JP2023074094A - Optical system - Google Patents

Abstract

To provide an optical system in which glass material of lenses constituting each group are appropriately selected and disposed, and which therefore corrects various aberrations such as a chromatic aberration and furthermore achieves shortening of an entire length and diameter and reduction in weight of the optical system, and consequently has high-performance focus.SOLUTION: An optical system is comprised of, in order from an object side,: a first lens group G1 having negative refractive power; a second lens group G2 refractive power; a third lens group G3 having positive refractive power; a fourth lens group G4 having refractive power; and a fifth lens group G5 having refractive power, wherein upon focusing, at least the second lens group moves along an optical axis, an interval between the first lens group and second lens group varies, an interval between the second lens group and third lens group varies, the fourth lens group includes a lens having the positive refractive power and a lens having the negative refractive power, the fifth lens group includes a lens having the positive refractive power, and a lens having the negative refractive power, and has the lens having the refractive power or a doublet lens including the lens having the positive refractive power arranged on the most object side, and wherein the optical system satisfies a specific conditional expression.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical system suitable for lenses used in imaging devices such as still cameras and video cameras, projection devices, etc., and is appropriately arranged so as to contribute to weight reduction while effectively correcting chromatic aberration. be.

2. Description of the Related Art In recent years, with the increase in the number of pixels of digital cameras and the like, strict correction of various aberrations in the optical system used has been required.

Also, for high-speed and accurate focus drive and wobbling drive for contrast detection during autofocus, it is desired to reduce the weight of parts that move during focus drive.

Therefore, in optical systems that have been proposed in the past, it has been proposed that the group from the object side to the aperture stop is fixed during focus driving, and that the focus group is arranged on the image side of the stop, thereby reducing the weight of the focus group. was

International Publication 2019/073744 JP 2016-009170 A

Japanese Patent Application Laid-Open No. 2002-100003 proposes an optical system that is of the inner focus type and that suppresses various aberrations by appropriately designating the configuration of lens groups that move during focusing. However, the optical system described in Patent Document 1 tends to leave color flare due to the deviation of the image forming point in the optical axis direction from the C line to the F line from the intermediate angle of view to the periphery of the screen, and is also used in optical systems with a large aperture ratio. In this case, there is a problem that the weight of the driving part tends to be heavy.

Japanese Patent Application Laid-Open No. 2002-200001 proposes an optical system that has a large aperture ratio and reduces the weight of the lens that moves during focusing. However, the optical system described in Patent Document 2 does not sufficiently correct axial chromatic aberration and chromatic aberration of magnification in addition to chromatic flare, and there is a problem that sagittal coma flare tends to occur.

By appropriately selecting and arranging the glass materials of the lenses that make up each group, the present invention achieves a reduction in overall length and diameter, a reduction in weight, and a high-performance focus while correcting various aberrations such as chromatic aberration. The purpose is to provide an optical system.

A first invention, which is means for solving the above problems, comprises, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive or negative refractive power, and a positive a third lens group G3 having a refractive power of , a fourth lens group G4 having a positive or negative refractive power, and a fifth lens group G5 having a positive or negative refractive power. The second lens group G2 moves along the optical axis, and at the same time the distance between the first lens group G1 and the second lens group G2 changes, and at the same time the second lens group G2 and the third lens group G3 move. The fourth lens group G4 includes a lens with positive refractive power and a lens with negative refractive power, and the fifth lens group G5 includes a lens with positive refractive power and a lens with negative refractive power. and a lens having positive refracting power or a cemented lens including a lens having positive refracting power is disposed closest to the object side of the fifth lens group G5, and from conditional expression (1) below ( 4) is satisfied.
(1) ΔθgF_G4P > 0.000
(2) VD_GF4P > 50.00
(3) ΔθgF_G5P > 0.000
(4) VD_GF5P < 40.00
however,
ΔθgF_G4P: Average value of the deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line of the lenses having positive refractive power constituting the fourth lens group G4 The deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line ΔθgF=θgF−(0.648285−0.00180123×VD) where θgF is the partial dispersion ratio for the g-line and F-line, and VD is the Abbe number at the d-line.
VD_GF4P calculated as: average value of Abbe numbers at the d-line of the lenses having positive refractive power that constitute the fourth lens group G4 ΔθgF_G5P: of the lenses having positive refractive power that constitute the fifth lens group G5 Average value VD_GF5P of partial dispersion ratio deviation ΔθgF for g-line and F-line: average value of Abbe numbers for d-line of lenses having positive refractive power that constitute the fifth lens group G5

A second invention is an optical system according to the first invention, wherein the groups other than the second lens group G2 are fixed with respect to the image plane during focusing.

A third invention is an optical system according to the first or second invention, characterized by further satisfying the following conditional expression.
(5) -1.50 < f/f1 < 0.00
(6) 0.05<f/|f2|<0.75
(7) 0.10 < f/f3 < 1.20
(8) -1.00 < f/f4 < 1.00
(9) -1.00 < f/f5 < 1.00
however,
f: focal length of the entire lens system when photographing at infinity f1: focal length of the first lens group G1 when photographing at infinity f2: photographing at infinity focal length f3 of the second lens group G2 at time: focal length f4 of the third lens group G3 at infinity photography: focal length f5 of the fourth lens group G4 at infinity photography: focal length f5 of the fourth lens group G4 at infinity photography Focal length of the fifth lens group G5

