JP2012002901A - Zoom lens and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize the size of a device by suppressing an occurrence of chromatic aberration in a zoom lens with a wide angle and high variable power ratio.SOLUTION: The zoom lens has: a positive first group of lenses G1 which are fixed when varying power; a second group of lenses G2 having negative refractive power which are monotonously moved in the direction of an optical axis when varying power; and a subsequent group of lenses Ge having positive refractive power as a whole in this order from the object side. In this case, the first group of lenses G1 has: a first group first lens section G11 comprising two or less lenses both having negative refractive power; a first group second lens section G12 having two lenses which are a positive lens having a convex surface facing the image side and a negative meniscus lens having a concave surface facing the object side arranged in this order from the object side; and a first group third lens section G13 with one negative lens and at least two positive lenses consecutively arranged in this order from the object side.

Description

  The present invention relates to a zoom lens having a wide-angle and high zoom ratio and an imaging device including the zoom lens.

  In recent years, many zoom lenses used in consumer video cameras and the like having a field angle of about 60 degrees when the zoom setting is set at the wide angle end and a zoom ratio of about 10 times have been commercialized. In such a zoom lens, as a first lens group, a lens having a negative refractive power (hereinafter also referred to as a negative lens or a negative lens) in order from the object side has two or three positive refractive powers. Many lenses having a lens (hereinafter also referred to as a positive lens or a positive lens) are known.

  In the case of a zoom lens that requires a larger angle of view, a wide conversion lens is attached to a general zoom lens having an angle of view of about 60 degrees, or the wide conversion lens is supported. A lens portion consisting of a plurality of negative lenses and positive lenses and forming a substantially afocal system as a whole is disposed on the object side of the first lens group of a general zoom lens having a field angle of about 60 degrees. A method of constructing a zoom lens having a large angle of view is also known.

  As such a zoom lens, for example, a zoom lens having a wide angle of view and a wide conversion lens having a simple configuration including one negative lens and one positive lens is known (Patent Document). 1).

  A wide conversion lens is generally mounted on the object side of a master lens that can be used as a single unit, and shortens the focal length of the master lens. However, when it is not necessary to separate the wide conversion lens from the master lens, it is more advantageous to reduce the size by designing an optimized zoom lens with the wide conversion lens and the master lens integrated ( Patent Document 2).

  Furthermore, there is a growing demand for zoom lenses (wide-angle high zoom ratio zoom lenses) that have a wide angle but a large magnification at the telephoto end (long focal length). A problem in increasing the zoom ratio is correction of axial chromatic aberration that occurs when the zoom setting is set to the telephoto side. It is also important to balance the lateral chromatic aberration that occurs when the zoom setting is set on the wide-angle side and the axial chromatic aberration that occurs when the zoom setting is set on the telephoto side. The first lens group is mainly responsible for correcting the longitudinal chromatic aberration when the zoom setting is set to the telephoto side, and the object side lens portion in the first lens group is composed of two lenses, a positive lens and a negative lens. With such a simple configuration, it is difficult to satisfactorily correct axial chromatic aberration and lateral chromatic aberration.

  For this reason, a wide-angle high zoom ratio zoom lens in which the lens portion on the object side in the first lens group is composed of three to four lenses to correct axial chromatic aberration and lateral chromatic aberration is also known ( (See Patent Documents 3 to 5). For example, a wide-angle high zoom ratio zoom lens (see Patent Document 3) in which a negative lens, a negative lens, a positive lens,... Are arranged in order from the object side, a negative lens, a negative lens, a negative lens, in order from the object side. A wide-angle high zoom ratio zoom lens (see Patent Document 4) in which a positive lens is arranged, and a wide-angle high zoom ratio zoom lens in which a negative lens, a negative lens, a positive lens, and a positive lens are arranged in this order from the object side ( Patent Document 5) is known.

  In such a wide-angle high zoom ratio zoom lens, two negative lenses are continuously arranged on the most object side. The two negative lenses are arranged continuously on the most object side because the strong negative power necessary for widening the angle is dispersed and handled by the two negative lenses, and the light rays that pass through the lens are sharply refracted. This is to suppress the occurrence of aberrations by suppressing the above. On the other hand, there is no wide-angle high zoom ratio zoom lens in which a negative lens and a positive lens are continuously arranged closest to the object side, such as a negative lens, a positive lens, a negative lens,. The reason why there is no wide-angle, high-magnification zoom lens with such a configuration is because of the large chromatic aberration caused by the refraction of the off-axis light beam incident at a large angle with respect to the optical axis of the zoom lens at a steep angle. This is because it is difficult to correct.

  Further, wide-angle, high zoom ratio zoom lenses used in video cameras, surveillance cameras, and the like are often used in a 4-group or 5-group configuration. The first lens group of such a zoom lens has 1 In general, two negative lenses, two to three positive lenses are arranged in this order from the object side. Most of the one negative lens is made of a high dispersion material having an Abbe number of about 25, and it is rare to use an optical member that deviates from the Abbe number.

Further, if it is intended to realize further high zooming by using a high dispersion material for the negative lens constituting the first lens group, it is very difficult to correct the secondary spectrum of chromatic aberration. In a zoom lens having a zoom ratio of 10 times or less, the secondary spectrum of chromatic aberration can be corrected even if a high dispersion material is used for the negative lens constituting the first lens group, and a high refractive index and high dispersion material is used. The advantage of using a thin lens is great. On the other hand, in order to further reduce the secondary spectrum of the chromatic aberration, there is an example in which a material having a slightly smaller dispersion than the above high dispersion material is used for the negative lens constituting the first lens group. For example, although the Abbe number is known example of application of the 30 to 40 degree material for the negative lens constituting the first lens unit (see Patent Document 6-8), both in zoom ratio of 10 times or less In order to make the zoom ratio larger than that, it is necessary to improve the configuration and power distribution of the first lens group.

  By the way, in order to realize a wide angle in addition to the above high zoom ratio, it is possible to dispose a lens group having an afocal system having a configuration similar to a wide conversion lens on the object side of the first lens group. It is known to be effective (see Patent Documents 6 to 8). When the zoom lens is configured in this way, the axial chromatic aberration that occurs when the zoom setting is set at the telephoto end can be reduced by the amount that the focal length is shortened when the zoom setting is set at the wide-angle end. Even if it is slightly large, the secondary spectrum of chromatic aberration can be corrected to a desired level. When configuring a zoom lens in this way, there are many examples in which a lens made of an optical member having an Abbe number of about 25 is employed with respect to the negative lens constituting the first lens group (see Patent Document 9).

JP-A-6-138389 Japanese Patent No. 3033276 Japanese Patent No. 3667054 JP 2006-119346 A JP 2009-316288 A JP 2003-98434 A JP 2005-345892 A Japanese Patent Laid-Open No. 2007-3600 JP 2007-316287 A

  By the way, a wide-angle high zoom ratio zoom lens (see Patent Documents 1 to 5) that realizes a wide angle and a high zoom ratio while suppressing chromatic aberration is an object side in the first lens group (that is, in the first lens group). A large gap (air space) is provided between the lenses arranged in the portion corresponding to the wide conversion lens. Therefore, in such a wide-angle high zoom ratio zoom lens, there is a problem that the first lens group becomes large. Further, since such a large gap is provided, there is a problem that the diameter of the lens (front lens) closest to the object side becomes very large.

  Therefore, in such a wide-angle high zoom ratio zoom lens, it is desired to reduce the size of the apparatus without increasing the occurrence of chromatic aberration, that is, while suppressing the occurrence of lateral chromatic aberration on the wide-angle side and axial chromatic aberration on the telephoto side. There is a request.

