JPWO2013129274A1 - Converter lens and imaging optical system - Google Patents

Abstract

Provided are a converter lens and an imaging optical system that are sufficiently thin in the thickness direction of the camera while having a zoom ratio of about 3 times. The converter lens CL changes the angular magnification of the converter lens CL by changing the magnification by changing the interval between the built-in lenses. After the image is formed, the light enters the main lens ML. Therefore, the converter lens CL has a reflective optical element for bending the optical path.

Description

  The present invention relates to a converter lens and an image pickup optical system, and in particular, can be mounted in front of a main lens (also referred to as a master lens) provided in advance in an image pickup apparatus or the like, and constitutes an image pickup optical system together with the main lens. The present invention relates to a converter lens and an imaging optical system that can be changed to a shooting field angle different from the shooting field angle.

  For example, a converter lens that can change the focal length of the master lens by attaching it to the camera body so that it is positioned in front of the master lens provided in the camera, and can continuously change the focal length range, It is disclosed in Patent Documents 1 and 2.

JP 2006-106537 A JP 2006-106538 A

  By the way, in recent years, mobile terminals such as smartphones have been released and are rapidly expanding. Such a portable terminal is generally mounted with an imaging device, and is used in various ways such as transferring an image captured by the imaging device or performing image processing on the portable terminal. However, since a general portable terminal is thin, an imaging device incorporated therein is strictly required to be compact. For this reason, since the number of lenses mounted on the imaging device is relatively limited, it is difficult to obtain a high zoom ratio by itself, but there is a desire for some users to take images of distant subjects. For example, there is a request whether a converter lens as shown in Patent Documents 1 and 2 can be attached.

  However, since the converter lens of Patent Documents 1 and 2 has a large overall optical system length and diameter, it is attached so as to protrude toward the subject side of the main lens in the imaging device of the mobile terminal, and thereby handling at the time of shooting. And portability is difficult. It is also desired to change the focal length of the optical system in order to meet the user's desire to obtain a different angle of view and imaging range.

  The present invention has been made in view of the above problems, and an object thereof is to provide a converter lens and an imaging optical system that are sufficiently thin in the thickness direction of the camera while having a zoom ratio of about 3 times.

  The converter lens according to claim 1, wherein the converter lens is disposed closer to the subject side than the main lens and converts the shooting angle of view different from the shooting angle of view of the main lens. The angular magnification of the converter lens is changed by changing the magnification by the above, and the light beam incident on the converter lens is incident on the main lens after primary image formation in the converter lens. The converter lens has a reflective optical element for bending the optical path.

  The converter lens of the present invention can reduce the diameter of the optical system by adopting a so-called Kepler type re-imaging optical system as compared with a Galileo type without primary imaging. Furthermore, by using a bending optical system that bends the optical path with a reflecting optical element such as a prism, the radial direction of the optical system can be matched with the thickness direction of the camera. Therefore, the converter lens is attached in combination with the reduction of the diameter of the converter lens. Since it contributes to thinning of portable terminals and cameras, it is excellent in handling and portability. Further, by changing the distance between the lens groups in the converter, so-called zooming, in which the focal length is continuously changed, becomes possible, so that convenience for the user is enhanced.

  According to a second aspect of the present invention, there is provided a converter lens according to the first aspect of the present invention, in the converter lens according to the first aspect, a meniscus lens having a concave surface facing the subject side in order from the primary imaging point toward the subject side, A lens having a refractive power is arranged.

  By disposing a field lens in the vicinity of the primary imaging point of the converter lens, an image of the exit pupil of the optical system on the subject side from the primary imaging point can be obtained from the optical system on the main lens side from the primary imaging point. If they are formed at the entrance pupil position and are conjugated with each other, the off-axis light beams of the optical system before and after the imaging point can be efficiently transmitted without vignetting. In the case where the lens on the subject side from the primary imaging point is a lens having positive refractive power, the image height of the emitted light beam in the periphery is lowered due to the convergence action, and therefore the object height on the main lens side from the primary imaging point. There is a risk that a difference will occur. Therefore, by arranging a meniscus lens having a concave surface on the subject side closer to the primary imaging point side (main lens side) than the lens having positive refractive power, the image of the optical system on the subject side from the primary imaging point is arranged. The height can be increased, contributing to high-efficiency transmission of off-axis light flux.

  According to a third aspect of the present invention, there is provided a converter lens according to the first aspect, wherein a meniscus lens having a convex surface facing the subject side in order from the primary imaging point toward the subject side, and the subject side in the converter lens. A meniscus lens having a concave surface is disposed, and the combined focal length of the lens disposed on the main lens side from the primary image forming point has a positive value.

  The primary image formation point here refers to that in the axial light beam, but the position of the primary image formation point in the optical axis direction of the axial light beam and the off-axis light beam may be different due to the influence of aberration. According to the third aspect of the present invention, the case where the imaging position of the off-axis light beam is closer to the subject side than the imaging position of the axial light beam is defined. When the refractive power of the optical system on the main lens side has a positive value, the object height of the optical system on the main lens side with respect to the primary imaging point is the image height on the subject side with respect to the primary imaging point. A meniscus lens having a convex surface facing the subject side and a meniscus lens having a concave surface facing the subject side are preferably arranged from the primary imaging point toward the subject side so as not to cause a difference. This enables efficient off-axis light beam transmission without vignetting.

  According to a fourth aspect of the present invention, there is provided a converter lens according to the first aspect of the present invention, wherein in the converter lens, a primary image forming point exists in the lens, and the lens is a meniscus lens having a convex surface facing the subject side. A meniscus lens having a concave surface facing the subject side is disposed on the subject side of the meniscus lens, and the combined focal length of the lens disposed on the main lens side from the primary imaging point has a positive value. And

  Even when the primary image formation point is not in the air such as the lens interval but in the lens, the same effect as in the third aspect is obtained. That is, when the imaging position of the off-axis light beam is closer to the subject than the imaging position of the axial light beam, and the refractive power of the optical system on the main lens side from the primary imaging point has a positive value, The object height of the optical system closer to the main lens than the image formation point does not differ from the image height closer to the object than the primary image formation point. It is preferable to arrange a meniscus lens having a convex surface and a meniscus lens having a concave surface on the subject side. This enables efficient off-axis light beam transmission without vignetting.

According to a fifth aspect of the present invention, the converter lens according to any one of the second to fourth aspects is characterized in that the meniscus lens having a concave surface facing the subject side satisfies the expression (1).
2 <| fMO / fR | <52 (1)
However,
fMO: the focal length of the meniscus lens with the concave surface facing the object side fR: the combined focal length of the lens located on the main lens side from the primary imaging point at the telephoto end of the converter lens

  By exceeding the lower limit of the expression (1), the refractive power of the meniscus lens with the concave surface facing the subject does not become too strong, and astigmatism and distortion occurring in this lens can be kept small. . Also, by falling below the upper limit of the expression (1), the refractive power of the meniscus lens with the concave surface facing the subject does not become too weak, so that the size of the optical system need not be increased.

A converter lens according to a sixth aspect of the present invention is the converter lens according to any one of the second to fourth aspects, wherein the meniscus lens having a concave surface facing the subject side satisfies the expression (2).
−0.5 <SFMO <0.5 (2)
However,
SFMO: A shaping factor of the meniscus lens having a concave surface facing the subject side, which satisfies the following expression.
SFMO = (R1O-R2O) / (R1O + R2O)
Here, R1O is the radius of curvature of the subject side surface of the meniscus lens with the concave surface facing the subject side, and R2O is the radius of curvature of the main lens side surface of the meniscus lens with the concave surface facing the subject side.

  By exceeding the lower limit of the expression (2), the radius of curvature of the subject side surface of the meniscus lens with the concave surface facing the subject side does not become too small, so that distortion aberration, astigmatism, etc. occurring on this surface are suppressed. Is possible. Also, by falling below the upper limit of the expression (2), the radius of curvature of the main lens side surface of the meniscus lens with the concave surface facing the object side does not become too small. Can be suppressed. As a result, it is possible to change the height of the light beam with a short optical path length while suppressing aberration generated on each surface of the lens, which contributes to both ensuring the performance of the optical system and miniaturization.

A converter lens according to a seventh aspect is characterized in that, in the invention according to the third or fourth aspect, the meniscus lens having a convex surface facing the subject side satisfies the expression (3).
4 <| fMT / fR | <10 (3)
However,
fMT: Focal length of the meniscus lens having a convex surface facing the object side fR: Composite focal length of a lens located on the main lens side from the primary imaging point at the telephoto end of the converter lens

  By exceeding the lower limit of the expression (3), the refractive power of the meniscus lens having a convex surface directed toward the subject side does not become too strong, so that distortion aberration, astigmatism, etc. generated in this lens can be suppressed. Further, when the value falls below the upper limit of the expression (3), the refractive power of the meniscus lens having the convex surface directed toward the subject side does not become too weak, so that the optical system does not become too large.

The converter lens according to an eighth aspect of the present invention is the invention according to any one of the third, fourth, and seventh aspects, wherein the meniscus lens having a convex surface facing the subject side satisfies the expression (4).
0 <SFMT <0.3 (4)
However,
SFMT: A shaping factor of the meniscus lens having a convex surface facing the subject side, which satisfies the following expression.
SFMT = (R1T−R2T) / (R1T + R2T)
Where R1T is the radius of curvature of the subject side surface of the meniscus lens with the convex surface facing the subject side, and R2T is the radius of curvature of the main lens side surface of the meniscus lens with the convex surface facing the subject side.

  By exceeding the lower limit of the expression (4), the radius of curvature of the subject side surface of the meniscus lens with the convex surface facing the subject side does not become too small, so that distortion aberration, astigmatism, etc. occurring on this surface are suppressed. Is possible. In addition, since the radius of curvature of the side surface of the main lens of the meniscus lens with the convex surface facing the subject is not reduced too much by falling below the upper limit value of the expression (4), distortion aberration, astigmatism, etc. occurring on this surface Can be suppressed. As a result, it is possible to change the height of the light beam with a short optical path length while suppressing aberration generated on each surface of the lens, which contributes to both ensuring the performance of the optical system and miniaturization.

  According to a ninth aspect of the present invention, there is provided the converter lens according to the first aspect of the present invention, wherein in the converter lens, a primary imaging point exists in the lens, and the lens is formed by a paraxial radius of curvature of a surface on the object side. A meniscus lens having a positive refractive power at the periphery of the lens with a concave surface facing the subject side, and a lens having a negative refractive power disposed on the subject side from the meniscus lens. To do.

  In the converter lens, when the lens closer to the subject than the primary image formation point is a lens having negative refractive power, the peripheral exit light flux has a higher image height due to the divergence action, so that the image height is higher than the primary image formation point. A difference from the object height on the lens side occurs. Therefore, by placing a lens having a positive refractive power on the primary imaging point side (main lens side) of the lens having a negative refractive power, the image height of the optical system on the subject side from the primary imaging point can be increased. This contributes to high-efficiency transmission of off-axis light flux. At this time, if the concave surface of the lens near the optical axis, that is, the paraxial curved surface is directed toward the subject, the distance between the principal points of the lens having negative refractive power and the lens having positive refractive power can be increased. As a result, the refractive power of the lens having the positive refractive power can be reduced while maintaining the combined refractive power of the lens having the negative refractive power and the lens having the positive refractive power. The change in the optical performance due to the manufacturing error can be kept small.

  Note that the paraxial radius of curvature referred to in the present application is the minimum self-measurement of the shape measurement value near the center of the lens (specifically, the central region within 10% of the lens outer diameter) in the actual lens measurement scene. The approximate curvature radius when fitting by multiplication is regarded as the paraxial curvature radius. For example, when a secondary aspherical coefficient is used, a radius of curvature that takes into account a secondary aspherical coefficient in a reference curvature radius of an aspherical definition formula described later is regarded as a paraxial curvature radius (for example, as a reference). (See pages 41 to 42 of “Lens Design Method” by Yoshiya Matsui, Kyoritsu Publishing Co., Ltd.).

  A converter lens according to a tenth aspect is the invention according to any one of the first to ninth aspects, wherein the converter lens is a lens having a positive refractive power and a reflection for bending an optical path in order from the main lens side. It has an optical element.

