JP2016156941A - Lens system, optical device, and method for manufacturing lens system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact lens system having excellent optical performance, an optical device, and a method for manufacturing the lens system.SOLUTION: A lens system comprises at least two lens groups. The lens group GL closest to an image surface side includes, arranged in order from an object side: a biconvex positive lens component; a positive lens, and a biconcave negative lens disposed closest to the image surface side. The lens system performs focusing by moving the biconvex positive lens component, composing the lens group closest to the image surface side, in an optical axis direction as a focusing lens group, and satisfies the following conditional expression (1): TL/Σd<1.10 ...(1) when TL represents an entire length (a distance from a most frontal lens surface to an image surface on an optical axis) of a lens system IF and Σd represents a distance from the most frontal lens surface to a final lens surface on the optical axis.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lens system, an optical apparatus, and a method for manufacturing a lens system.

  In recent years, an inner focus lens has been proposed (see, for example, Patent Document 1).

JP 2013-218267 A

  In recent years, lens systems are required to have better optical performance.

In order to solve such a problem, the lens system according to the present invention has at least two lens groups, and the lens group closest to the image plane is a biconvex positive lens component arranged in order from the object side. ,
A positive lens and a biconcave negative lens arranged closest to the image plane side, and the biconvex positive lens component constituting the lens group closest to the image plane is used as a focusing lens group. Focusing is performed by moving in the axial direction, and the following conditional expression is satisfied.

TL / Σd <1.10
However,
TL: full length of the lens system (distance from the lens frontmost surface to the image plane on the optical axis),
Σd: Distance from the foremost lens surface to the last lens surface on the optical axis.

  An optical apparatus according to the present invention is equipped with the lens system described above.

The method for manufacturing a lens system according to the present invention is a method for manufacturing a lens system having at least two lens groups, and the most image side lens groups are arranged in order from the object side, and are biconvex positive lens components. And a positive lens and a biconcave negative lens arranged closest to the image plane, and the biconvex positive lens component constituting the lens group closest to the image plane is converted into a focusing lens group. As described above, focusing is performed by moving in the optical axis direction, and each lens is arranged in the lens barrel so as to satisfy the following conditional expression.

TL / Σd <1.10
However,
TL: full length of the lens system (distance from the lens frontmost surface to the image plane on the optical axis),
Σd: Distance from the foremost lens surface to the last lens surface on the optical axis.

It is sectional drawing which shows the structure of the lens system which concerns on 1st Example. FIG. 4 is a diagram illustrating various aberrations of the lens system according to Example 1, wherein (a) shows a focused state at infinity, and (b) shows a short range focused state (shooting magnification β = −1 / 20). It is sectional drawing which shows the structure of the lens system which concerns on 2nd Example. FIG. 6 is a diagram illustrating various aberrations of the lens system according to Example 2, wherein (a) shows a focused state at infinity, and (b) shows a short range focused state (shooting magnification β = −1 / 20). It is sectional drawing which shows the structure of the lens system which concerns on 3rd Example. FIG. 5A is a diagram illustrating various aberrations of the lens system according to Example 3, wherein (a) shows a focused state at infinity, and (b) shows a short range focused state (shooting magnification β = −1 / 20). It is sectional drawing which shows the structure of the lens system which concerns on 4th Example, (a) shows normal mode, (b) shows macro mode. FIG. 9A is a diagram illustrating various aberrations in the normal mode of the lens system according to Example 4, wherein (a) shows an infinite focus state, and (b) shows a short distance focus state (shooting magnification β = −1 / 20). FIG. 10 is a diagram illustrating various aberrations in the macro mode of the lens system according to Example 4, where (a) is in a focused state with an imaging magnification β = −1 / 20, and (b) is an in-focus state with an imaging magnification β = −1 / 7.7. Indicates a burned state. (A) is a front view of a digital still camera, (b) is a rear view of a digital still camera. It is sectional drawing along arrow AA 'in Fig.10 (a). 3 is a flowchart illustrating a method for manufacturing a lens system according to the present embodiment.

Hereinafter, embodiments will be described with reference to the drawings. Lens system I according to this embodiment
As shown in FIG. 1, F has at least two lens groups, and the most image side lens group GL.
Includes a biconvex positive lens component, a positive lens, and a biconcave negative lens arranged closest to the image plane, arranged in order from the object side, and includes a lens group GL closest to the image plane. Focusing is performed by moving the above-described biconvex positive lens component constituting the focusing lens group in the optical axis direction.

  Here, the “lens component” indicates a single lens or a cemented lens.

By configuring the lens system IF according to the present embodiment with two lens groups (G1, G2), it is possible to satisfactorily correct various aberrations such as spherical aberration when focusing on infinity. Aberration variation such as spherical aberration can be reduced when focusing on a short-distance object.

Alternatively, as shown in FIG. 7, by constituting with three or more lens groups (G1, G2, G3), various aberrations such as spherical aberration can be corrected well at the time of focusing on infinity. Aberration variation such as spherical aberration can be reduced when focusing on a short-distance object.

The lens system IF according to the present embodiment includes a biconvex positive lens component, a positive lens, and a biconcave disposed closest to the image plane, in which the lens group GL on the most image plane side is arranged in order from the object side. By constituting with the three components of the negative lens having a shape, various aberrations such as spherical aberration and field curvature can be favorably corrected at the time of focusing on infinity. It is possible to reduce aberration fluctuations such as spherical aberration and curvature of field when focusing on a short distance object.

Alternatively, as shown in FIG. 7, the lens groups GL closest to the image plane are arranged in order from the object side.
Spherical aberration at the time of focusing on infinity by comprising four or more lens components, including a biconvex positive lens component, a positive lens, and a biconcave negative lens located closest to the image plane Various aberrations such as field curvature can be corrected well. It is possible to reduce aberration fluctuations such as spherical aberration and curvature of field when focusing on a short distance object.

  The lens system IF according to the present embodiment satisfies the following conditional expression (1) based on the above configuration.

TL / Σd <1.10 (1)
However,
TL: Full length of the lens system IF (distance from the forefront lens to the image plane on the optical axis),
Σd: Distance from the foremost lens surface to the last lens surface on the optical axis.

Conditional expression (1) defines the lens thickness with respect to the optical total length. By satisfying conditional expression (1), the entire system can be reduced in size. Various aberrations such as spherical aberration can be favorably corrected at the time of focusing on infinity. Aberration variation such as spherical aberration can be reduced when focusing on a short-distance object.