  On the other hand, the zoom ratio (see Patent Documents 6 to 9) using an optical member having an Abbe number of about 30 to 40 to correct the secondary spectrum of chromatic aberration is further increased, for example, 15 to 20 times. If an attempt is made to make it large, correction of the secondary spectrum of chromatic aberration becomes difficult again. Here, if an optical member with smaller dispersion is applied to the negative lens constituting the first lens group, the curvature of the lens must be increased, and the zoom lens becomes larger. In addition, when an optical member having such a small dispersion is applied to suppress chromatic aberration, it is difficult to achieve both correction of the secondary spectrum of chromatic aberration and correction of off-axis chromatic aberration. Therefore, in order to widen the zoom lens, to increase the zoom ratio, and to reduce the size of the zoom lens, it is necessary to optimize the optical member used for the negative lens constituting the first lens group and the lens configuration of the first lens group. is there.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a zoom lens and an imaging apparatus with a wide angle and high zoom ratio that can reduce the size of the apparatus while suppressing the occurrence of chromatic aberration. It is.

  The first zoom lens of the present invention includes, in order from the object side, a first lens group having a positive refractive power that is fixed during zooming, and a first lens group having a negative refractive power that monotonously moves in the optical axis direction during zooming. The first lens group includes two lens groups, a subsequent lens group having a positive refractive power as a whole, and the first lens group is composed of two or less lenses each having a negative refractive power in order from the object side. Only the first lens unit, the second lens unit, and the negative lens unit are arranged in this order from the object side: a positive lens with a convex surface facing the image side, and a negative meniscus lens with a concave surface facing the object side. The lens includes at least two positive lenses having a first lens group third lens portion that is continuously arranged in this order from the object side.

  The Abbe number νd12n based on the d-line of the optical member forming the meniscus lens preferably satisfies the conditional expression (a): 30 <νd12n <55, and the conditional expression (a ′): 35 < It is more desirable to satisfy νd12n <57.

  In the first zoom lens, when the radius of curvature of the object side lens surface of the negative meniscus lens constituting the first lens unit second lens portion is R12f and the radius of curvature of the image side lens surface is R12r, the conditional expression ( b): −5.0 <(R12f + R12r) / (R12f−R12r) <− 1.0 is preferably satisfied, and conditional expression (b ′): −4.5 <(R12f + R12r) / (R12f It is more desirable to satisfy -R12r) <-1.3.

  The Abbe number νd13n based on the d-line of the optical member forming the negative lens disposed in the first lens unit third lens portion satisfies the conditional expression (c): 22 <νd13n <38. Desirably, it is more desirable to satisfy the conditional expression (c ′): 23 <νd13n <32.

  The positive lens constituting the first lens unit second lens part and the negative meniscus lens are cemented, and the negative lens constituting the first lens group third lens part is disposed adjacent to the negative lens. It is desirable that the positive lens is joined.

  The first zoom lens has a distance (air interval / optical axis) between the most image side lens surface constituting the first group first lens unit and the most object side lens surface constituting the first group second lens unit. D1), the distance between the most object side lens surface constituting the first lens unit first lens part and the most image side lens surface constituting the first group second lens part (distance on the optical axis). When d is dL, it is desirable that conditional expression (d): 0.15 <d1 / dL <0.55 is satisfied, and conditional expression (d ′): 0.18 <d1 / dL <0 .52 is more desirable.

  The interval d1 is a distance on the optical axis between the lens surfaces and is also an air interval. Further, the distance dL is a distance on the optical axis between the lens surfaces.

  The first lens group first lens portion may be composed of one negative lens.

  The second zoom lens of the present invention includes, in order from the object side, a first lens group having a positive refractive power that is fixed during zooming, and a first lens group having a negative refractive power that monotonously moves in the optical axis direction during zooming. Two lens groups, and a subsequent lens group having a positive refractive power as a whole. The first lens group has one negative lens, two to three positive lenses arranged in this order from the object side in this order. The first group A part, and conditional expression (e): 27 <νd1mn <45, conditional expression (f): 2.3 <| f1mn | / f1m <4.5, conditional expression (g): 1.8 <f1m / (fw × ft) 1/2 <3.1 and conditional expression (h): 55 <νd1m + <75 are all satisfied.

In the second zoom lens, conditional expression (e ′): 27 <νd1mn <43, conditional expression (f ′): 2.3 <| f1mn | / f1m <4.3, conditional expression (g ′) : 2.0 <f1m / (fw × ft) ^1/2 <3.0, conditional expression (h ′): It is more preferable to satisfy all of 56 <νd1m + <72.

  Where νd1mn is the Abbe number based on the d-line of the optical member forming one negative lens arranged in the first group A section, and f1mn is the one negative lens arranged in the first group A section. , F1m is the focal length of the entire first lens unit A, fw is the focal length of the entire zoom lens when the zoom setting is set at the wide angle end, and ft is the zoom lens when the zoom setting is set at the telephoto end. The focal length of the entire system, νd1m +, is an average value with respect to the Abbe number with respect to the d-line of the optical member forming each positive lens arranged in the first group A section.

  The Abbe number νd1mp based on the d-line of the optical member forming the positive lens adjacent to the negative lens disposed in the first group A portion satisfies the conditional expression (i): 55 <νd1mp <70. It is desirable to satisfy the conditional expression (i ′): 57 <νd1mp <70.

  The first lens group includes a first group B portion having one or more negative lenses and one or more positive lenses on the object side of the first group A portion. The negative lens is disposed closest to the object side, and the Abbe number νd1kn based on the d-line of the optical member forming the negative lens satisfies the conditional expression (j): 35 <νd1kn <55. It is desirable to satisfy the condition (j ′): 37 <νd1kn <55.

  The Abbe number νd1kp based on the d-line of the optical member forming any one of the positive lenses disposed in the first group B portion satisfies the conditional expression (k): 60 <νd1kp. Desirably, it is more desirable to satisfy the conditional expression (k ′): 62 <νd1kp. Note that any one of the positive lenses arranged in the first group B portion is at least one positive lens among the positive lenses arranged in the first group B portion.

  The first group B part preferably has a negative meniscus lens having a concave surface facing the object side.

  In the first and second zoom lenses, when the focal length of the first lens unit is f1, the focal length of the entire zoom lens system at the wide angle end is fw, and the focal length of the entire zoom lens system at the telephoto end is ft. It is desirable that the conditional expression (m) satisfies 1.9 <f1 / (fw × ft) 1/2 <3.1, and the conditional expression (m ′): 2.0 <f1 / (fw Xft) It is more desirable to satisfy 1/2 <3.0.

  Subsequent lens groups of the first and second zoom lenses are an aperture, a third lens group having a positive refractive power that is fixed at the time of zooming, and a position of the image plane that is moved at the time of zooming. It is desirable to include a fourth lens group having a positive refractive power for correcting and focusing the fluctuation.

  The subsequent lens group may include only the third lens group and the fourth lens group.

  In the first and second zoom lenses, conditional expression (n): 2.5 <f3 / f4 <5, where f3 is the focal length of the third lens group and f4 is the focal length of the fourth lens group. 0.0 is preferable, and it is more preferable that conditional expression (n ′): 2.6 <f3 / f4 <4.8 is satisfied.

  An imaging apparatus according to the present invention includes the first or second zoom lens.

  In the first and second zoom lenses of the present invention, zooming of the zoom lens is executed by moving the second lens group monotonously in the optical axis direction.

  Note that moving the lens group monotonically means that the lens group is moved only in one direction when the magnification is increased, and the lens group is moved in one direction when the magnification is decreased. Means moving only in the opposite opposite direction.