  When the converter lens is configured in the order of a lens having a positive refractive power and a reflective optical element in order from the main lens side, when the light beam is traced back from the imaging position of the main lens, the axis from the main lens Refraction of the outer light beam by a lens having a positive refractive power can reduce the height of the light beam, and the diameter of the subsequent reflecting optical element can also be suppressed to a small size, which contributes to miniaturization of the optical system. This is particularly effective for reducing the thickness of the camera in the thickness direction.

According to an eleventh aspect of the present invention, in the converter lens according to the tenth aspect, the lens having the positive refractive power satisfies the expression (5).
0.8 <fRP / fR <2.1 (5)
However,
fMR: focal length of the lens having the positive refractive power fR: synthetic focal length of the lens located on the main lens side from the primary imaging point at the telephoto end in the converter lens

  When the value of the expression (5) exceeds the lower limit, the refractive power of a lens having a positive refractive power does not become too strong, so that changes in optical performance due to various aberrations and manufacturing errors generated here can be suppressed to a small value. it can. On the other hand, when the value of the formula (5) is less than the upper limit value, it is possible to secure the refractive power of a lens having a positive refractive power, and it is possible to prevent an increase in the size of the optical system.

  A converter lens according to a twelfth aspect is the optical system according to any one of the first to eleventh aspects, wherein the converter lens is an optical element having a refractive power arranged on the main lens side from a primary imaging point. The number of elements is two or less.

  This simplifies the optical system and contributes to reduction in size and weight.

  A converter lens according to a thirteenth aspect is characterized in that, in the invention according to any one of the first to twelfth aspects, the number of reflections for bending the optical path is two or less.

  When the number of reflections for bending the optical path is set to 2 times or less, it is possible to prevent the structure from becoming complicated, or the change in the optical performance due to the manufacturing error of the reflecting surface becomes remarkable, and the productivity is lowered due to the deterioration of the yield.

  A converter lens according to a fourteenth aspect is the invention according to any one of the first to thirteenth aspects, wherein a focal position shift when the object distance changes is determined by changing a part of the lenses in the converter lens in the optical axis direction. It is characterized by correcting by moving to.

  In the so-called teleconverter, in which the focal length of the entire system becomes long as a result of mounting the converter lens, the focusable subject distance when focusing with only the main lens is extended is possible when the main lens alone is in focus It becomes far away from the distance. However, if focusing is performed by moving the lens in the converter lens, shooting at a closer subject distance is possible, and the shooting range is expanded.

  A converter lens according to a fifteenth aspect is the invention according to any one of the first to fourteenth aspects, wherein the converter lens includes, in order from the subject side, a lens having a negative refractive power and a reflection for bending the optical path. And an optical element.

  If the optical path is bent at a position closest to the subject side surface (first surface) of the converter lens, the thickness direction of the camera to which the converter lens is attached becomes the radial direction of the converter lens. This is advantageous for thinning a camera equipped with a converter lens. In particular, if the first lens is a lens having a negative refractive power and a reflecting optical element for bending the optical path is disposed immediately thereafter, the effective diameter of the reflecting optical element can be kept small by the diverging action of the lens having a negative refractive power. As a result, it contributes to the miniaturization of the optical system, in particular, the thinning.

  A converter lens according to a sixteenth aspect of the present invention is the converter lens according to any one of the first to fifteenth aspects, wherein a lens located on the subject side of the primary imaging point at the telephoto end is the subject of the converter lens Positive first lens group, negative second lens group, positive third lens group, positive fourth lens group, positive fifth lens group, or positive first lens group, negative second The third lens group includes a lens group, a positive third lens group, a positive fourth lens group, and a negative fifth lens group, and zooming is performed by moving the second lens group and the fourth lens group. An aperture stop is disposed on the subject side or the main lens side of the lens group.

  By placing the zooming group on the second lens group and the fourth lens group, the front lens diameter can be kept smaller than when only the second lens group is responsible for zooming, and the optical diameter can be reduced. Contribute. In addition, since the fluctuation of the pupil position is suppressed by fixing the aperture stop, the F number change from the wide-angle end to the telephoto end is small, and a relatively bright optical system can be achieved.

An imaging optical system according to a seventeenth aspect includes the converter lens according to any one of the first to sixteenth aspects and a main lens, and satisfies the expression (6).
1.0 <fR / fM <2.0 (6)
However,
fM: focal length of the main lens fR: composite focal length of the converter lens located on the main lens side from the primary imaging point at the telephoto end of the converter lens

  Since the value of the equation (6) exceeds the lower limit value, the combined focal length of the lens located on the main lens side from the primary imaging point at the telephoto end of the converter lens does not become too small. The F-numbers of the two optical systems sandwiching the primary image forming point are not too bright, and aberration correction is not difficult. On the other hand, it is preferable that the value of the expression (6) is less than the upper limit value because the two optical systems do not need to be enlarged.

An imaging optical system according to an eighteenth aspect includes the converter lens according to any one of the first to sixteenth aspects and a main lens, and satisfies the expression (7).
2.5 <fTOT / fM <4 (7)
However,
fM: focal length of the main lens fTOT: focal length at the telephoto end of the entire system in a state where the converter lens is disposed on the subject side of the main lens

  By exceeding the lower limit value of the expression (7), it is possible to achieve a sufficient telephoto, and it is possible to further enlarge a long-distance object, or to perform portrait photography effectively by greatly blurring the background other than the subject. Moreover, the excessive enlargement of an optical system can be prevented by being less than the upper limit of (7) Formula.

  According to the present invention, it is possible to provide a converter lens and an imaging optical system that are sufficiently thin with respect to the thickness direction of the camera while having a zoom ratio of about 3 times.

It is a perspective view which shows the state which attached the imaging optical system concerning this Embodiment to the portable terminal. 1 is a cross-sectional view of an imaging optical system according to Example 1. FIG. FIG. 4 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the wide-angle end of the imaging optical system in Example 1; FIG. 6 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at an intermediate position of the imaging optical system of Example 1. FIG. 6 is aberration diagrams (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of the imaging optical system of Example 1. 6 is a cross-sectional view of an imaging optical system according to Example 2. FIG. FIG. 6 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the wide-angle end of the imaging optical system in Example 2. FIG. 6 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at an intermediate position in the imaging optical system of Example 2. FIG. 6 is aberration diagrams (spherical aberration (a), astigmatism (b), distortion aberration (c)) at the telephoto end of the imaging optical system of Example 2. 6 is a cross-sectional view of an imaging optical system according to Example 3. FIG. It is sectional drawing of the imaging optical system of Example 3 made into the 2 bending type. It is sectional drawing of the imaging optical system of Example 3 made into 1 bending type. FIG. 10 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the wide-angle end of the imaging optical system in Example 3. FIG. 6 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at an intermediate position in the imaging optical system of Example 3. FIG. 6 is aberration diagrams (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of the imaging optical system of Example 3. 6 is a cross-sectional view of an imaging optical system according to Example 4. FIG. FIG. 10 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the wide-angle end of the imaging optical system in Example 4. FIG. 10 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at an intermediate position in the imaging optical system of Example 4. FIG. 12 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of the imaging optical system in Example 4. 10 is a cross-sectional view of an imaging optical system according to Example 5. FIG. FIG. 10 is aberration diagrams (spherical aberration (a), astigmatism (b), distortion (c)) at the wide-angle end of the imaging optical system in Example 5. FIG. 10 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the intermediate position of the imaging optical system according to Example 5. FIG. 10 is aberration diagrams (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of the imaging optical system of Example 5. 10 is a cross-sectional view of an imaging optical system according to Example 6. FIG. FIG. 12 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the wide-angle end of the imaging optical system in Example 6. FIG. 10 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at an intermediate position in the imaging optical system according to Example 6. FIG. 12 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of the imaging optical system in Example 6. FIG. 10 is a cross-sectional view of an image pickup optical system according to a seventh embodiment. FIG. 12 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the wide-angle end of the imaging optical system in Example 7. FIG. 10A is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at an intermediate position in the imaging optical system according to Example 7. FIG. 10 is aberration diagrams (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of the imaging optical system in Example 7. FIG. 4 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion aberration (c)) of the main lens 1. FIG. 4 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion aberration (c)) of the main lens 2.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a state in which the imaging optical system according to the present embodiment is attached to a portable terminal. For example, the portable terminal SF, which is a thin smartphone, has a built-in imaging device (not shown) including the main lens ML. The main lens ML has its subject side facing the front side (front side in FIG. 1) of the mobile terminal SF.

  The converter lens CL is disposed in an elongated casing BX attached along the rectangular plate body BD of the mobile terminal SF. Note that the housing BX is formed as a separate unit from the body BD, and may be attached to the body BD, or may be a part of the body BD. In this example, the surface closest to the subject of the converter lens CL is exposed from one end of the housing BX toward the subject. On the other hand, the surface of the converter lens CL closest to the main lens faces the main lens ML coaxially. The converter lens CL and the main lens ML constitute an imaging optical system.

  The converter lens CL changes the angular magnification of the converter lens CL by changing the distance between the built-in lenses, and the light beam incident on the converter lens CL is primary in the converter lens CL. After forming an image, the light enters the main lens ML. The converter lens CL has a reflective optical element for bending the optical path. The subject light that has passed through the converter lens CL and the main lens ML is received by an image sensor (not shown) and converted into an electrical signal. The subject can be imaged with only the main lens ML with the converter lens CL removed. However, by attaching the converter lens CL, an imaging optical system capable of zooming can be obtained.

  A monitor (not shown) on the back surface of the portable terminal SF displays an image based on an electrical signal output from the image sensor, functions as an electronic viewfinder, and displays a captured image in almost real time. In this state, zooming, focusing, exposure, and the like are set as needed by driving the converter lens CL and / or the main lens ML based on input from the photographer. The zooming may be performed manually or by actuator driving. Furthermore, when a user performs a release operation at a timing at which still image shooting is desired, a still image is shot. As a result, the image data is recorded in the memory.

  Note that the description in the above embodiment and each example is a preferred example according to the present invention, and the present invention is not limited to this. The imaging optical system can also be mounted on a digital still camera or a video camera.

(Example)
Next, examples suitable for the above-described embodiment will be described. However, the present invention is not limited to the following examples.
Fno: F number ω: Half angle of view (°)
r: radius of curvature (mm)
d: Distance between shaft upper surfaces (mm)
nd: refractive index of lens material with respect to d-line νd: Abbe number of lens material

  In each embodiment, S is a surface number, and the surface on which the aspheric coefficient is described is a surface having an aspheric shape. The aspheric shape has an apex at the surface as an origin and an X axis in the optical axis direction. The height in the direction perpendicular to the optical axis is represented by the following “Equation 1”.

However,
Ai: i-th order aspherical coefficient R: reference radius of curvature K: conic constant Repeatedly, the paraxial radius of curvature referred to in the present application is the vicinity of the center of the lens (specifically, the lens outer diameter) in the actual lens measurement scene. The approximate radius of curvature when the measured shape value in the center region within 10%) is fitted by the least square method is regarded as the paraxial radius of curvature. For example, when a secondary aspherical coefficient is used, a curvature radius that takes into account the secondary aspherical coefficient in the reference curvature radius of the aspherical definition formula is regarded as a paraxial curvature radius.

Example 1
Table 1 shows lens data of Example 1. In the following (including lens data in the table), a power of 10 (for example, 2.5 × 10 ⁻⁰² ) is changed to E (for example, 2.5E-02).
). FIG. 2 is a sectional view of the image pickup optical system according to the first embodiment. In the figure, GR1 is a first lens group having a positive refractive power, and includes a first lens G1 having a negative refractive power, a first prism PR1 which is a reflective optical element, and a second lens G2. GR2 is a second lens group having negative refractive power, and includes a third lens G3, and a fourth lens G4 and a fifth lens G5 which are cemented lenses (G4 / 5). Further, GR3 is a third lens group having a positive refractive power, and includes only the sixth lens G6. GR4 is a fourth lens group having a positive refractive power, and includes a seventh lens G7, an eighth lens G8, and a ninth lens G9 which are cemented lenses (G7 / 8/9). Furthermore, GR5 is a fifth lens group having a positive refractive power, and includes a tenth lens G10 and an eleventh lens G11. GR6 is a sixth lens group having a positive refractive power, and includes a twelfth lens G12, a thirteenth lens G13, a fourteenth lens G14, and a fifteenth lens G15. G is a main lens provided in the imaging apparatus. S denotes an aperture stop provided on the main lens side of the sixth lens G6, and IM denotes an image pickup surface of the image pickup apparatus. CG represents a parallel plate assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state image sensor, or the like. In this embodiment, a mirror MR is inserted as a reflective optical element between the tenth lens group G10 and the eleventh lens group G11, whereby an optical axis two-bending structure can be obtained. The 35th surface is the aperture stop of the main lens.