A fourth invention is an optical system according to any one of the first to third inventions, characterized by further satisfying the following conditional expression.
(10) VD_G1P < 40.00
(11) ΔθgF_G1N>−0.010
(12) ΔθgF_G3P>−0.005
(13) ΔθgF_G4N < 0.010
(14) ΔθgF_G5N < 0.005
(15) nd_G1P > 1.8500
(16) nd_G5P > 1.8500
however,
VD_G1P: Average value ΔθgF_G1N of the Abbe number at the d-line of the lenses having positive refractive power that constitute the first lens group G1: g-line and F of the lenses having negative refractive power that constitute the first lens group G1 Average value ΔθgF_G3P of the deviation ΔθgF of the partial dispersion ratio with respect to the line: Average value ΔθgF_G4N of the deviation ΔθgF of the partial dispersion ratio with respect to the g-line and the F-line of the lenses having positive refractive power constituting the third lens group G3: The fourth Average value ΔθgF_G5N of the deviation ΔθgF of the partial dispersion ratio for the g-line and F-line of the lenses having negative refractive power forming the lens group G4: the g-line of the lenses having negative refractive power forming the fifth lens group G5 and the deviation ΔθgF of the partial dispersion ratio with respect to the F-line nd_G1P: the average value of the refractive indices for the d-line of the lenses having positive refractive power constituting the first lens group G1 nd_G5P: constituting the fifth lens group G5 the average value of the refractive index at the d-line of a lens with positive refractive power

In a fifth invention, in any one of the first to fourth inventions, the first lens group G1 further comprises a negative refractive power meniscus lens with a convex surface facing from the object side to the object side, An optical system characterized by including a configuration in which a lens of negative refractive power and a lens of positive refractive power are arranged in order.

In a sixth aspect of the invention, in any one of the first to fifth aspects, the cemented surface of the fourth lens group G4 has a convex surface facing the object side, and the refractive index of the medium on the object side is This optical system is characterized by having one or more sets of cemented lenses having a refractive index higher than that of a medium on the image plane side.

In a seventh invention, in any one of the first to sixth inventions, the positive refractive power of the fifth lens group G5 weakens from the center of the optical axis toward the periphery, or the negative refractive power An optical system characterized by having a strong aspherical surface.

An eighth invention is an optical system according to any one of the first to seventh inventions, wherein the second lens group G2 is further composed of two or less lenses.

According to the present invention, by appropriately selecting and arranging the glass materials of the lenses that make up each group, it is possible to correct various aberrations such as chromatic aberration, reduce the overall length and diameter, and reduce the weight, thereby achieving high-performance focusing. can be provided.

Lens cross-sectional view of the optical system of Example 1 at infinity Longitudinal aberration diagram of the optical system of Example 1 at infinity Longitudinal aberration diagram of the optical system of Example 1 at a shooting distance of 249 mm Lateral aberration diagram of the optical system of Example 1 at infinity Lateral aberration diagram of the optical system of Example 1 at a shooting distance of 249 mm Lens sectional view of the optical system of Example 2 at infinity Longitudinal aberration diagram of the optical system of Example 2 at infinity Longitudinal aberration diagram of the optical system of Example 2 at a shooting distance of 250 mm Lateral aberration diagram of the optical system of Example 2 at infinity Lateral aberration diagram of the optical system of Example 2 at a shooting distance of 250 mm Lens sectional view at infinity of the optical system of Example 3 Longitudinal aberration diagram of the optical system of Example 3 at infinity Longitudinal aberration diagram of the optical system of Example 3 at a shooting distance of 248 mm Lateral aberration diagram of the optical system of Example 3 at infinity Lateral aberration diagram of the optical system of Example 3 at a shooting distance of 248 mm Lens sectional view at infinity of the optical system of Example 4 Longitudinal aberration diagram of the optical system of Example 4 at infinity Longitudinal aberration diagram of the optical system of Example 4 at a shooting distance of 245 mm Lateral aberration diagram of the optical system of Example 4 at infinity Lateral aberration diagram of the optical system of Example 4 at a shooting distance of 245 mm Cross-sectional view of lenses at infinity at the wide-angle end of the variable-magnification optical system of Example 5 Longitudinal aberration diagram at infinity at the wide-angle end of the variable power optical system of Example 5 Longitudinal aberration diagram at infinity of the intermediate focal length of the variable magnification optical system of Example 5 Longitudinal aberration diagram at infinity at the telephoto end of the variable magnification optical system of Example 5 Lateral aberration diagram at infinity at the wide-angle end of the variable power optical system of Example 5 Lateral Aberration Diagram at Infinity at Intermediate Focal Length of the Magnifying Optical System of Example 5 Lateral aberration diagram at infinity at the telephoto end of the variable power optical system of Example 5 Lens sectional view at infinity of the optical system of Example 6 Longitudinal aberration diagram at infinity of the optical system of Example 6 Longitudinal aberration diagram of the optical system of Example 6 at a shooting distance of 226 mm Lateral aberration diagram of the optical system of Example 6 at infinity Lateral aberration diagram of the optical system of Example 6 at a shooting distance of 226 mm Lens sectional view at infinity of the optical system of Example 7 Longitudinal aberration diagram of the optical system of Example 7 at infinity Longitudinal aberration diagram of the optical system of Example 7 at a shooting distance of 227 mm Lateral aberration diagram of the optical system of Example 7 at infinity Lateral aberration diagram of the optical system of Example 7 at a shooting distance of 227 mm Lens sectional view at infinity of the optical system of Example 8 Longitudinal aberration diagram of the optical system of Example 8 at infinity Longitudinal aberration diagram of the optical system of Example 8 at a shooting distance of 225 mm Lateral aberration diagram of the optical system of Example 8 at infinity Lateral aberration diagram of the optical system of Example 8 at a shooting distance of 225 mm

Examples of the optical system according to the present invention will be described in detail below. It should be noted that the following description of the embodiment is an example of the optical system of the present invention, and the present invention is not limited to the present embodiment without departing from the scope of the invention.

In the specification of this application, when the number of lenses is counted, a single lens is counted as one lens, and a cemented lens is counted as one lens for each single lens constituting the cemented lens, unless otherwise specified. For example, a cemented lens consisting of a convex lens and a concave lens is counted as two lenses.