  Further, “one negative lens, two to three positive lenses (or at least two positive lenses) are sequentially arranged in this order from the object side” means one negative lens, two to three It means that one positive lens (or at least two positive lenses) is arranged so as not to include other lenses other than these lenses.

  As for the number of lenses in the case of including a cemented lens, the number of lenses is counted assuming that a cemented lens formed by cementing n lenses is composed of n lenses.

  The lens group is not limited to a plurality of lenses, and may be a lens.

  The radius of curvature is positive when convex on the object side and negative when convex on the image side.

  Further, the Abbe number ν of the optical member with respect to the d-line is a value obtained by the equation ν = (Nd−1) / (NF−NC). However, the refractive index of the optical member for NF: F line (486.1 nm), the refractive index of the optical member for Nd: d line (587.6 nm), and the refractive index of the optical member for NC: C line (656.3 nm). is there.

  According to the first zoom lens and the imaging apparatus of the present invention, in order from the object side, the first lens group having a positive refractive power that is fixed at the time of zooming, and the second lens group having a negative refractive power that is moved at the time of zooming. The first lens unit includes a lens group and a subsequent lens group having a positive refractive power as a whole, and the first lens group is composed of two or less lenses having negative refractive power in order from the object side. A first lens, a second lens unit, and a single negative lens, in which only a positive lens having a convex surface facing the image side and a negative meniscus lens having a concave surface facing the object side are arranged in this order from the object side, Since at least two positive lenses have the first lens group third lens portion continuously arranged in this order from the object side, it is possible to reduce the size of the apparatus while suppressing the occurrence of chromatic aberration.

  More specifically, this zoom lens includes a first lens group first lens unit having negative refractive power, a first lens group second lens unit in which two lenses, a positive lens and a negative meniscus lens, are arranged in this order. To achieve a wider angle. Since the chromatic aberration generated through the first lens group first lens portion and the first lens group second lens portion is canceled by the first lens group third lens portion, the chromatic aberration can be achieved without increasing the size of the first lens group. Can be corrected satisfactorily.

  Here, the first group first lens portion and the first group second lens portion (hereinafter also referred to as wide angle lens portion) for widening the angle of the present invention are the negative lens, the positive lens, the negative lens from the most object side. It can be considered that the lenses are arranged in the order of the lenses. On the other hand, a conventionally known wide-angle lens unit is arranged so that lenses are arranged in the order of a negative lens, a negative lens, and a positive lens from the most object side. For this reason, the wide-angle lens unit generates larger chromatic aberration than the conventional wide-angle lens unit. However, the wide-angle lens unit in the first zoom lens according to the present invention once generates such chromatic aberration. deep.

  The chromatic aberration generated in the wide-angle lens unit can be canceled by passing through the first group third lens unit.

  That is, since the first lens unit third lens unit has a negative lens and a positive lens in this order from the object side, a positive lens having a convex surface on the image side and a negative meniscus lens having a concave surface on the object side are provided. A chromatic aberration characteristic capable of canceling chromatic aberration generated through the wide-angle lens unit including the first lens unit second lens unit arranged in this order from the object side can be imparted to the first lens unit third lens unit. Accordingly, it is possible to cancel the chromatic aberration generated through the first group first lens portion and the first group second lens portion through the first group third lens portion without increasing the size of the first lens group.

  According to the second zoom lens and the imaging apparatus of the present invention, in order from the object side, the first lens group having a positive refractive power that is fixed at the time of zooming, the negative lens that moves monotonously in the optical axis direction at the time of zooming A second lens group having a refractive power and a subsequent lens group having a positive refractive power as a whole; the first lens group is composed of one negative lens, and two to three positive lenses in this order from the object side. Since the first group A portion is arranged continuously and all the conditional expressions (e) to (h) are satisfied, it is possible to suppress the occurrence of chromatic aberration in a zoom lens having a wide angle and high zoom ratio, thereby reducing the size of the apparatus. It can be downsized. That is, it is possible to reduce the size of the zoom lens having a wide angle and high zoom ratio while performing both the correction of the secondary spectrum of chromatic aberration and the correction of off-axis chromatic aberration.

  Here, the conditional expression (e) defines the Abbe number of the negative lens arranged in the first group A section.

  If the zoom lens is configured to fall below the lower limit of the conditional expression (e), the refractive power of the negative lens and the positive lens disposed adjacent to the negative lens becomes weak, which is advantageous for correcting spherical aberration and the like. However, it becomes difficult to correct the secondary spectrum well.

  On the other hand, if the zoom lens is configured to exceed the upper limit of conditional expression (e), the difference in dispersion from the positive lens will be small, and the on-axis when the zoom setting is set near the telephoto end. It becomes difficult to correct chromatic aberration, and the refractive power of each lens becomes too strong, making it difficult to correct spherical aberration. Further, there arises a problem that the curvature of the lens becomes large and the lens system becomes large.

  Therefore, if the zoom lens is configured so as to satisfy the conditional expression (e), occurrence of such a problem can be suppressed.

  Note that “determining the zoom setting near the telephoto end” means including the case where the zoom setting is determined at the telephoto end.

  Conditional expression (f) defines the relationship between the focal length of the negative lens disposed in the first group A section and the focal length of the first group A section.

  If the zoom lens is configured to fall below the lower limit of the conditional expression (f), the refractive power of the negative lens becomes too strong, making it difficult to correct various aberrations and increasing the curvature of field.

  On the contrary, if the upper limit of conditional expression (f) is exceeded, the refractive power of the negative lens becomes weak and chromatic aberration (particularly primary chromatic aberration) cannot be corrected sufficiently.

  Therefore, if the zoom lens is configured to satisfy the conditional expression (f), occurrence of such a problem can be suppressed.

  Conditional expression (g) defines the relationship between the focal length of the first lens unit A and the focal length of the entire system at the wide-angle end and the telephoto end.

  If the zoom lens is configured so as to fall below the lower limit of the conditional expression (g), the power of the first lens group becomes too strong, and it becomes difficult to correct various aberrations such as spherical aberration.

  On the other hand, if the zoom lens is configured so as to exceed the upper limit of the conditional expression (g), the power of the first lens group becomes weak, so that the entire length of the optical system becomes long.

  Therefore, if the zoom lens is configured so as to satisfy the conditional expression (g), occurrence of such a problem can be suppressed.

  Conditional expression (h) defines the range of the average value for the Abbe number of each of the two to three positive lenses disposed in the first group A section.

  If the zoom lens is configured to fall below the lower limit of the conditional expression (h), it becomes difficult to correct chromatic aberration, particularly axial chromatic aberration at the telephoto end.

  Contrary to this, if the zoom lens is configured to exceed the upper limit of conditional expression (h), it is advantageous for chromatic aberration correction, but the curvature of the lens surface of any positive lens becomes large, There arises a problem that the zoom lens is enlarged. In particular, when a material that satisfies the conditional expression (e) is used for the negative lens disposed in the first group A portion, when the number of positive lenses formed of a low dispersion material having a small refractive index increases, There is a problem that the curvature becomes large and the zoom lens becomes large.

  Therefore, if the zoom lens is configured so as to satisfy the conditional expression (h), occurrence of such a problem can be suppressed.