[Table 1]
Example 1
Unit mm

[Table 1-1] Optical system data (converter lenses: s1 to s34, main lenses: s35 to s48)
srd nd νd
1 64.744 0.50 1.92286 20.9
2 11.863 1.60
3 infinity 9.46 1.90366 31.3
4 infinity 0.40
5 10.000 1.75 1.80139 45.4
6 -47.783 variable
7 16.181 0.40 1.85026 32.3
8 4.138 1.90
9 -14.128 0.47 1.64769 33.8
10 4.962 1.36 1.94595 18.0
11 19.679 variable
12 8.798 1.06 1.66547 55.2
13 300.914 0.70
14 (Aperture) infinity variable
15 12.684 0.52 1.62299 58.1
16 10.825 0.68 1.84666 23.8
17 4.300 2.75 1.69680 55.5
18 -16.871 variable
19 7.041 1.68 1.54400 56.0
20 6.609 0.52
21 infinity 0.70
22 infinity 3.92
23 infinity 1.00
24 infinity 0.68
25 -19.250 1.66 1.94595 18.0
26 -6.822 1.31
27 -4.315 2.06 1.88300 40.8
28 -4.882 0.40
29 2.601 1.68 1.54400 56.0
30 4.543 1.47
31 -1.033 0.55 1.63400 24.0
32 -2.168 0.40
33 1.109 1.29 1.54400 56.0
34 2.100 0.76
35 infinity 0.05
36 infinity -0.21
37 1.699 0.63 1.54400 56.0
38 -12.145 0.05
39 3.731 0.28 1.63400 24.0
40 1.483 0.62
41 111.675 0.29 1.63400 24.0
42 -1000000.000 0.36
43 -6.238 0.84 1.54400 56.0
44 -1.174 0.28
45 -8.341 0.45 1.53 100 56.0
46 1.499 0.64
47 infinity 0.30 1.51633 64.1
48 infinity 0.40
49 (image plane) infinity 0.00


[Table 1-2] Various focal lengths at the wide-angle end, intermediate position, and telephoto end in the combined system of the converter lens and main lens 4.32 7.20 12.34
Fno 3.54 3.87 4.42
ω (degrees) 36.39 22.71 13.45
Total lens length 61.0 61.0 61.0
d6 0.400 3.315 5.709
d11 5.709 2.795 0.400
d14 5.873 3.688 1.400
d18 0.400 2.585 4.873


[Table 1-3] Aspheric coefficient Ai and conic constant K of aspheric lens
5th page
K = 0, A4 = -2.47902E-04, A6 = 6.87846E-06, A8 = -2.38998E-07, A10 = 2.22032E-09, A12 = 0, A14 = 0
6th page
K = 0, A4 = -1.45576E-04, A6 = 1.19528E-05, A8 = -4.74864E-07, A10 = 7.02861E-09, A12 = 0, A14 = 0
12th page
K = 0, A4 = -2.28105E-04, A6 = -1.91373E-05, A8 = 4.39353E-06, A10 = -6.47558E-07, A12 = 0, A14 = 0
19th page
K = 0, A4 = -3.63698E-03, A6 = -1.29964E-04, A8 = 2.64840E-06, A10 = -1.30499E-07, A12 = 0, A14 = 0
20th page
K = 0, A4 = -5.79726E-03, A6 = -1.80186E-04, A8 = 1.88671E-05, A10 = -6.34422E-07, A12 = 0, A14 = 0
29th page
K = -1.864, A4 = 3.02992E-03, A6 = 3.97969E-04, A8 = -5.30371E-05, A10 = 2.58462E-06, A12 = 0, A14 = 0
30th page
K = -6.660, A4 = -1.26827E-02, A6 = 1.00443E-03, A8 = -5.35421E-05, A10 = 3.32439E-06, A12 = 0, A14 = 0
No. 31
K = -3.284, A4 = 6.62847E-03, A6 = -8.47806E-04, A8 = 6.82038E-05, A10 = -2.44694E-06, A12 = 0, A14 = 0
32nd page
K = -6.537, A4 = 8.47741E-03, A6 = -1.09584E-03, A8 = 5.64972E-05, A10 = -1.65491E-06, A12 = 0, A14 = 0
Side 33
K = -2.261, A4 = 5.77486E-02, A6 = -1.16017E-02, A8 = 1.89827E-03, A10 = -1.27673E-03, A12 = 0, A14 = 0
34th page
K = 0.305, A4 = 2.73098E-03, A6 = -1.53945E-02, A8 = -1.00254E-02, A10 = 1.57421E-03, A12 = 0, A14 = 0
37th page
K = 0.045, A4 = 4.09977E-03, A6 = 3.79437E-03, A8 = -5.05465E-03, A10 = 4.24406E-03, A12 = 0, A14 = 0
38th page
K = 18.502, A4 = 2.86613E-02, A6 = 5.80873E-02, A8 = -1.01850E-01, A10 = 4.98182E-02, A12 = 0, A14 = 0
39th page
K = -29.604, A4 = -5.90776E-02, A6 = 1.89791E-01, A8 = -2.57975E-01, A10 = 1.58022E-01, A12 = -3.47186E-02, A14 = 0
40th page
K = -5.422, A4 = 2.16598E-02, A6 = 1.02042E-01, A8 = -9.43786E-02, A10 = 4.93681E-02, A12 = 0, A14 = 0
41st page
K = -30.000, A4 = -1.20105E-01, A6 = -2.57582E-02, A8 = 5.37367E-02, A10 = 2.83845E-02, A12 = -2.20366E-02, A14 = -3.04436E-05
42nd
K = 9.987, A4 = -1.08113E-01, A6 = 1.17911E-02, A8 = 4.21478E-03, A10 = 3.07758E-02, A12 = -1.13692E-02, A14 = -4.66032E-04
No. 43
K = 8.246, A4 = 3.41869E-03, A6 = 2.47140E-02, A8 = -5.38394E-03, A10 = -4.05271E-04, A12 = 1.62304E-04, A14 = 0
44th page
K = -4.235, A4 = -5.01998E-02, A6 = 5.22151E-02, A8 = -1.14003E-02, A10 = 4.64219E-04, A12 = 0, A14 = 0
45th page
K = 5.654, A4 = -3.75710E-02, A6 = 7.50889E-03, A8 = 1.32115E-03, A10 = -2.70599E-04, A12 = -1.16632E-05, A14 = 0
46th page
K = -8.912, A4 = -5.90906E-02, A6 = 1.60085E-02, A8 = -3.52498E-03, A10 = 4.40814E-04, A12 = -2.45474E-05, A14 = 0

[Table 1-4] Specifications (converter lens 1-6 groups and main lens, the same applies below)
First group focal length 13.237
Second group focal length -5.060
3rd group focal length 13.541
4th focal length 13.709
5th group focal length 11.250
6th focal length 4.435
Main lens focal length 4.315
Magnification ratio of converter lens 2.86

  FIG. 3 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion aberration (c)) at the wide-angle end in Example 1. FIG. 4 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion aberration (c)) at an intermediate position in Example 1. FIG. 5 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion aberration (c)) at the telephoto end of Example 1. Here, the aberration diagram is a state in which the converter lens and the main lens are combined, and this embodiment is combined with the main lens having the aberration characteristics shown in FIG. In the spherical aberration diagram, the dotted line represents the amount of spherical aberration with respect to the g line, and the solid line represents the amount of spherical aberration with respect to the d line. In the astigmatism diagram, the solid line S represents the sagittal plane, and the dotted line M represents the meridional plane (the same applies hereinafter).

  In the imaging optical system of Example 1, the second lens group GR2 and the fourth lens group GR4 move along the optical axis direction during zooming from the wide-angle end to the telephoto end, and the distance between the lens groups is changed. Scaling can be performed. More specifically, as it goes from the wide-angle end to the telephoto end, the second lens group GR2 monotonously goes to the main lens side, and the fourth lens group GR4 monotonously goes to the subject side. Further, by moving only the fourth lens group GR4 in the optical axis direction, focusing from infinity to a finite distance (including focal position deviation correction when the object distance changes) can be performed. The primary image formation point position is a position of 0.50 to 0.53 mm from the main lens side surface of the eleventh lens G11 to the main lens side (paraxial value).

(Example 2)
Table 2 shows lens data of Example 2. FIG. 6 is a cross-sectional view of the imaging optical system according to the second embodiment. In the figure, GR1 is a first lens group having a positive refractive power, and includes a first lens G1 having a negative refractive power, a first prism PR1 which is a reflective optical element, and a second lens G2. GR2 is a second lens group having negative refractive power, and includes a third lens G3, and a fourth lens G4 and a fifth lens G5 which are cemented lenses (G4 / 5). Further, GR3 is a third lens group having a positive refractive power, and includes only the sixth lens G6. GR4 is a fourth lens group having a positive refractive power, and includes a seventh lens G7, an eighth lens G8, and a ninth lens G9 which are cemented lenses (G7 / 8/9). Further, GR5 is a fifth lens group having a negative refractive power, and includes only the tenth lens G10. GR6 is a sixth lens group having positive refractive power, and includes an eleventh lens G11, a twelfth lens G12, a second prism PR2 that is a reflective optical element, and a thirteenth lens G13. G is a main lens provided in the imaging apparatus. S denotes an aperture stop provided on the main lens side of the sixth lens G6, and IM denotes an image pickup surface of the image pickup apparatus. Further, F represents a cover glass, and CG represents a parallel flat plate assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state imaging device, and the like. In this embodiment, the optical axis is bent twice. The 33rd surface is the aperture stop of the main lens.

[Table 2]
Example 2
Unit mm

[Table 2-1] Optical system data (converter lenses: s1 to s30, main lenses: s31 to s46)
srd nd νd
1 35.556 0.60 1.90366 31.3
2 10.062 2.63
3 infinity 11.06 1.84666 23.8
4 infinity 0.20
5 11.242 2.94 1.69980 55.2
6 -30.569 variable
7 20.653 0.50 1.94595 18.0
8 5.335 1.95
9 -12.692 1.74 1.65844 50.9
10 7.866 1.54 1.94595 18.0
11 172.878 variable
12 12.907 1.00 1.66547 55.2
13 344.326 0.50
14 (Aperture) infinity variable
15 25.855 1.77 1.61800 63.4
16 -171.908 0.63 1.90366 31.3
17 7.487 2.52 1.69680 55.5
18 -13.526 variable
19 8.072 3.00 1.54400 56.0
20 4.782 5.13
21 -8.146 5.00 1.54400 56.0
22 -2.291 0.20
23 3.981 1.52 1.54400 56.0
24 1.855 1.79
25 infinity 7.79 1.84666 23.8
26 infinity 0.20
27 5.895 1.74 1.54400 56.0
28 -13.926 0.12
29 infinity 0.79 1.51633 64.1
30 infinity 0.64
31 infinity 0.79 1.51633 64.1
32 infinity 1.16
33 infinity 0.05
34 infinity -0.24
35 1.676 0.63 1.54400 56.0
36 -13.857 0.05
37 4.012 0.28 1.63400 24.0
38 1.559 0.57
39 -36.876 0.31 1.63400 24.0
40 -35.075 0.42
41 -6.434 0.86 1.54400 56.0
42 -0.965 0.23
43 -2.637 0.45 1.53 100 56.0
44 1.582 0.65
45 infinity 0.30 1.51633 64.1
46 infinity 0.40
47 (image plane) infinity 0.00


[Table 2-2] Values at the wide-angle end, intermediate position, and telephoto end in the combined system of the converter lens and main lens
Focal length 4.32 7.18 12.30
Fno 3.50 3.91 4.49
ω (degrees) 36.27 22.72 13.44
Total lens length 90.6 90.6 90.6
d6 0.500 4.023 7.027
d11 7.026 3.502 0.500
d14 7.704 4.067 0.500
d18 11.001 14.637 18.206