If the upper limit value of the conditional expression (1) is exceeded, the lens system IF is enlarged. Here, the lens system IF
When trying to reduce the size of the lens, it becomes difficult to correct various aberrations such as spherical aberration when focusing on infinity. In addition, aberration fluctuations such as spherical aberration increase when focusing on a short-distance object.

In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 1.06.

  The lens system IF according to the present embodiment preferably satisfies the following conditional expression (2).

0.55 <βR <0.95 (2)
However,
βR: lateral magnification of the lens group GL closest to the image plane side.

  Conditional expression (2) defines the lateral magnification of the lens group GL closest to the image plane.

Exceeding the upper limit of conditional expression (2) makes it difficult to correct various aberrations such as spherical aberration and coma when focusing on infinity. Aberration fluctuations such as spherical aberration and coma increase when focusing on a short distance object.

In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.70.

If the lower limit value of conditional expression (2) is not reached, the lens system IF is enlarged. Here, the lens system IF
When trying to reduce the size of the lens, it becomes difficult to correct various aberrations such as spherical aberration when focusing on infinity. In addition, aberration fluctuations such as spherical aberration increase when focusing on a short-distance object.

In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.56.

  The lens system IF according to the present embodiment preferably satisfies the following conditional expression (3).

2.00 <{1- (βR1) ² } × (βRr) ² × 10 <6.00 (3)
However,
βR1: lateral magnification of a biconvex positive lens component of the lens unit GL closest to the image plane side,
βRr: the combined lateral magnification of the lens disposed on the image plane side with respect to the biconvex positive lens component of the lens group GL closest to the image plane side.

Conditional expression (3) is a conditional expression for focusing with a biconvex positive lens component disposed on the most object side of the lens group GL closest to the image plane side.

If the upper limit of conditional expression (3) is exceeded, the amount of movement of the biconvex positive lens component at the time of focusing is reduced, which is advantageous for downsizing the lens system IF. However, it is difficult to correct various aberrations such as field curvature and astigmatism when focusing on infinity. In addition, aberration fluctuations such as field curvature and astigmatism increase when focusing on a short-distance object.

In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (3) to 5.00.

If the lower limit of conditional expression (3) is not reached, the amount of movement of the biconvex positive lens component at the time of focusing increases, and the lens system IF increases in size. Here, it is difficult to correct various aberrations such as field curvature and astigmatism in order to reduce the size of the lens system IF. In addition, aberration fluctuations such as field curvature and astigmatism increase when focusing on a short-distance object.

In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (3) to 3.00.

  The lens system IF according to the present embodiment preferably satisfies the following conditional expression (4).

GLd / TL <0.30 (4)
However,
GLd: the thickness on the optical axis of the lens group GL closest to the image plane.

Conditional expression (4) defines the thickness of the lens group GL closest to the image plane with respect to the optical total length.

If the upper limit value of the conditional expression (4) is exceeded, the lens system IF becomes larger. Here, the lens system IF
If it is intended to reduce the size of the lens, it becomes difficult to correct various aberrations such as field curvature and astigmatism during focusing at infinity. In addition, aberration fluctuations such as field curvature and astigmatism increase when focusing on a short-distance object.

In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (4) to 0.28.

  The lens system IF according to the present embodiment preferably satisfies the following conditional expression (5).

0.50 <fF / f <10.00 (5)
However,
fF: the combined focal length of the lens unit disposed closer to the object side than the lens unit GL closest to the image plane side
f: Focal length in the entire lens system IF system.

Conditional expression (5) defines the ratio between the focal length of the entire lens system IF and the combined focal length of the lens unit disposed closer to the object side than the lens unit GL closest to the image plane.

If the upper limit value of the conditional expression (5) is exceeded, the lens system IF is enlarged. Here, the lens system IF
When trying to reduce the size of the lens, it becomes difficult to correct various aberrations such as spherical aberration when focusing on infinity. In addition, aberration fluctuations such as spherical aberration increase when focusing on a short-distance object.

In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 5.00. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 3.00. In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 1.86. In order to further secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (5) to 1.70.

If the lower limit value of conditional expression (5) is not reached, it will be difficult to correct various aberrations such as spherical aberration and coma when focusing on infinity. In addition, aberration fluctuations such as spherical aberration and coma increase when focusing on a short-distance object.

In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.80. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 1.00. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 1.20. In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 1.40. In order to further secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (5) to 1.60.

  The lens system IF according to the present embodiment preferably satisfies the following conditional expression (6).

1.00 <fL / f <4.00 (6)
However,
fL: the focal length of the lens unit GL closest to the image plane,
f: Focal length of the entire lens system IF.

Conditional expression (6) defines the ratio between the focal length of the lens group GL closest to the image plane and the focal length of the entire lens system IF.

If the upper limit of conditional expression (6) is exceeded, it will be difficult to correct various aberrations such as spherical aberration when focusing on infinity. In addition, aberration fluctuations such as spherical aberration increase when focusing on a short-distance object.

In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (6) to 3.70.

If the lower limit of conditional expression (6) is not reached, it will be difficult to correct various aberrations such as spherical aberration and coma when focusing at infinity. In addition, aberration fluctuations such as spherical aberration and coma increase when focusing on a short-distance object.

In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (6) to 1.30.

  The lens system IF according to the present embodiment preferably satisfies the following conditional expression (7).

0.15 <d / TL <0.50 (7)
However,
d: Distance from the final surface of the lens unit adjacent to the object side of the lens unit GL closest to the image plane on the optical axis to the forefront surface of the lens unit GL closest to the image plane.

  Conditional expression (7) is a conditional expression for performing focusing.

If the upper limit of conditional expression (7) is exceeded, the distance for focusing becomes too large, and the lens system IF
Increases in size. Here, when trying to reduce the size of the lens system IF, it becomes difficult to correct various aberrations such as spherical aberration when focusing on infinity. In addition, aberration fluctuations such as spherical aberration increase when focusing on a short-distance object.

In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (7) to 0.35.

If the lower limit of conditional expression (7) is not reached, the amount of movement of the focusing lens group (the biconvex positive lens component of the lens group GL closest to the image plane) necessary for focusing cannot be secured. In addition, it becomes difficult to correct various aberrations such as spherical aberration when focusing on infinity. Aberration variation such as spherical aberration increases when focusing on a short-distance object.

In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (7) to 0.16.