As can be seen from the lens configuration diagrams shown in FIGS. 1, 6, 11, 16, 21, 28, 33 and 38, the optical system of the present invention has negative refractive power in order from the object side. a first lens group G1 having positive or negative refractive power, a second lens group G2 having positive or negative refractive power, a third lens group G3 having positive refractive power, and a fourth lens group G4 having positive or negative refractive power , and a fifth lens group G5 having a positive or negative refractive power. At least the second lens group G2 moves along the optical axis during focusing, and at the same time the first lens group G1 and the second lens group G2 move along the optical axis. The distance from the lens group G2 changes, the distance between the second lens group G2 and the third lens group G3 changes at the same time, and the fourth lens group G4 has a lens with positive refractive power and a lens with negative refractive power. The fifth lens group G5 includes a lens having positive refractive power and a lens having negative refractive power, and a lens having positive refractive power closest to the object side of the fifth lens group G5 or It is characterized by arranging a cemented lens including a lens having a positive refractive power.

An object of the present invention is to provide an optical system that achieves miniaturization while correcting various aberrations such as chromatic aberration, and it is important to appropriately select glass materials for lenses constituting each lens group.

Especially in wide-angle to standard optical systems, as a means of simultaneously correcting longitudinal chromatic aberration and lateral chromatic aberration, the wavelength dispersion of the refractive index is small on the image plane side of the stop, and the wavelength dispersion on the short wavelength side near the g-line is small. It is known to apply a glass material having a large anomalous dispersion to a lens having a positive refractive power. However, since many of such glass materials have a low refractive index, they are disadvantageous in controlling curvature of field. Moreover, even if axial chromatic aberration and lateral chromatic aberration can be corrected, it is difficult to correct flare due to short-wavelength rays around the screen.

Therefore, the lens group on the image plane side of the diaphragm is divided into a fourth lens group G4 on the object side and a fifth lens group G5 on the image plane side, and a lens having a positive refractive power and a lens having a negative refractive power are provided in each group. By arranging lenses with positive refractive power and appropriately setting the dispersion characteristics of each lens with positive refractive power, axial chromatic aberration, chromatic aberration of magnification, and flare at the periphery of the screen can be corrected at the same time, while also suppressing curvature of field. becomes possible.

In addition, by arranging the first lens group G1, the second lens group G2, and the third lens group G3 in this order from the object side closest to the object side of the stop, and setting the second lens group G2 as a group to be driven during focusing, There is no need to secure a space for focusing on the diaphragm image plane side, and the ability to correct the above-described chromatic aberration can be maximized.

Further, the optical system of the present invention is characterized by satisfying the following conditional expressions.
(1) ΔθgF_G4P > 0.000
(2) VD_GF4P > 50.00
(3) ΔθgF_G5P > 0.000
(4) VD_GF5P < 40.00
ΔθgF_G4P: Average value of the deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line of the lenses having positive refractive power constituting the fourth lens group G4 The deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line ΔθgF=θgF−(0.648285−0.00180123×VD) where θgF is the partial dispersion ratio for the g-line and F-line, and VD is the Abbe number at the d-line.
VD_GF4P calculated as: average value of Abbe numbers at the d-line of the lenses having positive refractive power that constitute the fourth lens group G4 ΔθgF_G5P: of the lenses having positive refractive power that constitute the fifth lens group G5 Average value VD_GF5P of partial dispersion ratio deviation ΔθgF for g-line and F-line: Calculated as an average value of Abbe numbers for the d-line of the lenses having positive refractive power constituting the fifth lens group G5.

Conditional expression (1) defines a preferable range of the partial dispersion ratio for the g-line and the F-line of the lens having positive refractive power that constitutes the fourth lens group G4.

When the average value of the deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line of the lenses having positive refractive power constituting the fourth lens group G4 becomes smaller than the lower limit of conditional expression (1), the fourth It becomes difficult to correct longitudinal chromatic aberration in the lens group G4.

Conditional expression (2) defines a preferable range for the Abbe number at the d-line of the lens having positive refractive power that constitutes the fourth lens group G4.

When the average value of the Abbe numbers for the d-line of the lenses having positive refractive power constituting the fourth lens group G4 becomes smaller than the lower limit of conditional expression (2), the positive It becomes difficult to select a glass material with large anomalous dispersion on the short wavelength side near the g-line for a lens with a refractive power of It becomes difficult to correct color flare caused by

By setting the lower limit of conditional expression (2) to 55.00, the effect of the present invention can be achieved more reliably.

Conditional expression (3) defines a preferable range of the partial dispersion ratio for the g-line and the F-line of the lens having positive refractive power that constitutes the fifth lens group G5.

When the average value of the deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line of the lenses having positive refractive power constituting the fifth lens group G5 becomes smaller than the lower limit of conditional expression (3), the fifth It becomes difficult to correct the g-line chromatic aberration of magnification in the lens group G5.

Conditional expression (4) defines a preferable range for the Abbe number at the d-line of the lens having positive refractive power that constitutes the fifth lens group G5.

When the average value of the Abbe numbers for the d-line of the lenses having positive refractive power constituting the fifth lens group G5 exceeds the upper limit of conditional expression (4), the positive Since it becomes difficult to select a glass material with a large refractive index for a lens with a refractive power of , it becomes difficult to correct the field curvature. becomes difficult.

By setting the upper limit of conditional expression (4) to 35.00, the effect of the present invention can be achieved more reliably.

In the optical system of the present invention, it is desirable that the groups other than the second lens group G2 are fixed with respect to the image plane during focusing.

By fixing the groups other than the second lens group G2 with respect to the image plane during focusing, the mechanism for moving during focusing can be simplified and the weight can be reduced.

Further, the optical system of the present invention preferably satisfies the following conditional expressions.
(5) -1.50 < f/f1 < 0.00
(6) 0.05<f/|f2|<0.75
(7) 0.10 < f/f3 < 1.20
(8) -1.00 < f/f4 < 1.00
(9) -1.00 < f/f5 < 1.00
however,
f: focal length of the entire lens system when shooting at infinity f1: focal length at the telephoto end when the optical system is a zoom lens f1: focal length of the first lens group G1 when shooting at infinity f2: at shooting at infinity Focal length f3 of the second lens group G2: Focal length f4 of the third lens group G3 when shooting at infinity: Focal length f5 of the fourth lens group G4 when shooting at infinity: Focal length f5 of the fourth lens group G4 when shooting at infinity Focal length of 5 lens group G5

Conditional expression (5) defines a preferable range for the refractive power of the first lens group G1.