[Table 2-3] Aspheric coefficient Ai and conic constant K of aspheric lens
5th page
K = 0, A4 = -2.27544E-04, A6 = 2.01478E-06, A8 = -3.92050E-08, A10 = -4.80384E-10, A12 = 0, A14 = 0
6th page
K = 0, A4 = -1.57528E-04, A6 = 5.11676E-06, A8 = -1.24934E-07, A10 = 6.84687E-10, A12 = 0, A14 = 0
12th page
K = 0, A4 = -2.42386E-04, A6 = -1.29609E-05, A8 = 2.84671E-06, A10 = -2.48116E-07, A12 = 0, A14 = 0
Side 13
K = 0, A4 = -8.39279E-05, A6 = -2.44676E-05, A8 = 6.08928E-06, A10 = -5.98503E-07, A12 = 0, A14 = 0
19th page
K = 1.380, A4 = -1.99244E-03, A6 = -3.14904E-05, A8 = -6.48010E-08, A10 = -4.57221E-08, A12 = 0, A14 = 0
20th page
K = -1.819, A4 = -7.98923E-04, A6 = 2.05864E-05, A8 = -3.23864E-06, A10 = 6.48283E-08, A12 = 0, A14 = 0
21st page
K = -14.216, A4 = 2.20016E-03, A6 = -1.47496E-05, A8 = 5.59975E-09, A10 = -2.01980E-09, A12 = 0, A14 = 0
22nd page
K = -3.714, A4 = -1.75225E-03, A6 = 1.04026E-04, A8 = -1.29667E-06, A10 = -5.72403E-10, A12 = 0, A14 = 0
23rd page
K = -1.169, A4 = 2.32097E-03, A6 = 3.05805E-06, A8 = -8.82013E-06, A10 = 7.19682E-08, A12 = 0, A14 = 0
24th page
K = -4.076, A4 = 7.16887E-03, A6 = -6.30067E-04, A8 = 1.30011E-05, A10 = -7.49986E-08, A12 = 0, A14 = 0
27th page
K = -1.460, A4 = 5.33352E-04, A6 = -1.99172E-04, A8 = 3.97077E-05, A10 = -3.34802E-06, A12 = 0, A14 = 0
28th page
K = 12.555, A4 = 1.33749E-03, A6 = 1.45277E-04, A8 = -1.65793E-05, A10 = -1.65037E-08, A12 = 0, A14 = 0
35th page
K = -0.025, A4 = 5.47370E-03, A6 = 1.88020E-03, A8 = -3.19280E-03, A10 = 1.70370E-02, A12 = -2.18680E-02, A14 = 8.42100E-03
36th page
K = -29.823, A4 = 2.98640E-02, A6 = 3.68780E-02, A8 = -4.32080E-02, A10 = -2.39990E-02, A12 = 2.70620E-02, A14 = 0
37th page
K = -30.000, A4 = -4.44840E-02, A6 = 1.45640E-01, A8 = -1.27280E-01, A10 = -3.26040E-02, A12 = 7.77900E-02, A14 = -1.88760E-02
38th page
K = -6.295, A4 = 4.79850E-02, A6 = 5.18720E-02, A8 = -1.88520E-02, A10 = -6.35010E-03, A12 = -4.10750E-03, A14 = 2.20700E-02
39th page
K = 30.000, A4 = -1.22180E-01, A6 = -2.65360E-02, A8 = 6.23540E-02, A10 = 2.03720E-02, A12 = -1.85540E-02, A14 = -6.33860E-04
40th page
K = 30.000, A4 = -1.00270E-01, A6 = 3.06270E-03, A8 = 1.91060E-02, A10 = 1.60540E-02, A12 = -2.27710E-03, A14 = -2.79440E-03
41st page
K = 7.826, A4 = -3.77240E-04, A6 = 2.04210E-02, A8 = -1.10470E-03, A10 = -1.62070E-03, A12 = 2.64450E-04, A14 = 0
42nd
K = -4.059, A4 = -4.31848E-02, A6 = 5.15777E-02, A8 = -1.18416E-02, A10 = 6.53179E-04, A12 = 1.90462E-05, A14 = 0
No. 43
K = -30.000, A4 = -1.42230E-02, A6 = -1.55390E-03, A8 = 2.10850E-03, A10 = -1.98640E-04, A12 = -2.53760E-05, A14 = 2.88000E-06
44th page
K = -12.523, A4 = -3.67836E-02, A6 = 7.25917E-03, A8 = -1.44414E-03, A10 = 1.44444E-04, A12 = -5.03374E-06, A14 = 3.23410E-08

[Table 2-4] Original price
First group focal length 14.811
Second group focal length -6.675
3rd group focal length 20.059
4th focal length 21.946
5th group focal length -31.678
6th focal length 7.922
Main lens focal length 4.327
Magnification ratio of converter lens 2.85

  FIG. 7 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion aberration (c)) at the wide-angle end in Example 2. FIG. 8 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the intermediate position in Example 2. FIG. 9 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of Example 2. This embodiment is combined with a main lens having aberration characteristics shown in FIG.

  In the imaging optical system of Example 2, the second lens group GR2 and the fourth lens group GR4 move along the optical axis direction during zooming from the wide-angle end to the telephoto end, and the distance between the lens groups is changed. Scaling can be performed. More specifically, as it goes from the wide-angle end to the telephoto end, the second lens group GR2 monotonously goes to the main lens side, and the fourth lens group GR4 monotonously goes to the subject side. Further, by moving only the fourth lens group GR4 in the optical axis direction, focusing from infinity to a finite distance (including focal position deviation correction when the object distance changes) can be performed. The primary image formation point position is a position of 0.73 to 0.75 mm closer to the subject side than the main lens side surface of the eleventh lens G11 (paraxial value). In other words, the primary image formation point exists in the eleventh lens G11, and the eleventh lens G11 is a meniscus lens having a paraxial curved surface on the subject side facing a concave surface on the subject side and having a positive refractive power in the lens peripheral portion. A tenth lens G10 having negative refractive power is disposed closer to the subject than the eleventh lens G11.

(Example 3)
Table 3 shows lens data of Example 3. FIG. 10 is a sectional view of the image pickup optical system according to the third embodiment. In the figure, GR1 is a first lens group having a positive refractive power, and includes a first lens G1 having a negative refractive power, a first prism PR1 which is a reflective optical element, and a second lens G2. GR2 is a second lens group having negative refractive power, and includes a third lens G3 and a fourth lens G4. Further, GR3 is a third lens group having a positive refractive power, and includes only the fifth lens G5. GR4 is a fourth lens group having a positive refractive power, and includes a sixth lens G6 and a seventh lens G7 which are cemented lenses (G6 / 7). Further, GR5 is a fifth lens group having a positive refractive power, and includes an eighth lens G8, a ninth lens G9, a tenth lens G10, and an eleventh lens G11. GR6 is a sixth lens group having a positive refractive power, and includes a second prism PR2 that is a reflective optical element, and a twelfth lens G12. G is a main lens provided in the imaging apparatus. S denotes an aperture stop provided on the subject side of the fifth lens G5, and IM denotes an imaging surface of the imaging apparatus. Further, F represents a cover glass, and CG represents a parallel flat plate assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state imaging device, and the like. In the example shown in FIG. 11, the optical axis is bent twice using two reflective optical elements, but the optical axis may be bent once using one reflective optical element as shown in FIG. . The 33rd surface is the aperture stop of the main lens.

[Table 3]
Example 3
Unit mm

[Table 3-1] Optical system data (converter lenses: s1 to s30, main lenses: s31 to s46)
srd nd νd
1 15.965 0.40 1.92286 20.9
2 6.903 2.06
3 infinity 8.01 1.84666 23.8
4 infinity 0.10
5 11.602 1.72 1.71300 53.9
6 -15.738 variable
7 -9.499 0.40 1.82080 42.7
8 3.999 0.74
9 8.754 1.03 1.92286 20.9
10 57.878 variable
11 (Aperture) infinity 0.00
12 9.136 0.86 1.69680 55.5
13 -274.598 variable
14 74.225 1.70 1.69680 55.5
15 -4.361 0.40 1.91082 35.3
16 -8.724 variable
17 -7.447 0.40 1.80518 25.5
18 -23.703 7.94
19 -127.229 2.96 1.54400 56.0
20 -6.685 7.58
21 -4.889 1.81 1.54400 56.0
22 -5.742 0.10
23 2.818 2.00 1.54400 56.0
24 1.696 1.67
25 infinity 6.50 1.84666 23.8
26 infinity 0.10
27 2.465 2.79 1.54400 56.0
28 46.191 0.12
29 infinity 0.79 1.51633 64.1
30 infinity 0.64
31 infinity 0.79 1.51633 64.1
32 infinity 1.17
33 infinity 0.05
34 infinity -0.21
35 1.699 0.63 1.54400 56.0
36 -12.145 0.05
37 3.731 0.28 1.63400 24.0
38 1.483 0.62
39 111.675 0.29 1.63400 24.0
40 -1000000.000 0.36
41 -6.238 0.84 1.54400 56.0
42 -1.174 0.28
43 -8.341 0.45 1.53 100 56.0
44 1.499 0.64
45 infinity 0.30 1.51633 64.1
46 infinity 0.40
47 (image plane) infinity 0.00


[Table 3-2] Values at the wide-angle end, intermediate position, and telephoto end in the combined system of the converter lens and main lens
Focal length 4.31 7.14 12.29
Fno 3.50 3.69 4.02
ω (degrees) 36.53 22.60 13.55
Total lens length 75.0 75.0 75.0
d6 0.324 3.421 6.089
d10 6.065 2.968 0.300
d13 8.006 5.614 3.523
d16 0.867 3.260 5.350

[Table 3-3] Aspheric coefficient Ai and conic constant K of aspheric lens
5th page
K = 0, A4 = -9.32154E-05, A6 = -3.86381E-06, A8 = 4.78503E-07, A10 = -3.47309E-08, A12 = 0, A14 = 0
6th page
K = 0, A4 = 2.54258E-05, A6 = 5.74652E-07, A8 = 1.97019E-08, A10 = -1.91845E-08, A12 = 0, A14 = 0
7th page
K = 0, A4 = 6.02351E-04, A6 = 3.95123E-05, A8 = -9.77111E-06, A10 = 6.05046E-07, A12 = 0, A14 = 0
8th page
K = 0, A4 = -2.80247E-03, A6 = 5.24232E-05, A8 = -2.48727E-05, A10 = 1.47784E-06, A12 = 0, A14 = 0
12th page
K = 0, A4 = -1.19618E-03, A6 = 1.32658E-04, A8 = -6.31743E-06, A10 = 2.40729E-06, A12 = 0, A14 = 0
Side 13
K = 0, A4 = -9.46621E-04, A6 = 1.35917E-04, A8 = -4.29690E-06, A10 = 2.31870E-06, A12 = 0, A14 = 0
14th page
K = 0, A4 = -2.07674E-04, A6 = 1.74908E-05, A8 = 2.51305E-06, A10 = -1.68263E-07, A12 = 0, A14 = 0
19th page
K = 0, A4 = 8.66286E-06, A6 = -6.20764E-06, A8 = -6.33811E-07, A10 = -4.93968E-09, A12 = 0, A14 = 0
20th page
K = 0, A4 = 1.29925E-04, A6 = 1.64293E-05, A8 = -6.99453E-07, A10 = 1.96011E-09, A12 = 0, A14 = 0
21st page
K = -0.034, A4 = -7.60711E-04, A6 = -2.26401E-05, A8 = 1.35964E-06, A10 = 1.89934E-07, A12 = 0, A14 = 0
22nd page
K = -0.047, A4 = -5.68957E-04, A6 = -4.68732E-05, A8 = 5.42726E-08, A10 = 9.57801E-08, A12 = 0, A14 = 0
23rd page
K = -1.010, A4 = -3.92617E-03, A6 = -1.29751E-04, A8 = 6.65164E-07, A10 = 1.38404E-07, A12 = 0, A14 = 0
24th page
K = -2.073, A4 = -3.17886E-04, A6 = -6.76780E-04, A8 = 4.10663E-05, A10 = -8.41279E-07, A12 = 0, A14 = 0
27th page
K = -0.917, A4 = -2.77196E-03, A6 = 6.11127E-05 5.82953E-06 -2.02623E-06 0 0
28th page
K = 15.000, A4 = -2.10998E-03, A6 = 2.10826E-04, A8 = -4.27176E-05, A10 = 1.76553E-06, A12 = 0, A14 = 0
35th page
K = 0.045, A4 = 4.09977E-03, A6 = 3.79437E-03, A8 = -5.05465E-03, A10 = 4.24406E-03, A12 = 0, A14 = 0
36th page
K = 18.502, A4 = 2.86613E-02, A6 = 5.80873E-02, A8 = -1.01850E-01, A10 = 4.98182E-02, A12 = 0, A14 = 0
37th page
K = -29.604, A4 = -5.90776E-02, A6 = 1.89791E-01, A8 = -2.57975E-01, A10 = 1.58022E-01, A12 = -3.47186E-02, A14 = 0
38th page
K = -5.422, A4 = 2.16598E-02, A6 = 1.02042E-01, A8 = -9.43786E-02, A10 = 4.93681E-02, A12 = 0, A14 = 0
39th page
K = -30.000, A4 = -1.20105E-01, A6 = -2.57582E-02, A8 = 5.37367E-02, A10 = 2.83845E-02, A12 = -2.20366E-02, A14 = -3.04436E-05
40th page
K = 9.987, A4 = -1.08113E-01, A6 = 1.17911E-02, A8 = 4.21478E-03, A10 = 3.07758E-02, A12 = -1.13692E-02, A14 = -4.66032E-04
41st page
K = 8.246, A4 = 3.41869E-03, A6 = 2.47140E-02, A8 = -5.38394E-03, A10 = -4.05271E-04, A12 = 1.62304E-04, A14 = 0
42nd
K = -4.235, A4 = -5.01998E-02, A6 = 5.22151E-02, A8 = -1.14003E-02, A10 = 4.64219E-04, A12 = 0, A14 = 0
No. 43
K = 5.654, A4 = -3.75710E-02, A6 = 7.50889E-03, A8 = 1.32115E-03, A10 = -2.70599E-04, A12 = -1.16632E-05, A14 = 0
44th page
K = -8.912, A4 = -5.90906E-02, A6 = 1.60085E-02, A8 = -3.52498E-03, A10 = 4.40814E-04, A12 = -2.45474E-05, A14 = 0