In the lens system IF according to the present embodiment, at least a part of the lens group disposed on the object side relative to the lens group GL closest to the image plane is used as an anti-vibration lens group VR to correct image blur. It is preferable to be configured to be movable so as to have a vertical component.

According to this configuration, a space between the actuator of the focusing lens group and the actuator of the image stabilizing lens group VR is secured. In addition, it is possible to reduce the occurrence of decentering coma aberration when the image stabilizing lens group VR moves in the direction perpendicular to the optical axis.

In the lens system IF according to the present embodiment, the anti-vibration lens group VR is a lens arranged closest to the image plane in the lens group arranged closer to the object side than the lens group GL closest to the image plane. Is preferred.

According to this configuration, a space between the actuator of the focusing lens group and the actuator of the image stabilizing lens group VR is secured. In addition, it is possible to reduce the occurrence of decentering coma aberration when the image stabilizing lens group VR moves in the direction perpendicular to the optical axis.

In the lens system IF according to the present embodiment, the anti-vibration lens group VR is preferably any single lens in the lens group disposed closer to the object side than the lens group GL closest to the image plane side.

According to this configuration, a space between the actuator of the focusing lens group and the actuator of the image stabilizing lens group VR is secured. It is possible to reduce the occurrence of decentration coma aberration when the image stabilizing lens group moves in the direction perpendicular to the optical axis. In addition, the vibration-proof lens group can be reduced in size and weight.

  The lens system IF according to the present embodiment preferably satisfies the following conditional expression (8).

0.30 <GFd / TL (8)
GFd: Thickness on the optical axis of the lens unit disposed closer to the object side than the lens unit GL closest to the image plane.

Conditional expression (8) defines the thickness of the lens unit disposed closer to the object side than the lens unit GL closest to the image plane with respect to the entire optical length.

If the lower limit value of conditional expression (8) is not reached, it will be difficult to correct various aberrations such as spherical aberration, coma aberration, and astigmatism when focusing on infinity. In addition, aberration fluctuations such as spherical aberration, coma aberration, and astigmatism during focusing on a short distance object become large.

In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (8) to 0.35.

In the lens system IF according to the present embodiment, it is preferable that the lens group adjacent to the object side with respect to the most image side lens group GL includes at least one positive lens and one negative lens.

According to this configuration, it is possible to correct spherical aberration that occurs in a lens group that is adjacent to the object side relative to the lens group GL that is closest to the image plane.

In the lens system IF according to the present embodiment, it is preferable that the lens group adjacent to the object side of the lens group GL closest to the image plane has at least one cemented lens.

According to this configuration, it is possible to correct axial chromatic aberration that occurs in a lens group that is closer to the object side than the lens group GL that is closest to the image plane.

In the lens system IF according to the present embodiment, it is preferable that the aperture stop S is disposed closer to the object side than the lens group GL closest to the image plane side.

According to this configuration, it is possible to satisfactorily correct various aberrations such as spherical aberration and curvature of field when focusing on infinity. In addition, it is possible to reduce aberration fluctuations such as spherical aberration and field curvature during focusing on a short distance object.

In the lens system IF according to the present embodiment, it is preferable that the aperture stop S is disposed in a lens group adjacent to the object side relative to the lens group GL closest to the image plane.

According to this configuration, it is possible to satisfactorily correct various aberrations such as spherical aberration and curvature of field when focusing on infinity. In addition, it is possible to reduce aberration fluctuations such as spherical aberration and field curvature during focusing on a short distance object.

According to the lens system IF according to the present embodiment having the above-described configuration, it is possible to realize a lens system that is small and has good optical performance.

10 and 11 show the configuration of a digital still camera CAM (optical device) as an optical device including the lens system IF described above. In this digital still camera CAM, when a power button (not shown) is pressed, a shutter (not shown) of the photographing lens (lens system IF) is opened, and the light from the subject (object) is condensed by the lens system IF. Image sensor C arranged on surface I (see FIG. 1)
The image is formed on (for example, CCD or CMOS). The subject image formed on the image sensor C is displayed on the liquid crystal monitor M disposed behind the digital still camera CAM. The photographer
The composition of the subject image is determined while looking at the liquid crystal monitor M, and then the release button B1 is depressed to photograph the subject image with the image sensor C, and record and save it in a memory (not shown). In this way, the photographer can shoot the subject with the camera CAM.

The camera CAM is also provided with an auxiliary light emitting unit EF for emitting auxiliary light when the subject is dark, a function button B2 used for setting various conditions of the digital still camera CAM, and the like.

Here, a compact type camera in which the camera CAM and the lens system IF are integrally formed is illustrated. However, as an optical device, a single lens reflex camera in which a lens barrel having the lens system IF and a camera body main body can be attached and detached is used. good.

According to the camera CAM according to the present embodiment having the above-described configuration, it is possible to realize a small camera having good optical performance by mounting the above-described lens system IF as a photographing lens.

Next, a method for manufacturing the above-described lens system IF will be described with reference to FIG. First, each lens is arranged in a lens barrel so as to have at least two lens groups (
Step ST10). The lens group GL closest to the image plane side has a biconvex positive lens component, a positive lens, and a biconcave negative lens arranged closest to the image plane, arranged in order from the object side. Each lens is arranged (step ST20). The respective lenses are arranged so as to perform focusing by moving the biconvex positive lens component constituting the lens group GL closest to the image plane as the focusing lens group in the optical axis direction (step ST30). Each lens is arranged so as to satisfy the following conditional expression (1) (step ST40).

TL / Σd <1.10 (1)
However,
TL: Full length of the lens system IF (distance from the forefront lens to the image plane on the optical axis),
Σd: Distance from the foremost lens surface to the last lens surface on the optical axis.

As an example of the lens arrangement in the present embodiment, as shown in FIG. 1, a negative meniscus lens L11 having a concave surface directed to the image surface side in order from the object side along the optical axis, a biconvex lens L12, and a biconvex lens L13, a cemented lens of a biconvex lens L14 and a biconcave lens L15, a cemented lens of a biconcave lens L16 and a biconvex lens L17, and a biconvex lens L18 are arranged as a first lens group G1, and a biconvex lens L21, an image Positive meniscus lens L22 having a convex surface facing the surface
And a biconcave lens L23 are arranged to form a second lens group G2. The lens groups prepared in this way are arranged according to the above-described procedure to manufacture the lens system IF.

According to the manufacturing method according to this embodiment as described above, it is possible to manufacture a lens system IF that is small and has good optical performance.