Sectional drawing which shows schematic structure of the imaging device provided with the zoom lens by embodiment of this invention The figure which compares and shows each state when the zoom lens of an imaging device is set to a wide-angle end and a telephoto end Sectional drawing which shows schematic structure of the zoom lens of Example 1. FIG. The figure which compares and shows each state when the zoom lens of Example 1 is set to the wide-angle end and the telephoto end. Sectional drawing which shows schematic structure of the zoom lens of Example 2. FIG. The figure which compares and shows each state when the zoom lens of Example 2 is set to the wide-angle end and the telephoto end. Sectional drawing which shows schematic structure of the zoom lens of Example 3. The figure which compares and shows each state when the zoom lens of Example 3 is set to the wide-angle end and the telephoto end. Sectional drawing which shows schematic structure of the zoom lens of Example 4. The figure which compares and shows each state when the zoom lens of Example 4 is set to the wide-angle end and the telephoto end. Sectional drawing which shows schematic structure of the zoom lens of Example 5. The figure which compares and shows each state when the zoom lens of Example 5 is set to the wide-angle end and the telephoto end. Sectional drawing which shows schematic structure of zoom lens of Example 6. The figure which compares and shows each state when the zoom lens of Example 6 is set to the wide-angle end and the telephoto end. Sectional drawing which shows schematic structure of the zoom lens of Example 7. The figure which compares and shows each state when the zoom lens of Example 7 is set to the wide-angle end and the telephoto end. Sectional drawing which shows schematic structure of zoom lens of Example 8. The figure which compares and shows each state when the zoom lens of Example 8 is set to the wide-angle end and the telephoto end. Sectional drawing which shows schematic structure of zoom lens of Example 9. The figure which compares and shows each state when the zoom lens of Example 9 is set to the wide-angle end and the telephoto end Sectional drawing which shows schematic structure of the zoom lens of Example 10. The figure which compared each state when the zoom lens of Example 10 is set to the wide-angle end and the telephoto end Sectional drawing which shows schematic structure of the zoom lens of Example 11. The figure which compared each state when the zoom lens of Example 11 is set to the wide-angle end and the telephoto end Sectional drawing which shows schematic structure of the zoom lens of Example 12. The figure which compared each state when the zoom lens of Example 12 is set to the wide-angle end and the telephoto end Sectional drawing which shows schematic structure of the zoom lens of Example 13. The figure which compared each state when the zoom lens of Example 13 is set to the wide-angle end and the telephoto end Sectional drawing which shows schematic structure of zoom lens of Example 14. The figure which compared each state when the zoom lens of Example 14 is set to the wide-angle end and the telephoto end FIG. 6 is a diagram illustrating various aberrations of the zoom lens of Example 1. 6 is a diagram illustrating various aberrations of the zoom lens of Example 2. FIG. 6 is a diagram illustrating various aberrations of the zoom lens of Example 3. FIG. FIG. 6 is a diagram illustrating various aberrations of the zoom lens of Example 4. FIG. 6 is a diagram illustrating various aberrations of the zoom lens of Example 5. FIG. 10 is a diagram illustrating various aberrations of the zoom lens of Example 6. FIG. 10 shows various aberrations of the zoom lens of Example 7. FIG. 10 shows various aberrations of the zoom lens of Example 8. FIG. 10 shows various aberrations of the zoom lens of Example 9. FIG. 10 shows various aberrations of the zoom lens of Example 10. FIG. 10 shows various aberrations of the zoom lens of Example 11. FIG. 14 shows various aberrations of the zoom lens of Example 12. FIG. 14 shows various aberrations of the zoom lens of Example 13. FIG. 18 shows various aberrations of the zoom lens of Example 14. The figure which shows the video camera comprised using the zoom lens of this invention

  Hereinafter, a zoom lens of the present invention and an image pickup apparatus including the zoom lens will be described with reference to the drawings.

  1A and 1B are cross-sectional views illustrating a schematic configuration of an imaging apparatus including a zoom lens according to the present invention. FIG. 1A is a diagram illustrating in detail a state when the zoom setting is set at a wide-angle end, and FIG. It is a figure which compares and shows each state when setting is set to the wide-angle end and the telephoto end. The figure indicated by (W) in FIG. 1B shows a state when the zoom setting is set at the wide-angle end, and the figure indicated by (T) in FIG. 1B shows a state when the zoom setting is set at the telephoto end. Yes.

  The illustrated image pickup apparatus 200 is a consumer video camera apparatus equipped with a small zoom lens 100 having a wide angle and high zoom ratio.

  The zoom lens 100 forms an optical image Hk representing the subject H on a light receiving surface 210J of an image sensor 210 made of a CCD, a CMOS, or the like. The zoom lens 100 with a wide angle and high zoom ratio is a device in which the size of the apparatus is reduced by suppressing the occurrence of chromatic aberration.

  The image pickup device 210 disposed in the image pickup apparatus 200 converts an optical image Hk representing the subject H imaged through the zoom lens 100 into an electrical signal, and outputs an image signal Pk indicating the optical image Hk. is there.

  The zoom lens 100 is assumed to control the opening diameter from when the zoom setting is determined at the telephoto end to when the zoom setting is determined at an intermediate region between the telephoto end and the wide-angle end.

  First, the basic configuration of the zoom lens will be described.

<Basic configuration of zoom lens and its function and effect>
The zoom lens 100 includes, in order from the object side along the optical axis Z1, a positive first lens group G1 that is fixed with respect to the optical axis Z1 direction during zooming, and a negative lens that moves monotonously in the optical axis Z1 direction during zooming. A second lens group G2 having a refractive power of 1, a subsequent lens group Ge having a positive refractive power as a whole, and optical members Cg1 and Cg2 which are color separation optical systems and various filters.

  The second lens group G2 that moves monotonously in the direction of the optical axis Z1 during zooming is moved only in one direction when the magnification is increased during zooming, and is opposite to this one direction when the magnification is decreased during zooming. It is configured to move only in the opposite direction.

  The first lens group G1 includes a first lens group first lens unit G11 composed of two or less lenses (here, one of the negative lenses L1) having negative refractive power, and a convex surface on the image side. A first lens group second lens unit G12 in which only two lenses, a positive lens L2 directed toward the object side and a negative meniscus lens L3 having a concave surface directed toward the object side, are arranged in this order from the object side, and one negative lens (here In this case, the negative lens L4) and at least two positive lenses (here, two lenses, a positive lens L5 and a positive lens L6) are arranged in this order from the object side in the order of the third lens unit G13. is doing.

  The first lens group G1 includes one negative lens (here, a negative lens L4), two to three positive lenses (here, two lenses, a positive lens L5 and a positive lens L6) as an object. A first group A part G1m continuously arranged in this order from the side, and a first group B part G1k arranged on the object side of the first group A part G1m, and conditional expression (e): 27 <νd1mn < 45, conditional expression (f): 2.3 <| f1mn | / f1m <4.5, conditional expression (g): 1.8 <f1m / (fw × ft) 1/2 <3.1, and conditional expression (H): All of 55 <νd1m + <75 are satisfied.

  Here, νd1mn is the Abbe number based on the d-line of the optical member forming one negative lens disposed in the first group A portion G1m, and f1mn is one sheet disposed in the first group A portion G1m. The focal length of the negative lens, f1m is the focal length of the entire first group A section G1m, fw is the focal length of the entire zoom lens system when the zoom setting is set at the wide angle end, and ft is when the zoom setting is set at the telephoto end The focal length of the entire zoom lens system, νd1m +, is an average value with respect to the Abbe number with respect to the d-line of the optical member forming each positive lens arranged in the first group A portion G1m. For example, there are only three positive lenses from the first positive lens to the third positive lens in the first group A section, and the Abbe number of the first positive lens in the first group A section is ν1, the second When the Abbe number of the positive lens is ν2 and the Abbe number of the third positive lens is ν3, the value of νd1m + can be obtained by the equation (νd1m +) = (ν1 + ν2 + ν3) / 3.

  As shown in the figure, the first group B portion G1k corresponds to the first group first lens portion G11 and the first group second lens portion G12, and the first group A portion G1m is the first group. This corresponds to the third lens unit G13.