[Table 3-4] Original price
First group focal length 12.165
Second group focal length -5.361
3rd group focal length 12.663
Fourth group focal length 15.363
5th focal length 138.180
6th focal length 4.660
Main lens focal length 4.315
Magnification ratio of converter lens 2.85

  FIG. 13 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the wide-angle end in Example 3. FIG. 14 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the intermediate position in Example 3. FIG. 15 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of Example 3. This embodiment is combined with a main lens having aberration characteristics shown in FIG.

  In the imaging optical system of Example 3, the second lens group GR2 and the fourth lens group GR4 move along the optical axis direction during zooming from the wide-angle end to the telephoto end, and the distance between the lens groups is changed. Scaling can be performed. More specifically, as it goes from the wide-angle end to the telephoto end, the second lens group GR2 monotonously goes to the main lens side, and the fourth lens group GR4 monotonously goes to the subject side. Further, by moving only the fourth lens group GR4 in the optical axis direction, focusing from infinity to a finite distance (including focal position deviation correction when the object distance changes) can be performed. The primary image formation point position is 0.50 to 0.53 mm from the main lens side surface of the eleventh lens G11 to the main lens side (paraxial value). In other words, the eleventh lens G11 is a meniscus lens having a convex surface facing the subject side toward the subject side from the primary image forming point, and the tenth lens G10 is a meniscus lens having a concave surface facing the subject side. The combined focal length of the lens arranged on the main lens side from the primary image forming point has a positive value.

Example 4
Table 4 shows lens data of Example 4. FIG. 16 is a cross-sectional view of the image pickup optical system according to the fourth embodiment. In the figure, GR1 is a first lens group having a positive refractive power, and includes a first lens G1 having a negative refractive power, a first prism PR1 which is a reflective optical element, and a second lens G2. GR2 is a second lens group having negative refractive power, and includes a third lens G3, and a fourth lens G4 and a fifth lens G5 which are cemented lenses (G4 / 5). Further, GR3 is a third lens group having a positive refractive power, and includes only the sixth lens G6. GR4 is a fourth lens group having a positive refractive power, and includes a seventh lens G7 and an eighth lens G8 which are cemented lenses (G7 / 8). Further, GR5 is a fifth lens group having a negative refractive power, and includes a ninth lens G9, a tenth lens G10, an eleventh lens G11, and a twelfth lens G12. GR6 is a sixth lens group having a positive refractive power, and includes a second prism PR2 that is a reflective optical element, and a thirteenth lens G13. G is a main lens provided in the imaging apparatus. S denotes an aperture stop provided on the subject side of the sixth lens G6, and IM denotes an imaging surface of the imaging apparatus. Further, F represents a cover glass, and CG represents a parallel flat plate assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state imaging device, and the like. In this embodiment, the optical axis is bent twice. The 34th surface is the aperture stop of the main lens.

[Table 4]
Example 4
Unit mm

[Table 4-1] Optical system data (converter lenses: s1 to s31, main lenses: s32 to s47)
srd nd νd
1 37.039 0.50 1.84666 23.8
2 10.441 1.89
3 infinity 8.49 1.84666 23.8
4 infinity 0.10
5 10.870 1.53 1.69680 55.5
6 -33.237 variable
7 -143.412 0.45 1.84666 23.8
8 5.686 1.07
9 -12.939 0.45 1.61800 63.4
10 6.580 1.11 1.92286 20.9
11 129.468 variable
12 (Aperture) infinity 0.00
13 8.602 0.91 1.69680 55.5
14 63.712 variable
15 63.110 2.11 1.69680 55.5
16 -4.131 0.50 1.91082 35.3
17 -7.951 variable
18 -9.866 0.50 1.80000 29.8
19 -265.264 8.11
20 124.277 2.74 1.54400 56.0
21 -7.317 6.53
22 -4.077 2.70 1.54400 56.0
23 -9.923 0.98
24 2.667 1.53 1.54400 56.0
25 2.380 1.68
26 infinity 6.52 1.84666 23.8
27 infinity 0.10
28 2.274 2.45 1.54400 56.0
29 9.724 0.48
30 infinity 0.79 1.51633 64.1
31 infinity 0.64
32 infinity 0.79 1.51633 64.1
33 infinity 1.17
34 infinity 0.05
35 infinity -0.24
36 1.676 0.63 1.54400 56.0
37 -13.857 0.05
38 4.012 0.28 1.63400 24.0
39 1.559 0.57
40 -36.876 0.31 1.63400 24.0
41 -35.075 0.42
42 -6.434 0.86 1.54400 56.0
43 -0.965 0.23
44 -2.637 0.45 1.53 100 56.0
45 1.582 0.64
46 infinity 0.30 1.51633 64.1
47 infinity 0.40
48 (image plane) infinity 0.00


[Table 4-2] Values at the wide-angle end, intermediate position, and telephoto end in the combined system of the converter lens and main lens
Focal length 5.18 8.95 15.15
Fno 3.50 3.70 4.03
ω (degrees) 31.67 18.59 11.10
Total lens length 77.0 77.0 77.0
d6 0.831 4.901 7.962
d11 8.152 4.082 1.020
d14 5.502 3.637 1.910
d17 0.756 2.621 4.348

[Table 4-3] Aspheric coefficient Ai and conic constant K of aspheric lens
5th page
K = 0, A4 = -1.71824E-04, A6 = -3.73199E-06, A8 = 4.17804E-07, A10 = -2.41056E-08, A12 = 0, A14 = 0
6th page
K = 0, A4 = -1.07424E-04, A6 = 7.00272E-07, A8 = 1.42215E-07, A10 = -1.66422E-08, A12 = 0, A14 = 0
Side 13
K = 0, A4 = -9.40079E-04, A6 = 5.40616E-05, A8 = -1.40895E-05, A10 = 1.53946E-06, A12 = 0, A14 = 0
14th page
K = 0, A4 = -8.08773E-04, A6 = 5.72617E-05, A8 = -1.32749E-05, A10 = 1.51174E-06, A12 = 0, A14 = 0
15th page
K = 0, A4 = -3.16962E-04, A6 = 1.01842E-05, A8 = 1.13118E-06, A10 = 4.58449E-09, A12 = 0, A14 = 0
20th page
K = 0, A4 = -1.47248E-04, A6 = 3.78046E-06, A8 = -3.69954E-07, A10 = -2.68225E-08, A12 = 0, A14 = 0
21st page
K = 0, A4 = -1.53905E-04, A6 = 2.51344E-05, A8 = -7.87951E-07, A10 = -8.13875E-09, A12 = 0, A14 = 0
22nd page
K = 0.029, A4 = -1.58738E-03, A6 = -2.04196E-04, A8 = 1.36168E-05, A10 = 9.82581E-07, A12 = 0, A14 = 0
23rd page
K = -19.028, A4 = -6.69722E-03, A6 = 1.01692E-04, A8 = -1.41049E-06, A10 = 1.19489E-07, A12 = 0, A14 = 0
24th page
K = -1.044, A4 = -4.99322E-03, A6 = -1.83169E-04, A8 = 1.25605E-06, A10 = 3.39502E-07, A12 = 0, A14 = 0
25th page
K = -3.093, A4 = 1.66246E-04, A6 = -6.78063E-04, A8 = 3.69487E-05, A10 = -6.17737E-07, A12 = 0, A14 = 0
28th page
K = -0.845, A4 = -1.84649E-03, A6 = 1.53689E-04, A8 = 1.90970E-06, A10 = -2.33417E-06, A12 = 0, A14 = 0
29th page
K = 0.519, A4 = -1.41034E-03, A6 = 7.27442E-05, A8 = -4.22957E-05, A10 = 2.27019E-06, A12 = 0, A14 = 0
36th page
K = -0.025, A4 = 5.47370E-03, A6 = 1.88020E-03, A8 = -3.19280E-03, A10 = 1.70370E-02, A12 = -2.18680E-02, A14 = 8.42100E-03
37th page
K = -29.823, A4 = 2.98640E-02, A6 = 3.68780E-02, A8 = -4.32080E-02, A10 = -2.39990E-02, A12 = 2.70620E-02, A14 = 0
38th page
K = -30.000, A4 = -4.44840E-02, A6 = 1.45640E-01, A8 = -1.27280E-01, A10 = -3.26040E-02, A12 = 7.77900E-02, A14 = -1.88760E-02
39th page
K = -6.295, A4 = 4.79850E-02, A6 = 5.18720E-02, A8 = -1.88520E-02, A10 = -6.35010E-03, A12 = -4.10750E-03, A14 = 2.20700E-02
40th page
K = 30.000, A4 = -1.22180E-01, A6 = -2.65360E-02, A8 = 6.23540E-02, A10 = 2.03720E-02, A12 = -1.85540E-02, A14 = -6.33860E-04
41st page
K = 30.000, A4 = -1.00270E-01, A6 = 3.06270E-03, A8 = 1.91060E-02, A10 = 1.60540E-02, A12 = -2.27710E-03, A14 = -2.79440E-03
42nd
K = 7.826, A4 = -3.77240E-04, A6 = 2.04210E-02, A8 = -1.10470E-03, A10 = -1.62070E-03, A12 = 2.64450E-04, A14 = 0
No. 43
K = -4.059, A4 = -4.31848E-02, A6 = 5.15777E-02, A8 = -1.18416E-02, A10 = 6.53179E-04, A12 = 1.90462E-05, A14 = 0
44th page
K = -30.000, A4 = -1.42230E-02, A6 = -1.55390E-03, A8 = 2.10850E-03, A10 = -1.98640E-04, A12 = -2.53760E-05, A14 = 2.88000E-06
45th page
K = -12.523, A4 = -3.67836E-02, A6 = 7.25917E-03, A8 = -1.44414E-03, A10 = 1.44444E-04, A12 = -5.03374E-06, A14 = 3.23410E-08

[Table 4-4] Original price
First group focal length 17.036
Second group focal length -6.112
3rd group focal length 14.130
4th focal length 13.480
5th group focal length -136.002
6th group focal length 4.866
Main lens focal length 4.327
Magnification ratio of converter lens 2.92

  FIG. 17 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the wide-angle end in Example 4. FIG. 18 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the intermediate position in Example 4. FIG. 19 shows aberration diagrams (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of Example 4. This embodiment is combined with a main lens having aberration characteristics shown in FIG.