Each example according to the present embodiment will be described with reference to the drawings. 1, 3,
5 and 7 are cross-sectional views showing the configuration and refractive power distribution of the lens system IF (IF1 to IF4) according to each embodiment. In the upper part of the sectional views of the lens systems IF1 to IF4, the moving direction of the focusing lens group when focusing on an object at a short distance from infinity is indicated by an arrow, and the image stabilization lens group VR when correcting image blur is indicated. The situation is also shown.

In addition, each reference code with respect to FIG. 1 according to the first embodiment is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference code. Therefore, even if the same reference numerals as those in the drawings according to the other embodiments are given, they are not necessarily in the same configuration as the other embodiments.

Tables 1 to 4 are shown below, but these are tables of specifications in the first to fourth examples.

In each embodiment, aberration characteristics are calculated using d-line (wavelength 587.6 nm) and g-line (wavelength 435.8 nm).
, C line (wavelength 656.3 nm), F line (wavelength 486.1 nm) are selected.

In [Lens Specifications] in the table, the surface number is the order of the optical surfaces from the object side along the light traveling direction, R is the radius of curvature of each optical surface, D is the next optical surface from each optical surface ( Or an optical surface distance to the image surface), nd is a refractive index of the material of the optical member with respect to the d-line, and νd is an Abbe number based on the d-line of the material of the optical member. The object plane is the object plane, Di (variable) is the variable plane spacing (plane spacing between the i-th plane and the (i + 1) -th plane), (stop S) is the aperture stop S, and the image plane is the image plane I. The radius of curvature “∞” indicates an opening or a plane, respectively. The refractive index of air “1.00000” is omitted. When the optical surface is an aspherical surface, the surface number is marked with *, and the column of curvature radius R indicates the paraxial curvature radius.

In [Aspherical data] in the table, the shape of the aspherical surface shown in [Lens specifications] is shown by the following equation (a). X (y) is the distance along the optical axis direction from the tangential plane at the apex of the aspheric surface to the position on the aspheric surface at height y, R is the radius of curvature of the reference sphere (paraxial radius of curvature), and κ is Ai represents the i-th aspherical coefficient. “E-n” indicates “× 10 ⁻ⁿ ”. For example, 1.234E-05 = 1.234 × 10 ⁻⁵ . The secondary aspherical coefficient A2 is 0, and the description is omitted.

X (y) = (y ² / R) / {1+ (1−κ × y ² / R ² ) ^1/2 } + A4 × y ⁴ + A6 × y ⁶ + A
8 × y ⁸ + A10 × y ¹⁰ (a)

In [Overall specifications] in the table, f is the focal length of the entire lens system, Fno is the F number, ω is the half field angle (unit: °), Y is the image height, and BF is the back focus (on the optical axis). Distance from the last lens surface to the paraxial image plane), BF (air equivalent) is the back focus converted to air, TL
Is the optical total length (distance from the front lens surface to the paraxial image plane on the optical axis), and TL (air conversion) is the total lens length (distance from the front lens surface to the final lens surface on the optical axis). (With back focus added).

In [Variable interval data] in the table, f is the focal length of the entire taking lens system, β is the taking magnification,
Di represents a variable interval between the i-th surface and the (i + 1) -th surface.

In [Lens Group Data] in the table, G represents the group number, the first group surface represents the surface number of the most object side of each group, and the group focal length represents the focal length of each group.

  [Conditional expression] in the table indicates values corresponding to the conditional expressions (1) to (8).

Hereinafter, in all the specification values, “mm” is generally used for the focal length f, curvature radius R, surface distance D, and other lengths, etc. unless otherwise specified, but the optical system is proportionally enlarged. Alternatively, the same optical performance can be obtained even by proportional reduction, and the present invention is not limited to this. Further, the unit is not limited to “mm”, and other appropriate units can be used.

  The description of the table so far is common to all the embodiments, and the description below is omitted.

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 and 2 and Table 1. FIG. As shown in FIG. 1, the lens system IF (IF1) according to the first example includes a first lens group G1 having a positive refractive power arranged in order from the object side along the optical axis, and a positive refractive power. And a second lens group G2 (corresponding to the lens group GL closest to the image plane in claim 1).

The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a concave surface directed toward the image surface side, a biconvex lens L12, a biconvex lens L13, a biconvex lens L14, and a biconcave lens L15. The lens includes a cemented lens, a cemented lens of a biconcave lens L16 and a biconvex lens L17, and a biconvex lens L18. In the biconvex lens L13, both the object side surface and the image side surface are aspherical surfaces. The biconvex lens L18 has an aspheric object side surface.

The second lens group G2 includes, in order from the object side along the optical axis, a biconvex lens L21, a positive meniscus lens L22 having a convex surface directed toward the image plane side, and a biconcave lens L23. The biconvex lens L21 has an aspheric object side surface.

An aperture stop S that determines the brightness is disposed between the biconcave lens L15 and the biconcave lens L16 constituting the first lens group G1.

A filter group FL is disposed between the second lens group G2 and the image plane I. Filter group F
L is composed of a glass block such as a low-pass filter or an infrared cut filter for cutting a spatial frequency equal to or higher than the limit resolution of the solid-state imaging device, such as a CCD disposed on the image plane I.

In the lens system IF1 according to the present embodiment, the lens L21 constituting the second lens group G2 is used as a focusing lens group, and focusing from an infinite distance to a short distance object is performed by moving the lens L21 toward the object side along the optical axis. .

Table 1 below shows the values of each item in the first example. Surface numbers 1 to 25 in Table 1 correspond to the optical surfaces m1 to m25 shown in FIG.