  Hereinafter, the first lens group G1 having a configuration corresponding to the first group first lens unit G11 to the first group third lens unit G13 is referred to as a zoom lens according to the first embodiment. The first lens group G1 having a configuration corresponding to the first group A portion G1m is referred to as a zoom lens according to the second embodiment.

  Note that the zoom lens according to the second embodiment does not necessarily include the first group B unit G1k.

<Configuration for further limiting the basic configuration of the zoom lens according to the first embodiment>
Next, components that further limit the basic configuration in the first embodiment included in the illustrated zoom lens 100 and the imaging apparatus 200, and the functions and effects thereof will be described. Note that these components that further limit the basic configuration are not essential components for the zoom lens 100 and the imaging apparatus 200 according to the first embodiment of the present invention.

  In addition, the zoom lens 100 and the imaging device 200 according to the first embodiment of the present invention may satisfy only one of the constituent elements that further limit the basic configuration of the first embodiment. A combination of two or more may be satisfied.

  First, the meaning of each parameter indicated by a symbol in the conditional expression is summarized below. Conditional expression (d) is a conditional expression on the assumption that the first lens unit first lens portion is composed of one negative lens.

νd12n: Abbe number based on the d-line of the optical member forming the negative meniscus lens constituting the first lens group second lens portion R12f: Object side lens of the negative meniscus lens constituting the first lens group second lens portion Radius of curvature of surface R12r: radius of curvature of image side lens surface of negative meniscus lens constituting first lens group second lens portion f1: focal length of first lens group fw: zoom when zoom setting is set at wide angle end Focal length of the entire lens system ft: Focal length of the entire zoom lens system when the zoom setting is set at the telephoto end νd13n: d line of the optical member forming the negative lens arranged in the third lens unit of the first group as a reference Abbe number d1: Distance between the most image side lens surface constituting the first lens unit first lens part and the most object side lens surface constituting the first group second lens part (air spacing)
dL: Distance between the most object side lens surface constituting the first lens unit first lens part and the most image side lens surface constituting the first group second lens part f3: Focal length of the entire third lens group f4: Focal length of entire fourth lens group ◇ Limited configuration corresponding to conditional expression (a) Conditional expression (a) limiting the configuration of the zoom lens of the first embodiment: 30 <νd12n <55, and a more desirable conditional expression (A ′): 35 <νd12n <57 defines the Abbe number νd12n with reference to the d-line of the optical member used for the negative meniscus lens L3 constituting the first lens unit second lens portion G12.

  If the zoom lens 100 is configured so as to fall below the lower limit of the conditional expression (a), it is advantageous for reducing the curvature of both the concave and convex lens surfaces of the negative meniscus lens L3 to reduce the thickness of the lens. There arises a problem that it becomes difficult to correct the secondary spectrum.

  Contrary to this, if the zoom lens 100 is configured so as to exceed the upper limit of the conditional expression (a), it is advantageous for correcting the secondary spectrum of chromatic aberration, but the axial chromatic aberration of each wavelength is corrected in a balanced manner. It becomes difficult to do. Along with this, the curvature of the lens for correcting chromatic aberration arranged in the first lens group G1 increases. In particular, in the positive lens in the first lens group G1, the center thickness for securing the necessary edge (edge) is increased, and the overall thickness of the first lens group G1 and the outer diameter are increased. The problem of becoming.

  Therefore, if the zoom lens 100 is configured to satisfy the conditional expression (a) or the conditional expression (a ′), the occurrence of such a problem can be suppressed. If the zoom lens 100 is configured to satisfy the conditional expression (a ′), more desirable lens characteristics can be obtained than when the conditional expression (a) is satisfied.

◇ Limited configuration regarding conditional expression (b) Conditional expression (b) limiting the configuration of the zoom lens according to the first embodiment: −5.0 <(R12f + R12r) / (R12f−R12r) <− 1.0, and More desirable conditional expression (b ′): −4.5 <(R12f + R12r) / (R12f−R12r) <− 1.3 defines the shape factor of the negative meniscus lens disposed in the first lens unit second lens portion G12. To do.

  If the zoom lens 100 is configured so as to fall below the lower limit of the conditional expression (b), the contribution to the chromatic aberration correction of the meniscus lens L3 having negative refractive power constituting the first lens unit second lens portion G12 is reduced, and in particular, zooming is performed. There is a problem in that the generation of axial chromatic aberration becomes too large when the setting is set near the telephoto end.

  On the contrary, if the zoom lens 100 is configured to exceed the upper limit of the conditional expression (b), the chromatic aberration can be corrected, but there is a problem that the first lens group G1 becomes large. .

  Therefore, if the zoom lens 100 is configured to satisfy the conditional expression (b) or the conditional expression (b ′), the occurrence of such a problem can be suppressed. If the zoom lens 100 is configured to satisfy the conditional expression (b ′), more desirable lens characteristics can be obtained than when the conditional expression (b) is satisfied.

◇ Limited configuration related to conditional expression (c) Conditional expression (c) limiting the configuration of the zoom lens of the first embodiment: 22 <νd13n <38, and more desirable conditional expression (c ′): 23 <νd13n <32 Defines the Abbe number νd13n with reference to the d-line of the optical member used for the negative lens L4 disposed in the first lens unit third lens portion G13.

  If the zoom lens 100 is configured to fall below the lower limit of the conditional expression (c), the curvature of the negative lens L4 can be reduced and the first lens group G1 can be reduced in size, but over the entire zoom setting region, It becomes difficult to correct axial chromatic aberration in each wavelength range in a balanced manner.

  On the other hand, if the zoom lens 100 is configured to exceed the upper limit of the conditional expression (c), the curvature of the negative lens L4 must be increased, and the first lens group G1 is increased in size. Problems arise.

  Therefore, if the zoom lens 100 is configured to satisfy the conditional expression (c) or the conditional expression (c ′), the occurrence of such a problem can be suppressed. If the zoom lens 100 is configured to satisfy the conditional expression (c ′), more desirable lens characteristics can be obtained than when the conditional expression (c) is satisfied.

◇ Limited configuration relating to the first lens unit second lens unit The positive lens L2 and the negative meniscus lens L3 configuring the first lens unit second lens unit G12 are cemented, and the first lens unit third lens unit G13 is configured. If the negative lens L4 and the positive lens L5 disposed adjacent to the negative lens L4 are cemented, a configuration advantageous for achromaticity, that is, a configuration capable of satisfactorily correcting chromatic aberration. Therefore, the occurrence of chromatic aberration can be suppressed. Furthermore, since the number of lenses that require a holding mechanism can be reduced by using a cemented lens, the holding member that holds the first lens group G1 can be simplified, and the assembly accuracy can be increased.

◇ Limited configuration regarding conditional expression (d) Conditional expression (d) for limiting the configuration of the zoom lens according to the first embodiment: 0.15 <d1 / dL <0.55, and a more desirable conditional expression (d ′) : 0.18 <d1 / dL <0.52 is a conditional expression on the assumption that the first lens unit first lens portion G11 is composed of one negative lens. That is, the first d with respect to the distance dL (distance dL) on the optical axis from the most object side lens surface of the first group first lens unit G11 to the most image side lens surface of the first group second lens unit G12. Defines the ratio of the distance d1 (air interval d1) on the optical axis Z1 from the most image side lens surface of the first group lens unit G11 to the most object side lens surface of the first group second lens unit G12. It is.