  In the imaging optical system of Example 4, the second lens group GR2 and the fourth lens group GR4 move along the optical axis direction during zooming from the wide-angle end to the telephoto end, and the distance between the lens groups is changed. Scaling can be performed. More specifically, as it goes from the wide-angle end to the telephoto end, the second lens group GR2 monotonously goes to the main lens side, and the fourth lens group GR4 monotonously goes to the subject side. Further, by moving only the fourth lens group GR4 in the optical axis direction, focusing from infinity to a finite distance (including focal position deviation correction when the object distance changes) can be performed. The primary image formation point position is a position of -0.00 to 0.02 mm (paraxial value) from the main lens side surface of the twelfth lens G12 to the main lens side. That is, in the telephoto end state, the twelfth lens G12 is a meniscus lens having a convex surface toward the subject side from the primary imaging point toward the subject side, and the eleventh lens G11 has a concave surface toward the subject side. The combined focal length of the lens disposed on the main lens side from the primary image forming point has a positive value. On the other hand, the primary image formation point exists in the twelfth lens G12 at the wide-angle end or in the intermediate state.

(Example 5)
Table 5 shows lens data of Example 5. FIG. 20 is a cross-sectional view of the image pickup optical system according to the fifth embodiment. In the figure, GR1 is a first lens group having a positive refractive power, and includes a first lens G1 having a negative refractive power, a first prism PR1 which is a reflective optical element, and a second lens G2. GR2 is a second lens group having negative refractive power, and includes a third lens G3, and a fourth lens G4 and a fifth lens G5 which are cemented lenses (G4 / 5). Further, GR3 is a third lens group having a positive refractive power, and includes only the sixth lens G6. GR4 is a fourth lens group having a positive refractive power, and includes a seventh lens G7 and an eighth lens G8 which are cemented lenses (G7 / 8). Further, GR5 is a fifth lens group having a positive refractive power, and includes a ninth lens G9, a tenth lens G10, and an eleventh lens G11. GR6 is a sixth lens group having a positive refractive power, and includes a twelfth lens G12, a second prism PR2 that is a reflective optical element, and a thirteenth lens G13. G is a main lens provided in the imaging apparatus. S denotes an aperture stop provided on the subject side of the sixth lens G6, and IM denotes an imaging surface of the imaging apparatus. Further, F represents a cover glass, and CG represents a parallel flat plate assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state imaging device, and the like. In this embodiment, the optical axis is bent twice. The 34th surface is the aperture stop of the main lens.

[Table 5]
Example 5
Unit mm

[Table 5-1] Optical system data (converter lenses: s1 to s31, main lenses: s32 to s47) srd nd νd
1 15.621 0.60 1.92286 20.8
2 8.623 2.65
3 infinity 9.36 1.84666 23.8
4 infinity 0.15
5 12.501 2.00 1.69680 55.5
6 -26.323 variable
7 22.435 0.45 1.91082 35.2
8 4.926 1.46
9 -5.534 0.73 1.63980 34.5
10 8.925 1.11 1.92286 20.9
11 -23.226 variable
12 (Aperture) infinity 0.00
13 13.035 0.92 1.72903 54.0
14 -34.605 variable
15 20.928 2.50 1.69680 55.5
16 -4.704 0.50 1.90366 31.3
17 -10.383 variable
18 97.400 1.50 1.80610 33.2
19 6.117 4.86
20 18.706 3.00 1.54400 56.0
21 -6.986 6.96
22 -2.986 3.50 1.54400 56.0
23 -3.806 3.25
24 -2.924 1.20 1.54400 56.0
25 -3.245 0.15
26 infinity 7.00 2.00100 29.1
27 infinity 0.15
28 2.637 1.99 1.54400 56.0
29 8.021 0.52
30 infinity 0.79 2.00 100 29.1
31 infinity 0.64
32 infinity 0.79 1.51633 64.1
33 infinity 1.23
34 infinity 0.05
35 infinity -0.24
36 1.676 0.63 1.54400 56.0
37 -13.857 0.05
38 4.012 0.28 1.63400 24.0
39 1.559 0.57
40 -36.876 0.31 1.63400 24.0
41 -35.075 0.42
42 -6.434 0.86 1.54400 56.0
43 -0.965 0.23
44 -2.637 0.45 1.53 100 56.0
45 1.582 0.64
46 infinity 0.30 1.51633 64.1
47 infinity 0.40
48 (image plane) infinity 0.00


[Table 5-2] Values at the wide-angle end, intermediate position, and telephoto end in the combined system of the converter lens and main lens
Focal length 5.18 8.93 15.12
Fno 3.50 3.71 4.02
ω (degrees) 31.19 18.37 11.05
Total lens length 77.9 77.9 77.9
d6 0.570 4.292 7.146
d11 7.456 3.733 0.880
d14 4.506 2.838 1.330
d17 0.446 2.115 3.622

[Table 5-3] Aspheric coefficient Ai and conic constant K of aspheric lens
5th page
K = 0, A4 = -1.75736E-04, A6 = 6.02264E-06, A8 = -2.48670E-07, A10 = 1.11824E-08, A12 = 0, A14 = 0
6th page
K = 0, A4 = -1.57684E-04, A6 = 8.94028E-06, A8 = -3.21281E-07, A10 = 1.21123E-08, A12 = 0, A14 = 0
Side 13
K = 0, A4 = -8.89774E-04, A6 = 2.47040E-05, A8 = -7.60949E-06, A10 = 4.46028E-07, A12 = 0, A14 = 0
14th page
K = 0, A4 = -4.76170E-04, A6 = 2.15137E-05, A8 = -5.13759E-06, A10 = 2.34123E-07, A12 = 0, A14 = 0
15th page
K = 0, A4 = 1.38336E-05, A6 = 9.03814E-06, A8 = 1.75245E-06, A10 = -1.08828E-07, A12 = 0, A14 = 0
20th page
K = 0, A4 = -9.99322E-05, A6 = 6.62683E-06, A8 = -4.84661E-07, A10 = 3.69182E-08, A12 = 0, A14 = 0
21st page
K = 0, A4 = -1.09097E-04, A6 = 2.85658E-05, A8 = -1.16360E-06, A10 = 5.09636E-08, A12 = 0, A14 = 0
22nd page
K = -0.639, A4 = -7.79329E-03, A6 = 3.73677E-04, A8 = 4.29952E-05, A10 = -1.84405E-06, A12 = 0, A14 = 0
23rd page
K = -2.424, A4 = -5.96106E-03, A6 = 2.40377E-04, A8 = -8.10144E-06, A10 = 2.69969E-07, A12 = 0, A14 = 0
24th page
K = -16.052, A4 = 6.00388E-03, A6 = -3.79094E-04, A8 = 1.64742E-05, A10 = -2.70215E-07, A12 = 0, A14 = 0
25th page
K = -9.744, A4 = 4.03698E-03, A6 = -2.95322E-04, A8 = 9.79589E-06, A10 = -6.90469E-08, A12 = 0, A14 = 0
28th page
K = -0.668, A4 = 3.79459E-03, A6 = -5.08217E-04, A8 = 7.16598E-05, A10 = -8.14102E-06, A12 = 0, A14 = 0
29th page
K = 3.729, A4 = -1.04420E-03, A6 = -2.92268E-04, A8 = -4.49300E-05, A10 = 3.32644E-06, A12 = 0, A14 = 0
36th page
K = -0.025, A4 = 5.47370E-03, A6 = 1.88020E-03, A8 = -3.19280E-03, A10 = 1.70370E-02, A12 = -2.18680E-02, A14 = 8.42100E-03
37th page
K = -29.823, A4 = 2.98640E-02, A6 = 3.68780E-02, A8 = -4.32080E-02, A10 = -2.39990E-02, A12 = 2.70620E-02, A14 = 0
38th page
K = -30.000, A4 = -4.44840E-02, A6 = 1.45640E-01, A8 = -1.27280E-01, A10 = -3.26040E-02, A12 = 7.77900E-02, A14 = -1.88760E-02
39th page
K = -6.295, A4 = 4.79850E-02, A6 = 5.18720E-02, A8 = -1.88520E-02, A10 = -6.35010E-03, A12 = -4.10750E-03, A14 = 2.20700E-02
40th page
K = 30.000, A4 = -1.22180E-01, A6 = -2.65360E-02, A8 = 6.23540E-02, A10 = 2.03720E-02, A12 = -1.85540E-02, A14 = -6.33860E-04
41st page
K = 30.000, A4 = -1.00270E-01, A6 = 3.06270E-03, A8 = 1.91060E-02, A10 = 1.60540E-02, A12 = -2.27710E-03, A14 = -2.79440E-03
42nd
K = 7.826, A4 = -3.77240E-04, A6 = 2.04210E-02, A8 = -1.10470E-03, A10 = -1.62070E-03, A12 = 2.64450E-04, A14 = 0
No. 43
K = -4.059, A4 = -4.31848E-02, A6 = 5.15777E-02, A8 = -1.18416E-02, A10 = 6.53179E-04, A12 = 1.90462E-05, A14 = 0
44th page
K = -30.000, A4 = -1.42230E-02, A6 = -1.55390E-03, A8 = 2.10850E-03, A10 = -1.98640E-04, A12 = -2.53760E-05, A14 = 2.88000E-06
45th page
K = -12.523, A4 = -3.67836E-02, A6 = 7.25917E-03, A8 = -1.44414E-03, A10 = 1.44444E-04, A12 = -5.03374E-06, A14 = 3.23410E-08

[Table 5-4] Original price
First group focal length 15.699
Second group focal length -5.515
3rd group focal length 13.050
4th focal length 13.435
5th group focal length 14.994
6th focal length 5.466
Main lens focal length 4.327
Magnification ratio of converter lens 2.92

  FIG. 21 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the wide-angle end in Example 5. FIG. 22 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the intermediate position in Example 5. FIG. 23 shows aberration diagrams (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of Example 5. This embodiment is combined with a main lens having aberration characteristics shown in FIG.

  In the imaging optical system of Example 5, the second lens group GR2 and the fourth lens group GR4 move along the optical axis direction during zooming from the wide-angle end to the telephoto end, and the interval between the lens groups is changed. Scaling can be performed. More specifically, as it goes from the wide-angle end to the telephoto end, the second lens group GR2 monotonously goes to the main lens side, and the fourth lens group GR4 monotonously goes to the subject side. Further, by moving only the fourth lens group GR4 in the optical axis direction, focusing from infinity to a finite distance (including focal position deviation correction when the object distance changes) can be performed. The primary image formation point position is a position of 1.57 to 1.59 mm from the main lens side surface of the eleventh lens G11 to the main lens side (paraxial value). That is, the eleventh lens G11 is a meniscus lens having a concave surface directed toward the subject from the primary imaging point toward the subject, and the tenth lens G10 is a lens having a positive refractive power.

(Example 6)
Table 6 shows lens data of Example 6. FIG. 24 is a cross-sectional view of the image pickup optical system according to the sixth embodiment. In the figure, GR1 is a first lens group having a positive refractive power, and includes a first lens G1 having a negative refractive power, a first prism PR1 which is a reflective optical element, and a second lens G2. GR2 is a second lens group having negative refractive power, and includes a third lens G3, and a fourth lens G4 and a fifth lens G5 which are cemented lenses (G4 / 5). Further, GR3 is a third lens group having a positive refractive power, and includes only the sixth lens G6. GR4 is a fourth lens group having a positive refractive power, and includes a seventh lens G7 and an eighth lens G8 which are cemented lenses (G7 / 8). Further, GR5 is a fifth lens group having a positive refractive power, and includes a ninth lens G9, a tenth lens G10, and an eleventh lens G11. GR6 is a sixth lens group having a positive refractive power, and includes a twelfth lens G12, a second prism PR2 that is a reflective optical element, and a thirteenth lens G13. G is a main lens provided in the imaging apparatus. S denotes an aperture stop provided on the subject side of the sixth lens G6, and IM denotes an imaging surface of the imaging apparatus. Further, F represents a cover glass, and CG represents a parallel flat plate assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state imaging device, and the like. In this embodiment, the optical axis is bent twice. The 34th surface is the aperture stop of the main lens.