If the upper limit of conditional expression (5) is exceeded and the refractive power of the first lens group G1 becomes positive, it becomes difficult to secure a sufficiently wide angle of view.

When the lower limit of conditional expression (5) is exceeded and the negative refractive power of the first lens group G1 increases, the divergence of the exiting marginal light flux increases, and the diameter of the light flux passing through the second lens group G2 increases. This makes it difficult to reduce the weight of the parts that are driven during focusing.

By setting the lower limit of conditional expression (5) to −1.40, the effects of the present invention can be achieved more reliably. By setting the upper limit of conditional expression (5) to −0.05, the effects of the present invention can be achieved more reliably.

Conditional expression (6) defines a preferable range for the refractive power of the second lens group G2.

When the upper limit of conditional expression (6) is exceeded and the absolute value of the refractive power of the second lens group G2 increases, it becomes difficult to suppress deterioration of aberration due to the decentering of the second lens group G2. In addition, the focus position on the image plane side moves greatly with only a small amount of focus movement, making precise focusing difficult.

When the lower limit of conditional expression (6) is exceeded and the absolute value of the refracting power of the second lens group G2 becomes weak, the distance over which the second lens group G2 moves during focusing increases, resulting in faster focusing and It becomes difficult to shorten the total length.

By setting the lower limit of conditional expression (6) to 0.10, the effect of the present invention can be achieved more reliably. By setting the upper limit of conditional expression (6) to 0.60, the effect of the present invention can be achieved more reliably.

Conditional expression (7) defines a preferable range for the refractive power of the third lens group G3.

When the upper limit of conditional expression (7) is exceeded and the refractive power of the third lens group G3 becomes strong, it becomes difficult to suppress various aberrations such as spherical aberration within the group.

When the lower limit of conditional expression (7) is exceeded and the refractive power of the third lens group G3 becomes weak, the action of converging the light flux becomes weak. increases, making it difficult to reduce the weight of the parts that are driven during focusing and to control the outer diameter of the product.

By setting the lower limit of conditional expression (7) to 0.15, the effect of the present invention can be achieved more reliably. By setting the upper limit of conditional expression (7) to 1.00, the effect of the present invention can be achieved more reliably.

Conditional expression (8) defines a preferable range for the refractive power of the fourth lens group G4.

If the upper limit of conditional expression (8) is exceeded and the positive refractive power of the fourth lens group G4 becomes strong, it becomes difficult to suppress various aberrations such as coma, and in addition, the light incident on the fifth lens group G5 becomes difficult. As a result, the fifth lens group G5 cannot sufficiently exhibit the function of suppressing the chromatic aberration of magnification.

If the lower limit of conditional expression (8) is exceeded and the negative refractive power of the fourth lens group G4 becomes strong, the luminous flux expands, making it difficult to reduce the size in the radial direction.

By setting the lower limit of conditional expression (8) to −0.90, the effects of the present invention can be achieved more reliably. By setting the upper limit of conditional expression (8) to 0.90, the effect of the present invention can be achieved more reliably.

Conditional expression (9) defines a preferable range for the refractive power of the fifth lens group G5.

When the upper limit of conditional expression (9) is exceeded and the positive refractive power of the fifth lens group G5 becomes strong, it becomes difficult to suppress various aberrations such as astigmatism.

When the lower limit of conditional expression (9) is exceeded and the negative refractive power of the fifth lens group G5 becomes strong, the outermost angle ray is strongly diverged, making it difficult to ensure sufficient back focus and telecentricity.

By setting the lower limit of conditional expression (9) to −0.90, the effects of the present invention can be achieved more reliably. By setting the upper limit of conditional expression (9) to 0.90, the effects of the present invention can be achieved more reliably.

Further, the optical system of the present invention preferably satisfies the following conditional expressions.
(10) VD_G1P < 40.00
(11) ΔθgF_G1N>−0.010
(12) ΔθgF_G3P>−0.005
(13) ΔθgF_G4N < 0.010
(14) ΔθgF_G5N < 0.005
(15) nd_G1P > 1.8500
(16) nd_G5P > 1.8500
VD_G1P: Average value ΔθgF_G1N of the Abbe number at the d-line of the lenses having positive refractive power that constitute the first lens group G1: g-line and F of the lenses having negative refractive power that constitute the first lens group G1 Average value ΔθgF_G3P of the deviation ΔθgF of the partial dispersion ratio with respect to the line: Average value ΔθgF_G4N of the deviation ΔθgF of the partial dispersion ratio with respect to the g-line and the F-line of the lenses having positive refractive power constituting the third lens group G3: The fourth Average value ΔθgF_G5N of the deviation ΔθgF of the partial dispersion ratio for the g-line and F-line of the lenses having negative refractive power forming the lens group G4: the g-line of the lenses having negative refractive power forming the fifth lens group G5 and the deviation ΔθgF of the partial dispersion ratio with respect to the F-line nd_G1P: the average value of the refractive indices for the d-line of the lenses having positive refractive power constituting the first lens group G1 nd_G5P: constituting the fifth lens group G5 the average value of the refractive index at the d-line of a lens with positive refractive power

Conditional expression (10) defines a preferable range for the Abbe number at the d-line of the lens having positive refractive power that constitutes the first lens group G1.

When the average value of the Abbe numbers for the d-line of the lenses having positive refractive power constituting the first lens group G1 exceeds the upper limit of conditional expression (10), it becomes difficult to correct the chromatic aberration of magnification. .