  As shown in FIG. 1A, the most object side lens surface of the first lens unit first lens portion G11 is the object side lens surface of the negative lens L1. The most image side lens surface of the first lens unit second lens portion G12 is the image side lens surface of the negative meniscus lens L3. The most image side lens surface of the first lens unit first lens portion G11 is the image side lens surface of the negative lens L1. Further, the most object side lens surface in the first lens unit second lens portion G12 is the object side lens surface of the positive lens L2.

  If the zoom lens 100 is configured to fall below the lower limit of the conditional expression (d), it becomes necessary to reduce the curvature of the negative lens L1 disposed in the first lens unit first lens portion G11, which is disadvantageous for widening the angle. . If an attempt is made to widen the angle forcibly, there arises a problem that it becomes extremely difficult to correct the aberration of the off-axis light beam at the wide angle end.

  On the contrary, if the zoom lens 100 is configured so as to exceed the upper limit of the conditional expression (d), the thickness of the first lens group first lens portion G11 is increased, the outer diameter is increased, and the entire zoom lens is increased. There arises a problem that the size of the device increases.

  Therefore, if the zoom lens 100 is configured to satisfy the conditional expression (d) or the conditional expression (d ′), the occurrence of such a problem can be suppressed. If the zoom lens 100 is configured so as to satisfy the conditional expression (d ′), more desirable lens characteristics can be obtained than when the conditional expression (d) is satisfied.

◇ Limited configuration relating to the first lens unit first lens unit The first lens unit first lens unit G11 may be configured by only one negative lens L1.

<Configuration for further limiting the basic configuration of the zoom lens according to the second embodiment>
Next, components that further limit the basic configuration of the second embodiment included in the illustrated zoom lens 100 and imaging device 200, and the operation and effect thereof will be described. Note that these components that further limit the basic configuration are not essential components for the zoom lens 100 and the imaging apparatus 200 according to the second embodiment of the present invention.

  In addition, the zoom lens 100 and the imaging device 200 according to the second embodiment of the present invention may satisfy only one of the constituent elements that further limit the basic configuration of the second embodiment. A combination of two or more may be satisfied.

  First, the meanings of the parameters indicated by symbols in conditional expressions other than the conditional expressions already described are summarized below.

νd1mp: Abbe number based on the d-line of the optical member forming the positive lens adjacent to the negative lens arranged in the first group A portion G1m νd1kn: Negative arranged on the most object side of the first group B portion G1k Abbe number based on d-line of optical member forming lens νd1kp: Abbe number based on d-line of optical member forming any positive lens arranged in first group B portion G1k e) to (h) limited configuration The first group A part G1m has conditional expression (e ′): 27 <νd1mn <43, conditional expression (f ′): 2.3 <| f1mn | / f1m <4.3. Conditional Expression (g ′): 2.0 <f1m / (fw × ft) ^1/2 <3.0, Conditional Expression (h ′): 56 <νd1m + <72 Desirably, if so, the above conditional expressions (e) to (h) are satisfied It is possible to obtain the more desirable effects remote.

◇ Limited configuration regarding conditional expression (i) Conditional expression (i) that limits the configuration of the zoom lens according to the second embodiment: 55 <νd1mp <70, and more desirable conditional expression (i ′): 57 <νd1mp <70 This defines the Abbe number of the positive lens L5 adjacent to the negative lens L4 disposed in the first group A portion G1m.

  If the zoom lens 100 is configured to fall below the lower limit of the conditional expression (i), it is difficult to correct axial chromatic aberration well when the zoom setting is set to the telephoto side.

  On the contrary, when the zoom lens 100 is configured to exceed the upper limit of the conditional expression (i), the low dispersion material having such an Abbe number generally has a low refractive index, and constitutes the positive lens L5. Attempting to secure a necessary edge sometimes causes a problem that the center thickness of the positive lens L5 increases. In particular, since the Abbe number optical member represented by the conditional expression (e) is used for the negative lens L4 of the first group A portion G1m, the curvature of the positive lens L5 tends to increase.

  Therefore, if the zoom lens 100 is configured to satisfy the conditional expression (i) or the conditional expression (i ′), the occurrence of such a problem can be suppressed. If the zoom lens 100 is configured to satisfy the conditional expression (i ′), more desirable lens characteristics can be obtained than when the zoom lens 100 satisfies the conditional expression (i).

◇ Limited configuration regarding conditional expression (j) Conditional expression (j) that limits the configuration of the zoom lens according to the second embodiment: 35 <νd1kn <55, and more desirable conditional expression (j ′): 37 <νd1kn <55 The Abbe number νd1kn is defined based on the d-line of the optical member forming the negative lens L1, which is the lens disposed closest to the object side of the first group B portion G1k. The first group B part G1k is disposed on the object side of the first group A part G1m, and includes one or more negative lenses L1 and L3 and one or more positive lenses. It has a lens L2 and belongs to the first lens group G1.

  When increasing the angle of view when the zoom setting is set at the wide-angle end, the angle may be widened with the configuration as in the first group A portion G1m, but in that case, the outer diameter becomes very large and aberrations are increased. Correction becomes very difficult.

  Therefore, the first group B portion G1k, which is a lens portion having a function like a wide conversion lens, is arranged on the object side of the first group A portion G1m, and the first group B portion G1k is taken into the first lens group G1. By (integrating) and optimizing, it is possible to configure a zoom lens that can favorably correct the occurrence of aberrations when the zoom setting is set at the wide-angle end without increasing the outer diameter.

  Since the zoom lens 100 is configured by optimizing the first lens group G1 in this way, the zoom lens in which the first group B portion G1k is separated from the first lens group G1 has an effect as a normal zoom lens. It is not possible. That is, the zoom lens in which the first lens group is configured only by the first group A portion G1m cannot exhibit the function as a normal zoom lens.

  If the zoom lens 100 is configured to exceed the upper limit and lower limit of the conditional expression (j), the lateral chromatic aberration when the zoom setting is set near the wide-angle end, the axial chromatic aberration when the zoom setting is set near the telephoto end, and There arises a problem that it becomes difficult to correct lateral chromatic aberration.

  Therefore, if the zoom lens 100 is configured to satisfy the conditional expression (j) or the conditional expression (j ′), the occurrence of such a problem can be suppressed. If the zoom lens 100 is configured to satisfy the conditional expression (j ′), more desirable lens characteristics can be obtained than when the conditional expression (j) is satisfied.

◇ Limited configuration regarding conditional expression (k) Conditional expression (k) for limiting the configuration of the zoom lens according to the second embodiment: νd1kp> 60 and more desirable conditional expression (k ′): νd1kp> 62 are the first group It defines the Abbe number of one of the positive lenses (here, the positive lens L2) disposed in the B part G1k.

  If the zoom lens 100 is configured to be below the lower limit of the conditional expression (k), it is difficult to correct axial chromatic aberration well.

  Therefore, if the zoom lens 100 is configured to satisfy the conditional expression (k) or the conditional expression (k ′), the occurrence of such a problem can be suppressed. If the zoom lens 100 is configured to satisfy the conditional expression (k ′), more desirable lens characteristics can be obtained than when the conditional expression (k) is satisfied.

If the first group B portion G1k includes a negative meniscus lens L3 having a concave surface facing the object side, the chromatic aberration generated in the first group B portion G1k Since it can be canceled by the chromatic aberration generated in the group A part G1m, off-axis aberrations, in particular, lateral chromatic aberration can be corrected well.

<Common configuration for further limiting the basic configuration of the zoom lenses of the first and second embodiments>
◇ Limited configuration related to conditional expression (m) Conditional formula (m) limiting the configuration of the zoom lens of the first and second embodiments: 1.9 <f1 / (fw × ft) 1/2 <3.1, Further, the more desirable conditional expression (m ′): 2.0 <f1 / (fw × ft) 1/2 <3.0 satisfies the focal length f1 of the first lens group G1 and the entire zoom lens system at the wide angle end. It defines the relationship between the focal length fw and the focal length ft of the entire zoom lens system at the telephoto end.