[Table 6]
Example 6
Unit mm

[Table 6-1] Optical system data (converter lenses: s1 to s31, main lenses: s32 to s47)
srd nd νd
1 21.627 1.50 1.92286 20.8
2 10.219 2.41
3 infinity 9.84 1.84666 23.8
4 infinity 0.20
5 11.272 2.18 1.69680 55.5
6 -38.720 variable
7 16.217 0.59 1.91082 35.2
8 4.704 1.51
9 -5.417 0.69 1.63980 34.5
10 8.950 1.00 1.92286 20.9
11 -21.161 variable
12 (Aperture) infinity 0.00
13 12.713 0.90 1.72903 54.0
14 -32.896 variable
15 35.646 2.23 1.69680 55.5
16 -4.339 0.50 1.90366 31.3
17 -9.315 variable
18 -75.891 1.87 1.80610 33.2
19 8.508 7.70
20 12.267 3.23 1.54400 56.0
21 -12.654 6.85
22 -4.659 3.87 1.54400 56.0
23 -2.987 2.44
24 -3.343 1.20 1.54400 56.0
25 -37.692 0.20
26 infinity 6.66 2.00100 29.1
27 infinity 0.20
28 2.073 2.85 1.54400 56.0
29 4.972 0.31
30 infinity 0.79 2.00 100 29.1
31 infinity 0.64
32 infinity 0.79 1.51633 64.1
33 infinity 1.23
34 infinity 0.05
35 infinity -0.24
36 1.676 0.63 1.54400 56.0
37 -13.857 0.05
38 4.012 0.28 1.63400 24.0
39 1.559 0.57
40 -36.876 0.31 1.63400 24.0
41 -35.075 0.42
42 -6.434 0.86 1.54400 56.0
43 -0.965 0.23
44 -2.637 0.45 1.53 100 56.0
45 1.582 0.64
46 infinity 0.30 1.51633 64.1
47 infinity 0.40
48 (image plane) infinity 0.00


[Table 6-2] Values at the wide-angle end, intermediate position, and telephoto end in the combined system of the converter lens and main lens
Focal length 5.25 8.70 15.15
Fno 3.50 3.71 4.02
ω (degrees) 31.19 19.02 11.08
Total lens length 82.6 82.6 82.6
d6 0.500 4.154 7.389
d11 7.689 4.035 0.800
d14 4.588 2.971 1.435
d17 0.512 2.128 3.664

[Table 6-3] Aspheric coefficient Ai and conic constant K of aspheric lens
5th page
K = 0, A4 = -1.71908E-04, A6 = 4.54800E-06, A8 = -2.10454E-07, A10 = 9.03645E-09, A12 = 0, A14 = 0
6th page
K = 0, A4 = -1.36167E-04, A6 = 7.71668E-06, A8 = -3.03832E-07, A10 = 1.13269E-08, A12 = 0, A14 = 0
Side 13
K = 0, A4 = -8.13443E-04, A6 = 1.05428E-05, A8 = -8.23793E-06, A10 = 3.13420E-07, A12 = 0, A14 = 0
14th page
K = 0, A4 = -4.96705E-04, A6 = 1.41730E-05, A8 = -8.14517E-06, A10 = 2.81754E-07, A12 = 0, A14 = 0
15th page
K = 0, A4 = -1.61023E-05, A6 = 1.63712E-05, A8 = -1.80918E-07, A10 = 3.12183E-08, A12 = 0, A14 = 0
20th page
K = 0, A4 = 6.14091E-06, A6 = 6.42750E-06, A8 = -7.33228E-07, A10 = 2.08796E-08, A12 = 0, A14 = 0
21st page
K = 0, A4 = -2.99452E-04, A6 = 2.03834E-05, A8 = -1.03236E-06, A10 = 2.60639E-08, A12 = 0, A14 = 0
22nd page
K = -0.491, A4 = -6.94470E-03, A6 = 2.42922E-04, A8 = 2.18285E-05, A10 = -8.75545E-07, A12 = 0, A14 = 0
23rd page
K = -2.172, A4 = -3.01159E-03, A6 = 9.86810E-05, A8 = -1.87775E-06, A10 = 1.35219E-07, A12 = 0, A14 = 0
24th page
K = -7.738, A4 = 7.37673E-03, A6 = -4.61954E-04, A8 = 1.74649E-05, A10 = -2.03277E-07, A12 = 0, A14 = 0
25th page
K = 17.000, A4 = 2.39589E-03, A6 = -2.53177E-04, A8 = 9.52545E-06, A10 = -1.78921E-08, A12 = 0, A14 = 0
28th page
K = -0.866, A4 = -2.56581E-03, A6 = 1.43162E-04, A8 = 4.20601E-06, A10 = -5.65006E-06, A12 = 0, A14 = 0
29th page
K = 0.174, A4 = -6.01766E-03, A6 = -5.08558E-04, A8 = -4.34455E-05, A10 = 5.98598E-06, A12 = 0, A14 = 0
36th page
K = -0.025, A4 = 5.47370E-03, A6 = 1.88020E-03, A8 = -3.19280E-03, A10 = 1.70370E-02, A12 = -2.18680E-02, A14 = 8.42100E-03
37th page
K = -29.823, A4 = 2.98640E-02, A6 = 3.68780E-02, A8 = -4.32080E-02, A10 = -2.39990E-02, A12 = 2.70620E-02, A14 = 0
38th page
K = -30.000, A4 = -4.44840E-02, A6 = 1.45640E-01, A8 = -1.27280E-01, A10 = -3.26040E-02, A12 = 7.77900E-02, A14 = -1.88760E-02
39th page
K = -6.295, A4 = 4.79850E-02, A6 = 5.18720E-02, A8 = -1.88520E-02, A10 = -6.35010E-03, A12 = -4.10750E-03, A14 = 2.20700E-02
40th page
K = 30.000, A4 = -1.22180E-01, A6 = -2.65360E-02, A8 = 6.23540E-02, A10 = 2.03720E-02, A12 = -1.85540E-02, A14 = -6.33860E-04
41st page
K = 30.000, A4 = -1.00270E-01, A6 = 3.06270E-03, A8 = 1.91060E-02, A10 = 1.60540E-02, A12 = -2.27710E-03, A14 = -2.79440E-03
42nd
K = 7.826, A4 = -3.77240E-04, A6 = 2.04210E-02, A8 = -1.10470E-03, A10 = -1.62070E-03, A12 = 2.64450E-04, A14 = 0
No. 43
K = -4.059, A4 = -4.31848E-02, A6 = 5.15777E-02, A8 = -1.18416E-02, A10 = 6.53179E-04, A12 = 1.90462E-05, A14 = 0
44th page
K = -30.000, A4 = -1.42230E-02, A6 = -1.55390E-03, A8 = 2.10850E-03, A10 = -1.98640E-04, A12 = -2.53760E-05, A14 = 2.88000E-06
45th page
K = -12.523, A4 = -3.67836E-02, A6 = 7.25917E-03, A8 = -1.44414E-03, A10 = 1.44444E-04, A12 = -5.03374E-06, A14 = 3.23410E-08

[Table 6-4] Original price
First group focal length 16.680
Second group focal length -5.850
3rd group focal length 12.683
4th focal length 14.641
5th group focal length 4.793
6th focal length 5.913
Main lens focal length 4.327
Magnification ratio of converter lens 2.89

  FIG. 25 shows aberration diagrams (spherical aberration (a), astigmatism (b), distortion aberration (c)) at the wide-angle end in Example 6. FIG. 26 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the intermediate position in Example 6. FIG. 27 shows aberration diagrams (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of Example 6. This embodiment is combined with a main lens having aberration characteristics shown in FIG.

  In the imaging optical system of Example 6, the second lens group GR2 and the fourth lens group GR4 move along the optical axis direction during zooming from the wide-angle end to the telephoto end, and the distance between the lens groups is changed. Scaling can be performed. More specifically, as it goes from the wide-angle end to the telephoto end, the second lens group GR2 monotonously goes to the main lens side, and the fourth lens group GR4 monotonously goes to the subject side. Further, by moving only the fourth lens group GR4 in the optical axis direction, focusing from infinity to a finite distance (including focal position deviation correction when the object distance changes) can be performed. The primary image formation point position is a position of 0.86 to 0.87 mm from the main lens side surface of the eleventh lens G11 to the main lens side (paraxial value). That is, the eleventh lens G11 is a meniscus lens having a concave surface directed toward the subject from the primary imaging point toward the subject, and the tenth lens G10 is a lens having a positive refractive power.

(Example 7)
Table 7 shows lens data of Example 7. FIG. 28 is a sectional view of the image pickup optical system according to the seventh embodiment. In the figure, GR1 is a first lens group having a positive refractive power, and includes a first lens G1 having a negative refractive power, a first prism PR1 which is a reflective optical element, and a second lens G2. GR2 is a second lens group having negative refractive power, and includes a third lens G3, and a fourth lens G4 and a fifth lens G5 which are cemented lenses (G4 / 5). Further, GR3 is a third lens group having a positive refractive power, and includes only the sixth lens G6. GR4 is a fourth lens group having a positive refractive power, and includes a seventh lens G7 and an eighth lens G8 which are cemented lenses (G7 / 8). Further, GR5 is a fifth lens group having a positive refractive power, and includes a ninth lens G9, a tenth lens G10, and an eleventh lens G11. GR6 is a sixth lens group having a positive refractive power, and includes a twelfth lens G12, a second prism PR2 that is a reflective optical element, and a thirteenth lens G13. G is a main lens provided in the imaging apparatus. S denotes an aperture stop provided on the subject side of the sixth lens G6, and IM denotes an imaging surface of the imaging apparatus. Further, F represents a cover glass, and CG represents a parallel flat plate assuming an optical low-pass filter, an IR cut filter, a seal glass of a solid-state imaging device, and the like. In this embodiment, the optical axis is bent twice. The 34th surface is the aperture stop of the main lens.

[Table 7]
Example 7
Unit mm

[Table 7-1] Optical system data (converter lenses: s1 to s31, main lenses: s32 to s47)
srd nd νd
1 23.194 1.34 1.92286 20.8
2 10.497 2.30
3 infinity 9.75 1.84666 23.8
4 infinity 0.20
5 12.076 1.99 1.69680 55.5
6 -31.467 variable
7 16.389 0.65 1.91082 35.2
8 4.779 1.63
9 -5.317 0.78 1.63980 34.5
10 9.044 1.16 1.92286 20.9
11 -22.537 variable
12 (Aperture) infinity 0.00
13 20.751 0.90 1.72903 54.0
14 -16.988 variable
15 25.380 2.00 1.69680 55.5
16 -4.475 0.55 1.90366 31.3
17 -9.828 variable
18 -962.075 1.70 1.80610 33.2
19 7.185 8.12
20 16.316 4.33 1.54400 56.0
21 -8.277 6.90
22 -2.926 1.59 1.54400 56.0
23 -4.430 3.05
24 -4.381 3.17 1.54400 56.0
25 -3.021 0.20
26 infinity 7.16 2.00100 29.1
27 infinity 0.20
28 3.723 1.55 1.54400 56.0
29 8.138 0.23
30 infinity 0.79 2.00 100 29.1
31 infinity 0.64
32 infinity 0.79 1.51633 64.1
33 infinity 1.23
34 infinity 0.05
35 infinity -0.24
36 1.676 0.63 1.54400 56.0
37 -13.857 0.05
38 4.012 0.28 1.63400 24.0
39 1.559 0.57
40 -36.876 0.31 1.63400 24.0
41 -35.075 0.42
42 -6.434 0.86 1.54400 56.0
43 -0.965 0.23
44 -2.637 0.45 1.53 100 56.0
45 1.582 0.64
46 infinity 0.30 1.51633 64.1
47 infinity 0.40
48 (image plane) infinity 0.00


[Table 7-2] Values at the wide-angle end, intermediate position, and telephoto end in the combined system of the converter lens and main lens
Focal length 5.25 9.14 15.15
Fno 3.50 3.71 4.02
ω (degrees) 31.27 18.08 11.07
Total lens length 82.9 82.9 82.9
d6 0.500 4.485 7.387
d11 7.687 3.702 0.800
d14 4.362 2.708 1.300
d17 0.474 2.127 3.535