(Table 1)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 12.09387 0.03211 1.48749 70.32
2 0.59705 0.15821
3 2.25156 0.08486 1.79952 42.09
4 -3.24544 0.30446
* 5 0.86514 0.10321 1.77250 49.50
* 6 -17.65410 0.00459
7 4.96570 0.08028 1.77250 49.62
8 -1.64751 0.01835 1.51742 52.20
9 0.54484 0.14598
10 ∞ 0.11468 (Aperture S)
11 -0.58359 0.01835 1.69895 30.13
12 0.82891 0.13303 1.62299 58.12
13 -0.76626 0.01835
* 14 2.05192 0.08028 1.80139 45.45
15 -3.16897 D15 (variable)
* 16 1.41916 0.15367 1.58913 61.25
17 -5.78117 D17 (variable)
18 -19.17738 0.10512 1.77250 49.62
19 -1.66077 0.22936
20 -0.78736 0.03211 1.48749 70.32
21 11.90217 0.02752
22 ∞ 0.01147 1.51680 64.20
23 ∞ 0.06422
24 ∞ 0.01606 1.51680 64.20
25 ∞ 0.01376
Image plane ∞

[Aspherical data]
5th surface κ = 1.0000, A4 = -3.89844E-01, A6 = -1.01196E + 00, A8 = -8.51346E-01, A10 = 0.00000E + 00
6th surface κ = 1.0000, A4 = -8.41827E-01, A6 = 0.00000E + 00, A8 = 0.00000E + 00, A10 = 0.00000E + 00
14th surface κ = 1.0000, A4 = -8.68270E-02, A6 = 5.31855E-02, A8 = 0.00000E + 00, A10 = 0.00000E + 00
16th surface κ = 1.0000, A4 = -1.37596E-01, A6 = 2.43999E-01, A8 = 1.09510E-01, A10 = 0.00000E + 00

[Overall specifications]
f 1.00
Fno 1.88
ω 26.41
Y 0.495
BF 0.133
BF (air equivalent) 0.124
TL 2.683
TL (Air conversion) 2.674

[Variable interval data]
Infinite state β = -1 / 20
D15 0.6417 0.5439
D17 0.0917 0.1896

[Lens group data]
Group number Group first surface Group focal length
G1 1 1.622
G2 16 2.280

[Conditional expression]
Conditional expression (1) TL / Σd = 1.048
Conditional expression (2) βR = 0.617
Conditional expression (3) {1- (βR1) ² } × (βRr) ² × 10 = 4.823
Conditional expression (4) GLd / TL = 0.229
Conditional expression (5) fF / f = 1.622
Conditional expression (6) fL / f = 2.280
Conditional expression (7) d / TL = 0.240
Conditional expression (8) GFd / TL = 0.485

From Table 1, it can be seen that the lens system IF1 according to the first example satisfies the conditional expressions (1) to (8).

FIG. 2 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma aberration diagram, and chromatic aberration diagram of magnification) of the lens system IF1 according to the first example, and (a) is infinite focus. The state (b) shows the short-distance in-focus state (shooting magnification β = −1 / 20).

In each aberration diagram, FNO is an F number, A is a half angle of view (unit: °) with respect to each image height, N
A represents the numerical aperture, and H0 represents the object height. Further, d indicates the d-line, g indicates the g-line, C indicates the C-line, and F indicates the aberration on the F-line. Those without these descriptions show aberrations at the d-line. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. In the coma aberration diagram, the solid line indicates the meridional coma. The lateral chromatic aberration diagram is based on the d-line. Note that the same reference numerals as in this embodiment are used in the aberration diagrams of each embodiment described later.

From the respective aberration diagrams shown in FIG. 2, it can be seen that the lens system IF1 according to the first example has various aberrations corrected well and has excellent imaging performance.

The lens system IF1 according to the first example includes a biconvex lens L constituting the first lens group G1.
An anti-vibration lens group VR that corrects image blur by moving 18 so as to have a component perpendicular to the optical axis.
Is possible.

(Second embodiment)
The second embodiment will be described with reference to FIGS. 3 and 4 and Table 2. FIG. As shown in FIG. 3, the lens system IF (IF2) according to the second example includes a first lens group G1 having a positive refractive power arranged in order from the object side along the optical axis, and a positive refractive power. And a second lens group G2 (corresponding to the lens group GL closest to the image plane in claim 1).

The first lens group G1 includes, in order from the object side along the optical axis, a positive meniscus lens L11 having a convex surface directed toward the object side, a positive meniscus lens L12 having a convex surface directed toward the image surface side, and a biconcave lens L13.
And a biconcave lens L14 and a biconvex lens L15, and a biconvex lens L16.

The second lens group G2 includes, in order from the object side along the optical axis, a biconvex lens L21, a biconvex lens L22, and a biconcave lens L23. The biconvex lens L21 has an aspheric object side surface.

An aperture stop S for determining brightness is disposed between the biconcave lens L13 and the biconcave lens L14 constituting the first lens group G1.

A filter group FL is disposed between the second lens group G2 and the image plane I. Filter group F
L is composed of a glass block such as a low-pass filter or an infrared cut filter for cutting a spatial frequency equal to or higher than the limit resolution of the solid-state imaging device, such as a CCD disposed on the image plane I.

In the lens system IF2 according to the present embodiment, the lens L21 constituting the second lens group G2 is used as a focusing lens group, and focusing from an infinite distance to a short distance object is performed by moving the lens L21 toward the object side along the optical axis. .

Table 2 below shows the values of each item in the second embodiment. Surface numbers 1 to 21 in Table 2 correspond to the optical surfaces m1 to m21 shown in FIG.

(Table 2)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 0.56176 0.08732 1.83481 42.73
2 6.86900 0.0328
3 -2.80256 0.03873 1.77250 49.62
4 -0.95226 0.01368 1.51742 52.20
5 0.38607 0.18095
6 ∞ 0.13675 (Aperture S)
7 -0.45946 0.01368 1.67270 32.18
8 0.66966 0.09915 1.62299 58.12
9 -0.59837 0.01368
10 1.99931 0.05983 1.75501 51.16
11 -1.85080 D11 (variable)
* 12 1.94573 0.11453 1.62263 58.16
13 -2.05739 D13 (variable)
14 4.58452 0.10318 1.77250 49.62
15 -1.47176 0.19932
16 -0.65602 0.02393 1.51742 52.20
17 3.10503 0.03077
18 ∞ 0.00855 1.51680 64.20
19 ∞ 0.04786
20 ∞ 0.01197 1.51680 64.20
21 ∞ 0.01026
Image plane ∞

[Aspherical data]
12th surface κ = 1.0000, A4 = -1.17346E-01, A6 = 7.34805E-01, A8 = -2.57206E + 00, A10 = 5.48603E + 00

[Overall specifications]
f 1.00
Fno 2.08
ω 20.27
Y 0.369
BF 0.109
BF (Air conversion) 0.102
TL 1.880
TL (air equivalent) 1.873

[Variable interval data]
Infinite state β = -1 / 20
D11 0.5851 0.4765
D13 0.0684 0.1769

[Lens group data]
Group number Group first surface Group focal length
G1 1 1.763
G2 12 1.590

[Conditional expression]
Conditional expression (1) TL / Σd = 1.058
Conditional expression (2) βR = 0.567
Conditional expression (3) {1- (βR1) ² } × (βRr) ² × 10 = 4.279
Conditional expression (4) GLd / TL = 0.272
Conditional expression (5) fF / f = 1.763
Conditional expression (6) fL / f = 1.590
Conditional expression (7) d / TL = 0.312
Conditional expression (8) GFd / TL = 0.361

From Table 2, it can be seen that the lens system IF2 according to the second example satisfies the conditional expressions (1) to (8).

