personal computer in which the zoom lens of this invention was integrated as an objective optical system. It is sectional drawing of the imaging optical system of a personal computer. It is a side view of the state of FIG. 1 is a front view, a side view, and a sectional view of a photographing optical system of a mobile phone in which a zoom lens according to the present invention is incorporated as an objective optical system.

Explanation of symbols

G1 ... first group G2 ... second group G3 ... second group E ... observer eyeball 12 ... objective lens 13 ... lens frame 14 ... cover glass 60 ... imaging unit 62 ... imaging element chip 66 ... terminal 80 ... lR cut filter 200 ... Electronic camera 201 ... Shooting optical path 202 ... Shooting optical system 203 ... finder optical path 204 ... finder optical system 205 ... shutter 206 ... flash 207 ... liquid crystal display monitor 208 ... processing means 209 ... recording means 210 ... finder objective optical system 211 ... Porro prism 212 ... Eyepiece lens 213 ... Field frame 300 ... Personal computer 301 ... Keyboard 302 ... Monitor 303 ... Shooting optical system 304 ... Shooting optical path 305 ... Image 400 ... Mobile phone 401 ... Microphone part 402 ... Speaker part 403 ... Input dial 404 ... Monitor 405 ... Shooting optical system 406 ... Antenna 07 ... photographing optical path

Claims (7)

In order from the object side, a first lens group having a negative power, an aperture stop, a second lens group having a positive power, and a third lens group having a positive power, and the first lens group and the second lens group are The zooming is performed by moving on the optical axis, and fixing the third lens group and changing the respective intervals of the first lens group, the second lens group, and the third lens group. stop is moved together with the second lens group, the first lens group comprises, in order from the object side, a negative lens, air, a negative lens, air, a positive lens, the second lens group, the object In order from the side, a positive lens, a positive / negative cemented lens, and a positive lens are formed, and the ratio of the thickness of the positive lens to the negative lens of the cemented lens satisfies the following conditional expression (10), and the third lens: The group consists of one lens, the most of the second lens group Camera using an aspherical surface which satisfies the condition on the surface of the side equation (7 '), and, equipped with a zoom lens and an electronic imaging device and satisfies the following conditional expression (5).
_{1. 9 <d ce1 / d ce2} <12 (10)
−1 <(1 / r _a2 −1 / r _m2 ) h ₂ / (1-n _a2 ′) ≦ −0.01
... (7 ')
1.2 <f _1-N / f _2-N <2.7 (5)
However, d _ce1 the thickness of the convex lens of the cemented lens in the second lens group, d _ce2 the thickness of the concave lens of the cemented lens in the second lens group, r _a2 is located on the most object side of the second lens group The paraxial radius of curvature, r _m2 , of the aspheric surface II is 0.7 times the maximum diameter of the axial light beam on the aspheric surface II from the intersection of the optical surface and the aspheric surface II arranged in the second lens group. Is the distance to the intersection of the normal and the optical axis at an arbitrary point (2) between the axis and the maximum diameter of the on-axis light beam, and is closest to the normal if the normal and the optical axis pass each other The distance to the point on the optical axis, n _a2 ′ is the refractive index of the lens disposed closest to the object side in the second lens group, h ₂ is the height of the point (2) from the optical axis, and f _{1− N} is the focal length of the concave lens closest to the object side of the first lens group, and f _2-N is the focal length of the second concave lens from the object side of the first lens group. The most image side lens in the second lens group is convex meniscus lens on the image side, a zoom lens and an electronic imaging device according to claim 1, characterized by satisfying the following conditional expression (9) Camera provided.
2.7 <Σ _2g /IH<4.7 (9)
However, Σ _2g is the distance on the optical axis from the aperture stop to the surface closest to the image plane of the second lens group, and IH is the image height. 3. The zoom lens and electronic imaging according to claim 1, wherein the lens closest to the image plane in the second lens group is a meniscus lens convex toward the image plane, and satisfies the following conditional expression (4): Camera with elements.
_{0.4 <f 3 / f t <} 2.5 ··· (4)
However, f ₃ is the focal length, f _t of the third lens group is a focal length of the entire system at the telephoto end. The most image side lens in the second lens group including a zoom lens and an electronic imaging device according to any one of claims 1 to 3, characterized in that Ru meniscus lens der convex on the image surface side camera. The most image side lens in the second lens group is a convex meniscus lens on the image side, according to any one of claims 1 4, characterized by satisfying the following conditional expression (6) A camera equipped with a zoom lens and an electronic image sensor.
2 <f ₃ / IH <12 (6)
Here, f ₃ is the focal length of the third lens group, and IH is the image height. Camera equipped with a zoom lens and an electronic imaging device according to any one of claims 1 to 5, characterized by satisfying conditional expression below (4).
_{0.4 <f 3 / f t <} 2.5 ··· (4)
However, f ₃ is the focal length, f _t of the third lens group is a focal length of the entire system at the telephoto end. Camera equipped with a zoom lens and an electronic imaging device according to any one of claims 1 to 6, characterized in that satisfies conditional expression below (6).
2 <f ₃ / IH <12 (6)
Here , f ₃ is the focal length of the third lens group, and IH is the image height.

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