  If the zoom lens 100 is configured to fall below the lower limit of the conditional expression (m), the power of the first lens group G1 becomes too strong, which occurs when various aberrations are corrected, particularly when the zoom setting is set near the telephoto end. It becomes difficult to correct spherical aberration and coma.

  On the other hand, if the zoom lens 100 is configured to exceed the upper limit of the conditional expression (m), there arises a problem that the lens system becomes too large.

  Therefore, if the zoom lens 100 is configured to satisfy the conditional expression (m) or the conditional expression (m ′), the occurrence of such a problem can be suppressed. If the zoom lens 100 is configured so as to satisfy the conditional expression (m ′), more desirable lens characteristics can be obtained than when the conditional expression (m) is satisfied.

◇ Limited Configuration Related to Subsequent Lens Group The subsequent lens group Ge of the zoom lens according to the first and second embodiments has, in order from the object side, an aperture stop St and a third lens having a positive refractive power fixed at the time of zooming. It can be composed of a lens group G3 and a fourth lens group G4 having a positive refractive power for correcting and focusing a change in image plane position due to zooming. Note that the subsequent lens group Ge is not limited to the above-described aperture stop St, the third lens group G3, and the fourth lens group G4, but may include additional lens groups. Good.

◇ Limited configuration regarding conditional expression (n) Conditional expression (n) that limits the configuration of the zoom lens according to the first and second embodiments: 2.5 <f3 / f4 <5.0, and a more desirable conditional expression ( n ′): 2.6 <f3 / f4 <4.8 defines the ratio of the focal length f3 of the third lens group G3 to the focal length f4 of the fourth lens group.

  If the zoom lens 100 is configured to satisfy the conditional expression (n) or the conditional expression (n ′), a long back focus can be secured while suppressing an increase in size. That is, for example, in a high-quality video camera, a surveillance camera, a TV conference system camera, etc., a three-plate system provided with a color separation optical system is adopted, and such a color separation optical system or ND filter is used. Further, it is possible to ensure a long back focus that can insert an ON / OF mechanism of IR light.

  However, if the zoom lens 100 is configured to fall below the lower limit of the conditional expression (n), it is difficult to ensure a sufficient back focus length.

  Conversely, if the zoom lens 100 is configured so as to exceed the upper limit of the conditional expression (n), the power of the third lens group G3 becomes too weak, the overall length of the zoom lens becomes long, and various aberrations such as spherical aberration can occur. There arises a problem that it becomes difficult to correct aberrations.

  If the zoom lens 100 is configured to satisfy the conditional expression (n ′), more desirable lens characteristics can be obtained than when the conditional expression (n) is satisfied.

<Specific Examples>
2A, 2B,... 15A, 15B and Tables 1 to 15 will be described together with numerical data and the like of each of Examples 1 to 14 of the zoom lens of the present invention. 2A, 2B,..., 15A, 15B, which correspond to the reference numerals in FIG. 1 showing the zoom lens 100 described above, indicate configurations corresponding to each other.

  Of Examples 1 to 14, Examples corresponding to the zoom lens of the first embodiment are Examples 1 to 11 and Example 14.

  Examples corresponding to the zoom lens of the second embodiment are Example 2, Example 4, and Examples 8-14.

  Therefore, Examples corresponding to both the zoom lens of the first embodiment and the zoom lens of the second embodiment are Example 2, Example 4, Examples 8 to 11, and Example 14.

  2A, 2B,... 15A, 15B are cross-sectional views showing the schematic configuration of each of the zoom lenses of Examples 1-14.

  2A, 3A,... 15A are diagrams showing in detail the state where the zoom setting is set at the telephoto end, and FIGS. 2B, 3B,... 15B show the state where the zoom setting is set at the wide angle end and the state where the zoom setting is set at the telephoto end. It is a figure shown in comparison. FIGS. 2B to 15B show the state where the zoom setting is set to the wide angle end, and FIGS. 2B to 15B show the state where the zoom setting is set to the telephoto end. Show.

  2A, 3A,... 15A are symbols indicating the lenses, and correspond to the order of the lenses arranged in order from the object side.

  Tables 1 to 15 are diagrams showing basic data of the zoom lenses of Examples 1 to 7, respectively. Lens data is shown in the upper part (indicated by symbol (a) in the figure) in each table of Tables 1 to 15, and schematic specifications of the zoom lens are shown in the lower part (indicated by symbol (b) in the figure).

  It should be noted that all lens surfaces constituting the zoom lens in these embodiments are spherical or flat.

  Further, Table 15 relates to the zoom lenses of Examples 1 to 14 and is calculated by the calculation formulas in the inequality formulas determined for each embodiment (ranges determined by the inequality formulas (a) to (n)). Or a value corresponding to a constant of the zoom lens optical system indicated by a symbol in the inequality).

  These zoom lenses are controlled so as to restrict the aperture diameter of the aperture stop from when the zoom setting is set at the telephoto end to when the zoom setting is set at an intermediate region between the telephoto end and the wide-angle end. Assume that you will. This open diameter is controlled to be about F2.9 at the telephoto end.

  In each lens data at the top of Tables 1 to 14, the surface number Si is the number of the i-th (i = 1, 2, 3,...) Lens surface or the like that increases sequentially from the most object side to the image side. Indicates. These lens data include the aperture stop St.

  The radius of curvature Ri indicates the radius of curvature of the i-th (i = 1, 2, 3,...) Surface, and the surface interval Di (i = 1, 2, 3,...) Is the i-th surface and i + 1. The surface spacing on the optical axis Z1 with the second surface is shown. The symbol Ri and the symbol Di of the lens data correspond to the symbol Si (i = 1, 2, 3,...) Indicating the lens surface or the like.

  It should be noted that there are cases where a number indicating the surface interval is described in the column of the surface interval Di (i = 1, 2, 3,...) And a code Dn (n is a numerical value). However, the portion where the symbol Dn is described corresponds to the surface interval (air interval) between the lens groups, and the surface interval (air interval) changes as the zoom magnification changes.

  Ndj represents the refractive index with respect to the wavelength of 587.6 nm (d line) for the j-th (j = 1, 2, 3,...) Optical element that sequentially increases from the object side to the image side, and νdj represents the jth. The Abbe number based on the d-line of the optical element is shown.

  In the lens data in Tables 1 to 14, the unit of curvature radius and surface interval is mm, and the curvature radius is positive when convex on the object side and negative when convex on the image side.

  Further, in the column indicated by reference numeral (b) at the bottom of Tables 1 to 14, each value at the wide-angle end and the telephoto end, that is, f: focal length (unit: mm) of the entire lens system, Fno: F number, 2ω: Full angle of view, D10, D17, D24, D31, etc .: Indicates the distance between each lens group.

  Tables 1 to 15 are collectively shown at the end of the description in the “Mode for Carrying Out the Invention”.

  FIGS. 16 to 29 are graphs showing various aberrations of the zoom lenses of Examples 1 to 14. FIGS. In the figure, aberrations relating to light having a wavelength of 587.6 nm, a wavelength of 460.0 nm, and a wavelength of 615.0 nm are shown.

  The aberration diagrams corresponding to the reference numerals (A) to (D) shown in FIGS. 16 to 29 are those at the wide-angle end, and are spherical aberration (A), astigmatism (B), distortion (distortion). Aberration) (C) and chromatic aberration of magnification (chromatic aberration of magnification) (D) are shown. In addition, each aberration diagram corresponding to the reference numerals (E) to (H) shown in each figure is at the telephoto end, and includes spherical aberration (E), astigmatism (F), distortion (distortion aberration) (G). , Chromatic aberration of magnification (chromatic aberration of magnification) (H) is shown.