FIG. 4 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion aberration diagram, coma aberration diagram and chromatic aberration diagram of magnification) of the lens system IF2 according to the second example, and (a) is infinite focus. The state (b) shows the short-distance in-focus state (shooting magnification β = −1 / 20).

From the aberration diagrams shown in FIG. 4, it can be seen that the lens system IF2 according to Example 2 has various aberrations corrected well and has excellent imaging performance.

The lens system IF2 according to the second example includes a biconvex lens L constituting the first lens group G1.
16 is moved so as to have a component in a direction perpendicular to the optical axis, and an image stabilizing lens group VR for correcting image blurring.
Is possible.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 5 and 6 and Table 3. FIG. As shown in FIG. 5, the lens system IF (IF3) according to the third example includes a first lens group G1 having a positive refractive power and arranged in order from the object side along the optical axis, and a positive refractive power. And a second lens group G2 (corresponding to the lens group GL closest to the image plane in claim 1).

The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a concave surface facing the image surface side, a biconvex lens L12, and a positive meniscus lens L1 having a convex surface facing the object side.
3, a cemented lens of a biconvex lens L14 and a biconcave lens L15, a cemented lens of a biconcave lens L16 and a biconvex lens L17, and a biconvex lens L18. In the positive meniscus lens L13, both the object side surface and the image side surface are aspherical surfaces. The biconvex lens L18 has an aspheric object side surface.

The second lens group G2 includes, in order from the object side along the optical axis, a biconvex lens L21, a positive meniscus lens L22 having a convex surface directed toward the image plane side, and a biconcave lens L23. The biconvex lens L21 has an aspheric object side surface.

An aperture stop S that determines the brightness is disposed between the biconcave lens L15 and the biconcave lens L16 constituting the first lens group G1.

A filter group FL is disposed between the second lens group G2 and the image plane I. Filter group F
L is composed of a glass block such as a low-pass filter or an infrared cut filter for cutting a spatial frequency equal to or higher than the limit resolution of the solid-state imaging device, such as a CCD disposed on the image plane I.

In the lens system IF3 according to the present embodiment, the lens L21 constituting the second lens group G2 is used as a focusing lens group, and focusing from an infinite distance to a short distance object is performed by moving the lens L21 toward the object side along the optical axis. .

Table 3 below shows values of various specifications in the third example. Surface numbers 1 to 25 in Table 3 correspond to the optical surfaces m1 to m25 shown in FIG.

(Table 3)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 7.72079 0.03883 1.48749 70.32
2 0.73505 0.24965
3 7.97609 0.09709 1.79952 42.09
4 -3.86132 0.44679
* 5 1.07514 0.11096 1.77250 49.50
* 6 13.40308 0.00973
7 1.57699 0.11096 1.77250 49.62
8 -3.94513 0.02219 1.51742 52.20
9 0.65481 0.14117
10 ∞ 0.22191 (Aperture S)
11 -0.70719 0.02219 1.69895 30.13
12 0.81778 0.15257 1.62299 58.12
13 -1.03994 0.02219
* 14 2.01849 0.09709 1.80139 45.45
15 -3.59054 D15 (variable)
* 16 1.99295 0.16089 1.58913 61.25
17 -3.68666 D17 (variable)
18 -32.50277 0.11952 1.77250 49.62
19 -1.93781 0.27739
20 -0.83101 0.03883 1.48749 70.32
21 10.79972 0.03329
22 ∞ 0.01387 1.51680 64.20
23 ∞ 0.07767
24 ∞ 0.01942 1.51680 64.20
25 ∞ 0.01664
Image plane ∞

[Aspherical data]
5th surface κ = 1.0000, A4 = -2.11671E-01, A6 = -2.62939E-01, A8 = 7.39402E-02, A10 = 0.00000E + 00
6th surface κ = 1.0000, A4 = -3.98901E-01, A6 = 0.00000E + 00, A8 = 0.00000E + 00, A10 = 0.00000E + 00
14th surface κ = 1.0000, A4 = -7.98230E-02, A6 = 4.31495E-02, A8 = 0.00000E + 00, A10 = 0.00000E + 00
16th surface κ = 1.0000, A4 = -1.18657E-01, A6 = 1.91854E-01, A8 = 8.83352E-02, A10 = 0.00000E + 00

[Overall specifications]
f 1.00
Fno 1.88
ω 31.44
Y 0.599
BF 0.161
BF (Air conversion) 0.150
TL 3.135
TL (air equivalent) 3.123

[Variable interval data]
Infinite state β = -1 / 20
D15 0.5227 0.4262
D17 0.1110 0.2075

[Lens group data]
Group number Group first surface Group focal length
G1 1 1.640
G2 16 2.787

[Conditional expression]
Conditional expression (1) TL / Σd = 1.050
Conditional expression (2) βR = 0.610
Conditional expression (3) {1- (βR1) ² } × (βRr) ² × 10 = 4.930
Conditional expression (4) GLd / TL = 0.227
Conditional expression (5) fF / f = 1.640
Conditional expression (6) fL / f = 2.787
Conditional expression (7) d / TL = 0.167
Conditional expression (8) GFd / TL = 0.558

From Table 3, it can be seen that the lens system IF3 according to the third example satisfies the conditional expressions (1) to (8).

FIG. 6 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma aberration diagram and chromatic aberration diagram of magnification) of the lens system IF3 according to the third example, and (a) is infinite focus. The state (b) shows the short-distance in-focus state (shooting magnification β = −1 / 20).

From the aberration diagrams shown in FIG. 6, it can be seen that the lens system IF3 according to the third example has various aberrations corrected well and has excellent imaging performance.

In the lens system IF3 according to the third example, the biconvex lens L constituting the first lens group G1 is used.
An anti-vibration lens group VR that corrects image blur by moving 18 so as to have a component perpendicular to the optical axis.
Is possible.

(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. As shown in FIG. 7, the lens system IF (IF4) according to the fourth example includes a first lens group G1 having negative refractive power arranged in order from the object side along the optical axis, and a positive refractive index. And a third lens group G3 having a positive refractive power (corresponding to the lens group GL closest to the image plane in claim 1).