[Table 7-3] Aspheric coefficient Ai and conic constant K of aspheric lens
5th page
K = 0, A4 = -1.85520E-04, A6 = 5.17347E-06, A8 = -2.65058E-07, A10 = 9.34594E-09, A12 = 0, A14 = 0
6th page
K = 0, A4 = -1.44304E-04, A6 = 7.39842E-06, A8 = -3.18695E-07, A10 = 1.04920E-08, A12 = 0, A14 = 0
Side 13
K = 0, A4 = -8.03273E-04, A6 = 4.11576E-06, A8 = -7.35133E-06, A10 = 5.15505E-07, A12 = 0, A14 = 0
14th page
K = 0, A4 = -4.82417E-04, A6 = 8.82056E-06, A8 = -7.34639E-06, A10 = 4.70206E-07, A12 = 0, A14 = 0
15th page
K = 0, A4 = 6.80362E-05, A6 = 1.77251E-05, A8 = -7.89879E-07, A10 = 8.14082E-08, A12 = 0, A14 = 0
20th page
K = 0, A4 = -1.46055E-04, A6 = 1.23795E-05, A8 = -1.01211E-06, A10 = 2.23654E-08, A12 = 0, A14 = 0
21st page
K = 0, A4 = -1.41745E-04, A6 = 2.41422E-05, A8 = -1.05456E-06, A10 = 2.04097E-08, A12 = 0, A14 = 0
22nd page
K = -0.822, A4 = -3.64057E-03, A6 = 2.30715E-04, A8 = 3.31212E-05, A10 = -1.42762E-06, A12 = 0, A14 = 0
23rd page
K = -3.576, A4 = -2.08655E-03, A6 = 6.94208E-05, A8 = -8.29934E-07, A10 = 3.93297E-07, A12 = 0, A14 = 0
24th page
K = -12.533, A4 = 5.06759E-03, A6 = -3.88778E-04, A8 = 1.57553E-05, A10 = -3.26145E-07, A12 = -2.21812E-09, A14 = 2.21105E-10
25th page
K = -1.601, A4 = 4.33351E-03, A6 = -2.75852E-04, A8 = 8.26221E-06, A10 = -1.23762E-07, A12 = -3.26239E-09, A14 = 1.47788E-10
28th page
K = -0.384, A4 = 7.49497E-03, A6 = -9.12002E-04, A8 = 7.22525E-05, A10 = -6.21226E-06, A12 = 8.41388E-17, A14 = 1.53584E-19
29th page
K = 2.104, A4 = -1.75850E-03, A6 = -2.21432E-04, A8 = -2.93812E-05, A10 = 2.24875E-06, A12 = 3.30563E-17, A14 = 1.66139E-19
36th page
K = -0.025, A4 = 5.47370E-03, A6 = 1.88020E-03, A8 = -3.19280E-03, A10 = 1.70370E-02, A12 = -2.18680E-02, A14 = 8.42100E-03
37th page
K = -29.823, A4 = 2.98640E-02, A6 = 3.68780E-02, A8 = -4.32080E-02, A10 = -2.39990E-02, A12 = 2.70620E-02, A14 = 0
38th page
K = -30.000, A4 = -4.44840E-02, A6 = 1.45640E-01, A8 = -1.27280E-01, A10 = -3.26040E-02, A12 = 7.77900E-02, A14 = -1.88760E-02
39th page
K = -6.295, A4 = 4.79850E-02, A6 = 5.18720E-02, A8 = -1.88520E-02, A10 = -6.35010E-03, A12 = -4.10750E-03, A14 = 2.20700E-02
40th page
K = 30.000, A4 = -1.22180E-01, A6 = -2.65360E-02, A8 = 6.23540E-02, A10 = 2.03720E-02, A12 = -1.85540E-02, A14 = -6.33860E-04
41st page
K = 30.000, A4 = -1.00270E-01, A6 = 3.06270E-03, A8 = 1.91060E-02, A10 = 1.60540E-02, A12 = -2.27710E-03, A14 = -2.79440E-03
42nd
K = 7.826, A4 = -3.77240E-04, A6 = 2.04210E-02, A8 = -1.10470E-03, A10 = -1.62070E-03, A12 = 2.64450E-04, A14 = 0
No. 43
K = -4.059, A4 = -4.31848E-02, A6 = 5.15777E-02, A8 = -1.18416E-02, A10 = 6.53179E-04, A12 = 1.90462E-05, A14 = 0
44th page
K = -30.000, A4 = -1.42230E-02, A6 = -1.55390E-03, A8 = 2.10850E-03, A10 = -1.98640E-04, A12 = -2.53760E-05, A14 = 2.88000E-06
45th page
K = -12.523, A4 = -3.67836E-02, A6 = 7.25917E-03, A8 = -1.44414E-03, A10 = 1.44444E-04, A12 = -5.03374E-06, A14 = 3.23410E-08

[Table 7-4] Original price
First group focal length 16.802
Second group focal length -5.758
3rd group focal length 12.943
4th focal length 13.859
5th group focal length 57.464
6th focal length 5.419
Main lens focal length 4.327
Magnification ratio of converter lens 2.89

  FIG. 29 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the wide-angle end in Example 7. FIG. 30 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the intermediate position in Example 7. FIG. 31 is an aberration diagram (spherical aberration (a), astigmatism (b), distortion (c)) at the telephoto end of Example 7. This embodiment is combined with a main lens having aberration characteristics shown in FIG.

  In the imaging optical system of Example 7, the second lens group GR2 and the fourth lens group GR4 move along the optical axis direction during zooming from the wide-angle end to the telephoto end, and the distance between the lens groups is changed. Scaling can be performed. More specifically, as it goes from the wide-angle end to the telephoto end, the second lens group GR2 monotonously goes to the main lens side, and the fourth lens group GR4 monotonously goes to the subject side. Further, by moving only the fourth lens group GR4 in the optical axis direction, it is possible to perform focusing from infinity to a finite distance (including focal position deviation correction when the object distance changes). The primary image formation point position is a position of 1.60 to 1.61 mm from the main lens side surface of the eleventh lens G11 to the main lens side (paraxial value). That is, the eleventh lens G11 is a meniscus lens having a concave surface directed toward the subject from the primary imaging point toward the subject, and the tenth lens G10 is a lens having a positive refractive power.

  Table 8 shows values of the respective examples corresponding to the respective conditional expressions.

  In the present invention, the converter lens is a positive group preceding (the first lens group has a positive refractive power), but it may be a negative group leading such as negative positive / negative or negative positive / negative. This has the advantage that the number of lenses can be reduced even with the same zoom ratio, but the F-number at the telephoto end tends to become dark because the diaphragm moves integrally with the zoom group.

The present invention is not limited to the embodiments described in the specification, and includes other embodiments and modifications for those skilled in the art from the embodiments and technical ideas described in the present specification. it is obvious. For example, even when a dummy lens having substantially no power is further provided, it is within the scope of the present invention.

BD Body BX Case CL Converter lens ML Main lens SF Mobile terminal

Claims (18)

In the converter lens that is arranged on the subject side from the main lens and converts to a shooting angle of view different from the shooting angle of view of the main lens,
The angular magnification of the converter lens is changed by changing magnification by changing the lens interval in the converter lens, and the light beam incident on the converter lens is primary imaged in the converter lens. Then, the converter lens is incident on the main lens, and the converter lens has a reflective optical element for bending an optical path.   2. The converter lens according to claim 1, wherein a meniscus lens having a concave surface directed toward the subject side and a lens having a positive refractive power are disposed in order from the primary image forming point toward the subject side. The converter lens described.   In the converter lens, a meniscus lens having a convex surface on the subject side and a meniscus lens having a concave surface on the subject side are arranged in order from the primary image formation point toward the subject side, and the main lens from the primary image formation point. The converter lens according to claim 1, wherein the combined focal length of the lens disposed on the side has a positive value.   In the converter lens, a primary image forming point exists in the lens, and the lens is a meniscus lens having a convex surface facing the subject side, and a meniscus lens having a concave surface facing the subject side from the meniscus lens. 2. The converter lens according to claim 1, wherein the combined focal length of the lens disposed and disposed closer to the main lens side than the primary imaging point has a positive value. The converter lens according to any one of claims 2 to 4, wherein the meniscus lens having a concave surface directed toward the subject side satisfies the expression (1).
2 <| fMO / fR | <52 (1)
However,
fMO: the focal length of the meniscus lens with the concave surface facing the object side fR: the combined focal length of the lens located on the main lens side from the primary imaging point at the telephoto end of the converter lens The converter lens according to any one of claims 2 to 4, wherein the meniscus lens having a concave surface directed toward the subject side satisfies the expression (2).
−0.5 <SFMO <0.5 (2)
However,
SFMO: A shaping factor of the meniscus lens having a concave surface facing the subject side, which satisfies the following expression.
SFMO = (R1O-R2O) / (R1O + R2O)
Here, R1O is the radius of curvature of the subject side surface of the meniscus lens with the concave surface facing the subject side, and R2O is the radius of curvature of the main lens side surface of the meniscus lens with the concave surface facing the subject side. 5. The converter lens according to claim 3, wherein the meniscus lens having a convex surface facing the subject side satisfies the expression (3). 6.
4 <| fMT / fR | <10 (3)
However,
fMT: Focal length of the meniscus lens having a convex surface facing the object side fR: Composite focal length of a lens located on the main lens side from the primary imaging point at the telephoto end of the converter lens The converter lens according to any one of claims 3, 4, and 7, wherein the meniscus lens having a convex surface facing the subject side satisfies the expression (4).
0 <SFMT <0.3 (4)
However,
SFMT: A shaping factor of the meniscus lens having a convex surface facing the subject side, which satisfies the following expression.
SFMT = (R1T−R2T) / (R1T + R2T)
Where R1T is the radius of curvature of the subject side surface of the meniscus lens with the convex surface facing the subject side, and R2T is the radius of curvature of the main lens side surface of the meniscus lens with the convex surface facing the subject side.   In the converter lens, a primary imaging point exists in the lens, and the lens has a surface formed by a paraxial radius of curvature on the subject side and a concave surface on the subject side, and has a positive refractive power in the periphery of the lens. 2. The converter lens according to claim 1, wherein a lens having a negative refractive power is disposed closer to the subject side than the meniscus lens.   10. The converter lens according to claim 1, wherein the converter lens includes, in order from the main lens side, a lens having a positive refractive power and a reflection optical element for bending an optical path. 10. . The converter lens according to claim 10, wherein the lens having positive refractive power satisfies the expression (5).
0.8 <fRP / fR <2.1 (5)
However,
fMR: focal length of the lens having the positive refractive power fR: synthetic focal length of the lens located on the main lens side from the primary imaging point at the telephoto end in the converter lens   12. The converter lens according to claim 1, wherein the converter lens includes two or less optical elements having refractive power arranged on the main lens side from a primary image formation point. 13. Converter lens.   The converter lens according to any one of claims 1 to 12, wherein the number of reflections for bending the optical path is two or less.   The focal position shift when the object distance changes is corrected by moving a part of the lenses in the converter lens in the optical axis direction. Converter lens.   The converter according to any one of claims 1 to 14, wherein the converter lens includes, in order from the subject side, a lens having a negative refractive power and a reflective optical element for bending the optical path. lens.   Among the converter lenses, lenses positioned closer to the subject side than the primary image forming point at the telephoto end are a positive first lens group, a negative second lens group, a positive third lens group, and a positive lens in order from the subject side. The fourth lens group, the positive fifth lens group, or the positive first lens group, the negative second lens group, the positive third lens group, the positive fourth lens group, and the negative fifth lens group. The zooming is performed by moving the second lens group and the fourth lens group, and an aperture stop is disposed on the subject side or the main lens side of the third lens group. The converter lens according to any one of 1 to 15. An imaging optical system comprising the converter lens according to any one of claims 1 to 16 and a main lens and satisfying the expression (6).
1.0 <fR / fM <2.0 (6)
However,
fM: focal length of the main lens fR: composite focal length of the converter lens located on the main lens side from the primary imaging point at the telephoto end of the converter lens An imaging optical system comprising the converter lens according to any one of claims 1 to 16 and a main lens and satisfying the expression (7).
2.5 <fTOT / fM <4 (7)
However,
fM: focal length of the main lens fTOT: focal length at the telephoto end of the entire system in a state where the converter lens is disposed on the subject side of the main lens