Conditional expression (11) defines a preferable range of the deviation of the partial dispersion ratio for the g-line and the F-line of the lens having negative refractive power that constitutes the first lens group G1.

When the average value of the deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line of the lenses having negative refractive power constituting the first lens group G1 becomes smaller than the lower limit of conditional expression (11), the chromatic aberration of magnification is reduced. It becomes difficult to correct.

Conditional expression (12) defines a preferable range of the deviation of the partial dispersion ratio for the g-line and the F-line of the lens having positive refractive power that constitutes the third lens group G3.

When the average value of the deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line of the lenses having positive refractive power constituting the third lens group G3 becomes smaller than the lower limit of the conditional expression (12), longitudinal chromatic aberration occurs. becomes difficult to correct.

Conditional expression (13) defines a preferable range of the deviation of the partial dispersion ratio for the g-line and the F-line of the lens having negative refractive power that constitutes the fourth lens group G4.

When the average value of the deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line of the lenses having negative refractive power constituting the fourth lens group G4 exceeds the upper limit of conditional expression (13), longitudinal chromatic aberration occurs. becomes difficult to correct.

Conditional expression (14) defines a preferable range of the deviation of the partial dispersion ratio for the g-line and the F-line of the lens having negative refractive power that constitutes the fifth lens group G5.

When the average value of the deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line of the lenses having negative refractive power constituting the fifth lens group G5 exceeds the upper limit of conditional expression (14), longitudinal chromatic aberration occurs. and chromatic aberration of magnification become difficult to correct.

Conditional expression (15) defines a preferable range of the refractive index for the d-line of the lens having positive refractive power that constitutes the first lens group G1.

When the average value of the refractive index for the d-line of the lenses having positive refractive power constituting the first lens group G1 exceeds the lower limit of conditional expression (15), various aberrations such as curvature of field are corrected. becomes difficult.

Conditional expression (16) defines a preferable range of the refractive index for the d-line of the lens having positive refractive power that constitutes the fifth lens group G5.

When the lower limit of conditional expression (16) is exceeded and the average value of the refractive indices for the d-line of the lenses having positive refractive power constituting the fifth lens group G5 increases, various aberrations such as curvature of field are corrected. becomes difficult.

Further, in the optical system of the present invention, the first lens group G1 further comprises a meniscus lens with a negative refractive power with a convex surface facing the object side from the object side, a lens with a negative refractive power, and a lens with a positive refractive power. It is desirable to include an ordered arrangement of power lenses.

With such a configuration, it is possible to cope with a wide angle of view while suppressing distortion and astigmatism.

Further, in the optical system of the present invention, the fourth lens group G4 has a cemented surface with a convex surface facing the object side, and the refractive index of the medium on the object side is higher than the refractive index of the medium on the image plane side. It is desirable to have more than one set of lenses.

In the fourth lens group G4, by arranging one or more cemented lenses in which the cemented surface faces a convex surface toward the object side and the refractive index of the medium on the object side is higher than the refractive index of the medium on the image plane side, Various aberrations such as coma and spherical aberration can be suppressed.

Further, in the optical system of the present invention, it is desirable that the fifth lens group G5 has an aspherical surface such that the positive refractive power becomes weaker or the negative refractive power becomes stronger from the center of the optical axis toward the periphery. .

Since the fifth lens group G5 has an aspherical surface having the shape described above, field curvature and distortion can be suppressed.

Further, in the optical system of the present invention, it is desirable that the second lens group G2 is composed of two or less lenses.

With such a configuration, it is possible to reduce the weight of the parts that move during focusing.

Numerical examples and values corresponding to conditional expressions of the optical system of the present invention will be described below.

Next, the lens configuration of an example of the optical system of the present invention will be described. In the following description, the lens configuration will be described in order from the object side to the image plane side. Also, the notation of Ln in the examples indicates the n-th lens from the object side.

In [Surface data], the surface number is the number of the lens surface or aperture stop counted from the object side, r is the radius of curvature of each lens surface, d is the distance between each lens surface, and nd is for the d-line (wavelength 587.56 nm). The refractive index, vd is the Abbe number for the d-line, and θgF is the partial dispersion ratio between the g-line (wavelength 435.84 nm) and the F-line (wavelength 486.13 nm).

An asterisk (*) attached to the surface number indicates that the lens surface shape is aspheric.

The (diaphragm) attached to the surface number indicates that the aperture diaphragm is located at that position. ∞ (infinity) is entered for the radius of curvature for a plane or aperture stop.

[Aspheric surface data] shows the value of each coefficient that gives the aspheric shape of the lens surface marked with * in [Surface data]. The shape of the aspheric surface is represented by the following formula. In the following formula, y is the displacement from the optical axis in the direction orthogonal to the optical axis, z is the displacement (sag amount) in the optical axis direction from the intersection of the aspherical surface and the optical axis, r is the radius of curvature of the reference spherical surface, K represents the conic coefficient. A3, A4, A5, A6, A7, A8, A9, A3, A4, A5, A6, A7, A8, A9, They are represented by A10, A11, A12, A13, A14, A15 and A16.

[Various data] shows values such as the focal length in each shooting distance in-focus state.

[Variable distance data] shows the variable distance and BF values for each shooting distance in-focus state.

[Lens group data] indicates the surface number closest to the object side constituting each lens group and the combined focal length of the entire group.

In the aberration diagrams corresponding to each example, d, g, and C represent the d-line, g-line, and C-line, respectively, and ΔS and ΔM represent the sagittal image plane and meridional image plane, respectively. .

In addition, in the values of all the specifications below, unless otherwise specified, millimeters (mm) are used for the focal length f, radius of curvature r, distance between lens surfaces d, and other lengths. The system is not limited to this because the same optical performance can be obtained in both proportional enlargement and proportional reduction.

FIG. 1 is a lens configuration diagram of an optical system of Example 1 of the present invention.