The first lens group G1 includes, in order from the object side along the optical axis, a negative meniscus lens L11 having a concave surface directed toward the image surface side, and a biconvex lens L12.

The second lens group G2 includes, in order from the object side along the optical axis, a biconvex lens L21, a cemented lens of a positive meniscus lens L22 having a convex surface facing the image surface side and a biconcave lens L23, a biconcave lens L24, and a biconvex lens. It consists of a cemented lens with L25 and a biconvex lens L26. In the biconvex lens L21, both the object side surface and the image side surface are aspherical surfaces. The biconvex lens L26 has an aspheric object side surface.

The third lens group G3 includes, in order from the object side along the optical axis, a cemented lens of a biconvex lens L31 and a negative meniscus lens L32 having a concave surface facing the object side, and a positive meniscus lens L33 having a convex surface facing the image surface side. A positive meniscus lens L34 having a convex surface facing the image surface side, and a biconcave lens L3
5.

An aperture stop S that determines the brightness is disposed between the biconcave lens L23 and the biconcave lens L24 that form the second lens group G2.

A filter group FL is disposed between the third lens group G3 and the image plane I. Filter group F
L is composed of a glass block such as a low-pass filter or an infrared cut filter for cutting a spatial frequency equal to or higher than the limit resolution of the solid-state imaging device, such as a CCD disposed on the image plane I.

Focusing of the lens system IF4 according to the present embodiment includes focusing in the normal mode and focusing in the macro mode. In the normal mode, by moving the cemented lens including the lenses L31 and L32 constituting the third lens group G3 as the focusing lens group toward the object side along the optical axis,
Focus from infinity to a close object. In macro mode, the normal mode
Lens group G1 (lenses L11 and L12) and second lens group G2 (lenses L21 to L26)
Are separately moved to the object side along the optical axis to perform focusing on a certain finite distance, and from this state, a cemented lens composed of the lenses L31 and L32 constituting the third lens group G3 is formed. By moving to the object side along the optical axis, focusing in the macro area is performed.

Table 4 below shows values of various specifications in the fourth embodiment. Surface numbers 1 to 28 in Table 4 correspond to the optical surfaces m1 to m28 shown in FIG.

(Table 4)
[Lens specifications]
Surface number R D nd νd
Object ∞
1 2.04919 0.03211 1.48749 70.32
2 0.51948 0.20642
3 2.14272 0.07798 1.79952 42.09
4 -4.92994 D4 (variable)
* 5 1.01124 0.12156 1.77250 49.50
* 6 -2.22421 0.02444
7 -7.91350 0.06422 1.48749 70.32
8 -0.92730 0.01835 1.51742 52.20
9 0.54488 0.09499
10 ∞ 0.18349 (Aperture S)
11 -0.54833 0.01835 1.69895 30.13
12 1.69351 0.13761 1.62299 58.12
13 -0.56457 0.01835
* 14 1.70802 0.08028 1.80139 45.45
15 -6.05114 D15 (variable)
16 2.44808 0.15367 1.51680 63.88
17 -1.67557 0.02752 1.62004 36.40
18 -3.72050 D18 (variable)
19 -7.48022 0.06422 1.77250 49.62
20 -2.41344 0.00459
21 -8.11118 0.06078 1.77250 49.62
22 -2.47422 0.25955
23 -0.93140 0.03211 1.48749 70.32
24 11.90217 0.02752
25 ∞ 0.01147 1.51680 64.20
26 ∞ 0.06422
27 ∞ 0.01606 1.516798 64.2
28 ∞ 0.01376
Image plane ∞

[Aspherical data]
5th surface κ = 1.0000, A4 = -2.84942E-01, A6 = -1.23777E + 00, A8 = 1.22949E-01, A10 = 0.00000E + 00
6th surface κ = 1.0000, A4 = -7.07314E-01, A6 = 0.00000E + 00, A8 = 0.00000E + 00, A10 = 0.00000E + 00
14th surface κ = 1.0000, A4 = -1.09556E-01, A6 = 4.25805E-01, A8 = -6.34260E-01, A10 = 0.00000E + 00

[Overall specifications]
f 1.00
Fno 2.00
ω 26.80
Y 0.495
BF 0.133
BF (air equivalent) 0.124
TL 2.752
TL (air equivalent) 2.743

[Variable interval data]
Normal mode Macro mode Infinite state β = -1 / 20 β = -1 / 20 β = -1 / 7.7
D4 0.26340 0.26340 0.26887 0.26887
D15 0.59040 0.44580 0.69389 0.46075
D18 0.08486 0.22941 0.08486 0.31800

[Lens group data]
Group number Group first surface Group focal length
G1 1 -11.826
G2 5 1.564
G3 16 3.340

[Conditional expression]
Conditional expression (1) TL / Σd = 1.047
Conditional expression (2) βR = 0.695
Conditional expression (3) {1- (βR1) ² } × (βRr) ² × 10 = 3.178
Conditional expression (4) GLd / TL = 0.251
Conditional expression (5) fF / f = 1.440
Conditional expression (6) fL / f = 3.340
Conditional expression (7) d / TL = 0.215
Conditional expression (8) GFd / TL = 0.489

From Table 4, it can be seen that the lens system IF4 according to Example 4 satisfies the conditional expressions (1) to (8).

FIG. 8 is a diagram showing various aberrations (spherical aberration diagram, astigmatism diagram, distortion diagram, coma aberration diagram, and chromatic aberration diagram of magnification) in the normal mode of the lens system IF4 according to Example 4, wherein (a) is infinite. The far focus state, (b) shows the short distance focus state (imaging magnification β = −1 / 20), respectively. FIG. 9 is a diagram of various aberrations (spherical aberration diagram, astigmatism diagram) in the macro mode of the lens system IF4 according to Example 4.
(A) is a state in which the photographing magnification is β = −1 / 20, and (b) is a state in which the photographing magnification is β = −1 / 7.7. Respectively.

From the aberration diagrams shown in FIGS. 8 and 9, it can be seen that the lens system IF4 according to the fourth example has various aberrations corrected well and has excellent imaging performance.

The lens system IF4 according to the fourth example includes a biconvex lens L constituting the second lens group G2.
An anti-vibration lens group VR that corrects image blur by moving the lens 26 so as to have a component perpendicular to the optical axis.
Is possible.