  The distortion diagram shows the amount of deviation from the ideal image height f × tan θ using the focal length f and half angle of view θ (variable treatment, 0 ≦ θ ≦ ω) of the entire lens system.

  As can be seen from the numerical data and aberration diagrams of Examples 1 to 14, the wide-angle high zoom ratio zoom lens of the present invention can suppress the occurrence of various aberrations and reduce the size of the apparatus.

  FIG. 30 shows a configuration diagram of a video camera which is an example of an imaging apparatus configured using the zoom lens of the present invention. In FIG. 30, the first lens group G1, the second lens group G2, the aperture stop St, the third lens group G3, and the fourth lens group G4 included in the zoom lens 1 are schematically shown.

  The illustrated video camera 10 is a so-called 3CCD image pickup device having three image pickup devices. However, the image pickup device of the present invention is not limited to this, and a single image pickup device may pick up the entire wavelength band. The video camera 10 includes a zoom lens 1, a filter 2 having functions such as a low-pass filter and an infrared cut filter disposed on the image side of the zoom lens 1, and color separation prisms 3R and 3G disposed on the image side of the filter 2. 3B, imaging elements 4R, 4G, and 4B provided on the end faces of the color separation prisms, and a signal processing circuit 5. The image sensors 4R, 4G, and 4B convert an optical image formed by the zoom lens 1 into an electric signal, and for example, a CCD (Charge Coupled Device) can be used. The image pickup devices 4R, 4G, and 4B are arranged so that the image pickup surfaces thereof coincide with the image formation surfaces of the optical images for the respective colors formed through the zoom lens 1.

  Unnecessary light components are removed from the light transmitted through the zoom lens 1 by the filter 2, and then separated into red, green, and blue color lights by the color separation prisms 3R, 3G, and 3B, and imaged by the image sensors 4R, 4G, and 4B. The image is formed on the surface. Output signals from the image pickup devices 4R, 4G, and 4B corresponding to red, green, and blue color lights are arithmetically processed by the signal processing circuit 5 to generate color image signals. The color image signal generated and output by the signal processing circuit 5 is input to the display device 6 and displayed.

In addition, this invention is not limited to said each Example, A various deformation | transformation implementation is possible unless the summary of invention is changed. For example, the radius of curvature, the surface interval, and the refractive index of each lens are not limited to the numerical values shown in the above tables, and may take other values.

G1 1st lens group G2 2nd lens group Ge Subsequent lens group G11 1st group 1st lens part G12 1st group 2nd lens part G13 1st group 3rd lens part

Claims (16)

In order from the object side, a first lens group having a positive refractive power fixed at the time of zooming, a second lens group having a negative refractive power that moves monotonously in the optical axis direction at the time of zooming, and a positive refractive power as a whole A subsequent lens group having
The first lens group, in order from the object side, a first group first lens unit composed of two or less lenses each having a negative refractive power, a lens having a positive refractive power with a convex surface facing the image side, A first group second lens unit in which only two meniscus lenses having a negative refractive power facing the object side and having negative refractive power are arranged in this order from the object side, one negative lens, and at least two positive lenses A zoom lens having a first lens group and a third lens portion that are continuously arranged in this order from the object side. 2. The zoom lens according to claim 1, wherein an Abbe number νd12n with respect to the d-line of the meniscus lens satisfies the following conditional expression (a).
30 <νd12n <55 (a) The zoom lens according to claim 1 or 2, wherein the meniscus lens satisfies the following conditional expression (b).
−5.0 <(R12f + R12r) / (R12f−R12r) <− 1.0 (b)
However,
R12f: radius of curvature of the object side lens surface of the meniscus lens R12r: radius of curvature of the image side lens surface of the meniscus lens The Abbe number νd13n with respect to the d-line of the negative lens disposed in the first lens unit third lens portion satisfies the following conditional expression (c): The zoom lens according to any one of the above.
22 <νd13n <38 (c)   A positive lens that constitutes the first lens unit second lens part and a negative meniscus lens are cemented, and the negative lens that constitutes the first lens group third lens part and adjacent to the negative lens The zoom lens according to any one of claims 1 to 4, wherein the zoom lens is cemented with a positive lens arranged in the same manner. 6. The zoom lens according to claim 5, wherein the following conditional expression (d) is satisfied.
0.15 <d1 / dL <0.55 (d)
However, d1: the distance (air distance) between the most image side lens surface constituting the first lens unit first lens part and the most object side lens surface constituting the first group second lens part
dL: Distance between the most object side lens surface constituting the first lens unit first lens part and the most image side lens surface constituting the first group second lens part   The zoom lens according to any one of claims 1 to 6, wherein the first lens unit first lens unit is configured by a single negative lens. In order from the object side, a first lens group having a positive refractive power fixed at the time of zooming, a second lens group having a negative refractive power that moves monotonously in the optical axis direction at the time of zooming, and a positive refractive power as a whole And a subsequent lens group having
The first lens group includes a first group A portion in which one negative lens, two to three positive lenses are continuously arranged in this order from the object side,
A zoom lens satisfying all of the following conditional expressions (e) to (h):
27 <νd1mn <45 (e)
2.3 <| f1mn | / f1m <4.5 (f)
1.8 <f1m / (fw × ft) ^1/2 <3.1 (g)
55 <νd1m + <75 (h)
However,
νd1mn: Abbe number based on the d-line of one negative lens arranged in the first group A section f1mn: Focal length f1m of one negative lens arranged in the first group A section: first group A The focal length fw of the entire zoom lens system when the zoom setting is set at the wide-angle end ft: The focal length νd1m + of the entire zoom lens system when the zoom setting is set at the telephoto end Average value of Abbe number based on d-line of each positive lens placed in The Abbe number νd1mp based on the d-line of the positive lens adjacent to the negative lens disposed in the first lens unit A satisfies the following conditional expression (i): Item 9. The zoom lens according to Item 8.
55 <νd1mp <70 (i) The first lens group includes a first group B portion having one or more negative lenses and one or more positive lenses on the object side of the first group A portion,
The first lens unit B has the negative lens disposed on the most object side of the first lens unit B. The Abbe number νd1kn with respect to the d-line of the negative lens is expressed by the following conditional expression (j 10. The zoom lens according to claim 8, wherein the zoom lens satisfies the following.
35 <νd1kn <55 (j) 9. The Abbe number νd1kp based on the d-line of any one of the positive lenses arranged in the first group B portion satisfies the following conditional expression (k): The zoom lens according to 10.
60 <νd1kp (k)   The zoom lens according to any one of claims 8 to 11, wherein the first lens unit B includes a negative meniscus lens having a concave surface facing the object side. The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression (m).
1.9 <f1 / (fw × ft) ^1/2 <3.1 (m)
However,
f1: Focal length of the first lens group fw: Focal length of the entire zoom lens system when the zoom setting is set at the wide-angle end ft: Focal length of the entire zoom lens system when the zoom setting is set at the telephoto end   The succeeding lens group is, in order from the object side, a stop, a third lens group having a positive refractive power that is fixed at the time of zooming, and a positive lens that is moved at the time of zooming to correct and focus the position variation of the image plane. The zoom lens according to claim 1, further comprising a fourth lens group having refractive power. The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression (n).
2.5 <f3 / f4 <5.0 (n)
However,
f3: focal length of the third lens group f4: focal length of the fourth lens group   An image pickup apparatus comprising the zoom lens according to claim 1.

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