Example 1 has, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens with negative refractive power. It is composed of a group G4 and a fifth lens group G5 of positive refractive power. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a biconvex lens L3, a biconcave lens L4, and an object side lens. The lens surfaces on both sides of the negative meniscus lens L1 and both sides of the positive meniscus lens L5 have a predetermined aspherical shape.

The second lens group G2 is composed only of a biconvex lens L6. The second lens group G2 moves toward the image plane during focusing from an infinite object distance to a short distance.

The third lens group G3 is composed of, in order from the object side, a negative meniscus lens L7 having a convex surface facing the image side, a biconvex lens L8, and a cemented lens composed of a biconvex lens L9 and a biconcave lens L10. Both lens surfaces of the convex lens L8 have a predetermined aspheric shape.

The fourth lens group G4 includes, in order from the object side, a cemented lens composed of a biconvex lens L11 and a biconcave lens L12, a negative meniscus lens L13 having a convex surface facing the object side, and a positive meniscus lens L14 having a convex surface facing the object side. It is composed of a cemented lens consisting of

The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L15, a negative meniscus lens L16 having a convex surface facing the object side, and a biconcave lens L17. has an aspherical shape.

The specification values of the optical system according to Example 1 are shown below.
Numerical example 1
Unit: mm
[Surface data]
Surface number rd nd vd θgF
Object plane ∞ (d0)
1* 161.4805 2.8015 1.58313 59.38 0.000922
2* 26.5270 2.7786
3 31.5334 1.5000 1.43700 95.10 0.056526
4 19.7048 9.4216
5 102.0441 3.2383 2.00069 25.46 0.011062
6 -444.8551 6.9281
7 -28.8940 1.0500 1.61340 44.27 -0.005289
8 74.0668 0.4500
9* 32.7524 3.0446 1.73077 40.50 -0.003978
10* 60.9305 (d10)
11 173.5602 5.9483 1.59349 67.00 0.008940
12 -34.1836 (d12)
13 -36.8596 0.9500 1.77047 29.74 0.000271
14 -173.8209 0.1500
15* 44.3951 6.8110 1.77250 49.50 -0.007316
16* -80.7953 0.1500
17 67.0933 3.8187 2.00100 29.13 0.003566
18 -237.0573 0.9500 1.61340 44.27 -0.005289
19 71.4524 3.3044
20 (Aperture) ∞ 1.4000
21 225.1592 7.2264 1.55032 75.50 0.027580
22 -22.5226 0.9000 1.85451 25.15 0.007183
23 93.2011 0.1500
24 40.7178 0.9000 1.77047 29.74 0.000271
25 23.0838 4.7828 1.43700 95.10 0.056526
26 99.7497 0.5000
27 47.5495 6.1520 2.00100 29.13 0.003566
28 -47.5495 0.1500
29 65.5334 0.9000 1.61340 44.27 -0.005289
30 35.4713 3.9899
31* -160.0000 1.5000 1.80610 40.73 -0.005657
32* 240.0000 (BF)
Image plane ∞

[Aspheric data]
1 side 2 side 9 side
K 0.00000 0.00000 0.00000
A4 9.70576E-06 2.95756E-06 -2.42866E-05
A6 -1.86433E-08 -1.66290E-08 5.00209E-08
A8 2.75229E-11 2.98210E-11 6.27171E-11
A10 -2.96311E-14 -1.49159E-13 -3.63242E-13
A12 2.10699E-17 2.74816E-16 3.31214E-16
A14 -6.75390E-21 -1.93740E-19 0.00000E+00
A16 0.00000E+00 0.00000E+00 0.00000E+00

10 faces 15 faces 16 faces
K 0.00000 0.00000 0.00000
A4 -2.30319E-05 -5.38648E-06 1.60401E-06
A6 5.54940E-08 7.55003E-09 7.34939E-10
A8 4.43002E-11 7.81632E-12 6.17228E-12
A10 -2.63258E-13 -1.85817E-14 2.52853E-14
A12 2.18796E-16 -1.74128E-17 -8.42590E-17
A14 0.00000E+00 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00 0.00000E+00

31 planes 32 planes
K 0.00000 0.00000
A4 -2.74145E-05 -1.43072E-06
A6 1.40603E-07 1.49542E-07
A8 -8.91781E-10 -7.26583E-10
A10 2.43875E-12 1.86133E-12
A12 -2.31913E-15 -2.03497E-15
A14 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00

[Various data]
INF
Focal length 23.86
F number 1.46
Full angle of view 2ω 84.43
Image height Y 21.63
Lens length 113.95

[Variable interval data]
INF 249mm
d0 ∞ 136.5000
d10 3.7171 9.2968
d12 8.1632 2.5835
BF 23.0355 23.0355

[Lens group data]
Group Starting surface Focal length
G1 1 -26.10
G2 11 48.64
G3 13 51.61
G4 21 -49.60
G5 27 36.37

FIG. 6 is a lens configuration diagram of the optical system of Example 2 of the present invention.

Example 2 comprises, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens with negative refractive power. It is composed of a group G4 and a fifth lens group G5 of positive refractive power. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a positive meniscus lens with a convex surface facing the object side. It is composed of a lens L3, a biconcave lens L4, and a positive meniscus lens L5 with a convex surface facing the object side. It has a predetermined aspheric shape.

The second lens group G2 is composed only of a biconvex lens L6. The second lens group G2 moves toward the image plane during focusing from an infinite object distance to a short distance.

The third lens group G3 is composed of, in order from the object side, a biconcave lens L7, a biconvex lens L8, and a cemented lens composed of a biconvex lens L9 and a negative meniscus lens L10 having a convex surface facing the image side. Both lens surfaces of the convex lens L8 have a predetermined aspheric shape.

The fourth lens group G4 is composed only of a cemented triplet consisting of a positive meniscus lens L11 having a convex surface facing the image side, a biconcave lens L12, and a positive meniscus lens L13 having a convex surface facing the object side.

The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L14, a negative meniscus lens L15 having a convex surface facing the object side, and a biconcave lens L16. has an aspherical shape.