According to each of the embodiments described above, it is possible to provide a lens system that is small and has good optical performance.

In order to make the present invention easy to understand so far, the configuration requirements of the embodiment have been described.
It goes without saying that the present invention is not limited to this. The following contents can be appropriately adopted as long as the optical performance of the lens system IF of the present application is not impaired.

As a numerical example of the lens system IF according to the present embodiment, a two-group, three-group configuration is shown, but the present invention is not limited to this, and the present invention is also applicable to other group configurations (for example, the fourth group, the fifth group, etc.). Is possible. Specifically, a configuration in which a lens or a lens group is added closest to the object side or a configuration in which a lens or a lens group is added closest to the image side may be used. The lens group indicates a portion having at least one lens separated by an air interval that changes at the time of zooming or focusing.

In the lens system IF according to the present embodiment, in order to perform focusing from infinity to a short distance object, a part of the lens group, one entire lens group, or a plurality of lens groups as a focusing lens group,
It is good also as a structure moved to an optical axis direction. This focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like). In particular, it is preferable that at least a part of the lens group closest to the image plane is a focusing lens group.

In the lens system IF according to the present embodiment, either the entire lens group or the partial lens group is moved so as to have a component in a direction perpendicular to the optical axis, or rotated in an in-plane direction including the optical axis ( The image stabilizing lens group may be configured to correct image blur caused by camera shake or the like. In particular, it is preferable that at least a part of the lens group adjacent to the object side of the lens group closest to the image plane is an anti-vibration lens group.

In the lens system IF according to the present embodiment, the lens surface may be formed as a spherical surface or a flat surface, or may be formed as an aspheric surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and optical performance deterioration due to errors in processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is an aspheric surface, the aspheric surface is an aspheric surface by grinding, a glass mold aspheric surface made of glass with an aspheric shape, or a composite aspheric surface made of resin with an aspheric shape on the glass surface. Any aspherical surface may be used. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

In the lens system IF according to the present embodiment, it is preferable that the aperture stop S is disposed closer to the object side than the lens group closest to the image plane side. A role may be substituted.

In the lens system IF according to the present embodiment, each lens surface may be provided with an antireflection film having high transmittance in a wide wavelength region in order to reduce flare and ghost and achieve high optical performance with high contrast. .

IF (IF1 to IF4) Lens system G1 First lens group G2 Second lens group G3 Third lens group GL Lens group closest to the image plane S Aperture stop FL filter I Image plane 1 Camera (optical equipment)

Claims (17)

Having at least two lens groups;
The lens group closest to the image plane has a biconvex positive lens component, a positive lens, and a biconcave negative lens arranged closest to the image plane, arranged in order from the object side.
Focusing is performed by moving the biconvex positive lens component constituting the most image side lens group in the optical axis direction as a focusing lens group,
A lens system characterized by satisfying the following conditional expression:
TL / Σd <1.10
However,
TL: full length of the lens system (distance from the lens frontmost surface to the image plane on the optical axis),
Σd: Distance from the foremost lens surface to the last lens surface on the optical axis. The lens system according to claim 1, wherein the following conditional expression is satisfied.
0.55 <βR <0.95
However,
βR: lateral magnification of the lens group closest to the image plane. The lens system according to claim 1, wherein the following conditional expression is satisfied.
2.00 <{1- (βR1) ² } × (βRr) ² × 10 <6.00
However,
βR1: lateral magnification of the biconvex positive lens component of the lens group closest to the image plane,
βRr: the combined lateral magnification of the lens disposed on the image plane side with respect to the biconvex positive lens component of the lens group closest to the image plane. The lens system according to claim 1, wherein the following conditional expression is satisfied.
GLd / TL <0.30
However,
GLd: the thickness on the optical axis of the lens unit closest to the image plane. The lens system according to claim 1, wherein the following conditional expression is satisfied.
0.50 <fF / f <10.00
However,
fF: the combined focal length of the lens unit disposed closer to the object side than the lens unit closest to the image plane side,
f: Focal length of the entire lens system. The lens system according to claim 1, wherein the following conditional expression is satisfied.
1.00 <fL / f <4.00
However,
fL: focal length of the lens unit closest to the image plane,
f: Focal length of the entire lens system. The lens system according to claim 1, wherein the following conditional expression is satisfied.
0.15 <d / TL <0.50
However,
d: Distance from the last surface of the lens group adjacent to the object side of the lens unit closest to the image plane on the optical axis to the forefront surface of the lens group closest to the image plane. At least a part of the lens unit disposed on the object side of the lens unit closest to the image plane is movable as a vibration-proof lens unit so as to have a component perpendicular to the optical axis in order to correct image blurring. The lens system according to claim 1, wherein the lens system is configured. 9. The image stabilizing lens group according to claim 8, wherein the image stabilizing lens group is a lens disposed closest to the image plane in a lens group disposed closer to the object side than the lens group closest to the image plane. Lens system. 10. The lens system according to claim 8, wherein the anti-vibration lens group is any single lens in a lens group disposed closer to the object side than the lens group closest to the image plane. The lens system according to claim 1, wherein the following conditional expression is satisfied.
0.30 <GFd / TL
However,
GFd: the thickness on the optical axis of the lens unit disposed closer to the object side than the lens unit closest to the image plane. The lens group adjacent to the object side with respect to the lens group closest to the image plane includes at least one positive lens and one negative lens. The lens system described in 1. The lens system according to any one of claims 1 to 12, wherein the lens group adjacent to the object side relative to the lens group closest to the image plane includes at least one cemented lens. The lens system according to claim 1, wherein the aperture stop is disposed closer to the object side than the lens group closest to the image plane. The lens system according to any one of claims 1 to 14, wherein an aperture stop is disposed in a lens group adjacent to the object side of the lens group closest to the image plane. An optical apparatus comprising the lens system according to any one of claims 1 to 15. A method of manufacturing a lens system having at least two lens groups,
The lens group closest to the image plane has a biconvex positive lens component, a positive lens, and a biconcave negative lens arranged closest to the image plane, arranged in order from the object side.
Focusing is performed by moving the biconvex positive lens component constituting the most image side lens group in the optical axis direction as a focusing lens group,
To satisfy the following conditional expression,
A lens system manufacturing method, wherein each lens is disposed in a lens barrel.
TL / Σd <1.10
However,
TL: full length of the lens system (distance from the lens frontmost surface to the image plane on the optical axis),
Σd: Distance from the foremost lens surface to the last lens surface on the optical axis.

Images