The specification values of the optical system according to Example 2 are shown below.
Numerical example 2
Unit: mm
[Surface data]
Surface number rd nd vd θgF
Object plane ∞ (d0)
1* 98.0747 2.6500 1.51633 64.06 0.000431
2* 26.2988 2.7431
3 31.5978 1.5000 1.43700 95.10 0.056526
4 20.1096 7.4774
5 45.4016 3.6278 2.05090 26.94 0.005288
6 98.4178 7.8734
7 -30.9119 1.0500 1.65412 39.68 -0.003165
8 67.5752 0.5000
9* 35.5334 3.0364 1.80610 40.73 -0.005657
10* 71.3864 (d10)
11 138.6537 5.9557 1.59349 67.00 0.008940
12 -35.6502 (d12)
13 -34.4139 0.9500 1.77047 29.74 0.000271
14 556.2391 0.1500
15* 57.8783 5.7412 1.77250 49.50 -0.007316
16* -86.5801 0.2727
17 48.6890 5.8879 2.00100 29.13 0.003566
18 -97.5610 1.0000 1.85451 25.15 0.007183
19 -384.0925 1.6796
20 (Aperture) ∞ 2.2686
21 -359.1621 6.6225 1.55032 75.50 0.027580
22 -23.3708 1.0000 1.85451 25.15 0.007183
23 39.3014 3.2766 1.49700 81.61 0.037456
24 91.4740 0.8176
25 54.0211 5.8590 2.00100 29.13 0.003566
26 -46.1958 0.2364
27 47.6671 0.9345 1.73037 32.23 -0.000407
28 36.7621 4.0737
29* -150.0000 1.4000 1.80610 40.73 -0.005657
30* 270.0000 (BF)
Image plane ∞

[Aspheric Data]
1 side 2 side 9 side
K 0.00000 0.00000 0.00000
A4 3.84265E-06 -3.67055E-06 -2.51028E-05
A6 3.23398E-09 1.86413E-09 6.78972E-08
A8 -1.38777E-11 1.31003E-11 -1.63358E-11
A10 1.66457E-14 -1.41804E-13 -2.04320E-13
A12 -8.39283E-18 2.48960E-16 2.11272E-16
A14 1.49973E-21 -1.85862E-19 0.00000E+00
A16 0.00000E+00 0.00000E+00 0.00000E+00

10 faces 15 faces 16 faces
K 0.00000 0.00000 0.00000
A4 -2.39734E-05 -6.00813E-06 4.62100E-07
A6 7.24070E-08 8.77634E-09 -1.07297E-09
A8 -5.50282E-11 3.57499E-11 3.36217E-11
A10 -2.61072E-14 -1.19064E-13 -4.26202E-14
A12 1.66709E-17 9.19244E-17 -3.12046E-17
A14 0.00000E+00 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00 0.00000E+00

29 faces 30 faces
K 0.00000 0.00000
A4 -4.90052E-05 -2.69920E-05
A6 2.78055E-07 2.95567E-07
A8 -1.05923E-09 -1.06047E-09
A10 1.55034E-12 2.01880E-12
A12 -2.78235E-16 -1.69976E-15
A14 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00

[Various data]
INF
Focal length 27.50
F number 1.46
Full angle of view 2ω 76.53
Image height Y 21.63
Lens length 113.50

[Variable interval data]
INF 250mm
d0 ∞ 134.7000
d10 3.9697 7.9748
d12 6.3557 2.3506
BF 21.7787 21.7787

[Lens group data]
Group Starting surface Focal length
G1 1 -31.72
G2 11 48.40
G3 13 41.08
G4 21 -33.72
G5 25 34.45

FIG. 11 is a lens configuration diagram of an optical system according to Example 3 of the present invention.

Example 3 comprises, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, and a fourth lens with negative refractive power. It is composed of a group G4 and a fifth lens group G5 of positive refractive power. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a positive meniscus lens with a convex surface facing the object side. It is composed of a lens L3, a biconcave lens L4, and a biconvex lens L5, and the lens surfaces on both sides of the negative meniscus lens L1 have a predetermined aspherical shape.

The second lens group G2 is composed only of a biconcave lens L6. The second lens group G2 moves toward the object side during focusing from an infinite object distance to a short distance.

The third lens group G3 is composed of, in order from the object side, a biconvex lens L7 and a cemented lens composed of a biconvex lens L8 and a negative meniscus lens L9 having a convex surface facing the image side. The lens surface has a predetermined aspherical shape.

The fourth lens group G4 comprises, in order from the object side, a cemented lens composed of a positive meniscus lens L10 having a convex surface facing the image side and a negative meniscus lens L11 having a convex surface facing the image side, and a negative meniscus lens L11 having a convex surface facing the object side. It is composed of a cemented lens composed of a meniscus lens L12 and a positive meniscus lens L13 having a convex surface facing the object side.

The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L14, a negative meniscus lens L15 having a convex surface facing the object side, and a biconcave lens L16. has an aspherical shape.

The specification values of the optical system according to Example 3 are shown below.
Numerical example 3
Unit: mm
[Surface data]
Surface number rd nd vd θgF
Object plane ∞ (d0)
1* 158.9756 2.7000 1.69350 53.20 -0.005975
2* 25.3935 3.3481
3 35.3539 1.5000 1.43700 95.10 0.056526
4 21.6410 7.7549
5 55.0435 3.8563 2.00069 25.46 0.011062
6 237.1280 9.1250
7 -32.8486 1.1000 1.67300 38.26 -0.003721
8 82.0510 0.1500
9 47.1154 6.6041 1.80420 46.50 -0.007389
10 -48.9500 (d10)
11 -29.7477 0.9000 1.61340 44.27 -0.005289
12 193.4370 (d12)
13* 39.2782 8.3421 1.85135 40.10 -0.006643
14* -46.0226 0.1500
15 380.5234 6.0701 1.55032 75.50 0.027580
16 -29.8395 0.9000 1.77047 29.74 0.000271
17 -101.5703 1.0000
18 (Aperture) ∞ 2.8078
19 -90.2024 5.6214 1.59282 68.62 0.019331
20 -23.3653 0.8500 1.85451 25.15 0.007183
21 -3013.4949 0.1500
22 36.5386 0.8500 1.73037 32.23 -0.000407
23 22.0999 4.7992 1.43700 95.10 0.056526
24 64.2496 0.3000
25 42.6594 6.1923 2.00100 29.13 0.003566
26 -60.5255 0.1500
27 54.8315 0.8500 1.51742 52.15 0.004478
28 30.3227 4.3240
29* -160.0000 1.3800 1.80610 40.73 -0.005657
30* 240.0000 (BF)
Image plane ∞

[Aspheric data]
1 side 2 side 13 side
K 0.00000 0.00000 0.00000
A4 5.68260E-06 -1.42009E-06 -5.67998E-06
A6 -1.83236E-08 -2.84502E-08 4.49108E-09
A8 3.70160E-11 3.10653E-11 -7.86437E-12
A10 -4.32178E-14 -8.42275E-14 -1.89103E-14
A12 2.88252E-17 1.87072E-16 6.22723E-17
A14 -8.52313E-21 -2.07684E-19 0.00000E+00
A16 0.00000E+00 0.00000E+00 0.00000E+00

14 faces 29 faces 30 faces
K 0.00000 0.00000 0.00000
A4 2.73221E-06 -1.98555E-05 6.54967E-06
A6 3.75041E-09 8.21791E-08 9.04896E-08
A8 -2.06476E-11 -7.82409E-10 -6.10494E-10
A10 3.54685E-14 2.69898E-12 2.11233E-12
A12 -6.53308E-18 -3.10410E-15 -2.83245E-15
A14 0.00000E+00 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00 0.00000E+00

[Various data]
INF
Focal length 23.75
F number 1.46
Full angle of view 2ω 84.84
Image height Y 21.63
Lens length 114.15

[Variable interval data]
INF 248mm
d0 ∞ 134.0000
d10 7.5572 4.1234
d12 2.5000 5.9338
BF 22.3176 22.3176

[Lens group data]
Group Starting surface Focal length
G1 1 -313.82
G2 11 -41.97
G3 13 25.20
G4 19 -55.42
G5 25 38.53

FIG. 16 is a lens configuration diagram of an optical system according to Example 4 of the present invention.

Example 4 has, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens with positive refractive power. It is composed of a group G4 and a fifth lens group G5 of negative refractive power. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a negative meniscus lens L3 with a convex surface facing the object side. , and a cemented lens composed of a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side. The lens surfaces on both sides of L3 have a predetermined aspheric shape.

The second lens group G2 is composed only of a cemented lens composed of a negative meniscus lens L6 having a convex surface facing the object side and a positive meniscus lens L7 having a convex surface facing the object side. The second lens group G2 moves toward the image plane during focusing from an infinite object distance to a short distance.

The third lens group G3 includes, in order from the object side, a cemented lens composed of a biconvex lens L8 and a negative meniscus lens L9 having a convex surface facing the image side, a biconcave lens L10, and a positive meniscus lens L11 having a convex surface facing the object side. It is composed of a cemented lens consisting of

The fourth lens group G4 is composed of, in order from the object side, a biconvex lens L12 and a cemented lens composed of a negative meniscus lens L13 having a convex surface facing the object side and a biconvex lens L14.

The fifth lens group G5 includes, in order from the object side, a cemented lens composed of a biconcave lens L15 and a biconvex lens L16, a negative meniscus lens L17 having a convex surface facing the object side, and a negative meniscus lens L18 having a convex surface facing the image side. The lens surfaces on both sides of the negative meniscus lens L18 have a predetermined aspherical shape.

The specification values of the optical system according to Example 4 are shown below.
Numerical example 4
Unit: mm
[Surface data]
Surface number rd nd vd θgF
Object plane ∞ (d0)
1* 471.8640 3.2000 1.69350 53.18 -0.004302
2 23.3252 7.8659
3 37.2224 1.7000 1.59282 68.62 0.019331
4 20.3339 8.7321
5* 44.2713 1.8800 1.59201 67.02 0.008202
6* 19.3637 1.8808
7 25.5810 9.2425 1.85451 25.15 0.007183
8 2127.1283 1.4371 1.49700 81.61 0.037456
9 20.4660 (d9)
10 42.8355 0.7000 2.00069 25.46 0.011062
11 18.8523 4.5870 1.75211 25.05 0.015918
12 270.7821 (d12)
13 32.1984 6.5850 1.90043 37.37 -0.004428
14 -23.5539 0.8000 2.00100 29.13 0.003566
15 -51.9319 0.1500
16 -191.0397 0.8000 2.00100 29.13 0.003566
17 16.2949 5.0356 1.59349 67.00 0.008940
18 225.0938 2.7131
19 (Aperture) ∞ 2.6613
20 25.6241 5.0798 1.55032 75.50 0.027580
21 -63.4156 0.1500
22 38.7245 0.8000 1.90043 37.37 -0.004428
23 13.8480 7.5881 1.55032 75.50 0.027580
24 -64.2856 1.2046
25 -30.2250 0.8000 1.77047 29.74 0.000271
26 22.7584 7.5549 1.92286 20.88 0.028164
27 -37.8376 0.1500
28 36.8692 0.8000 1.85451 25.15 0.007183
29 26.5120 4.5946
30* -58.8156 1.3000 1.77250 49.50 -0.007316
31* -124.9641 (BF)
Image plane ∞

[Aspheric data]
1 side 30 sides 31 sides
K 0.00000 0.00000 0.00000
A4 1.29054E-05 -1.60215E-05 1.09092E-05
A6 -1.87125E-08 -6.24124E-08 -6.84574E-08
A8 2.25220E-11 7.16066E-10 1.60827E-09
A10 -1.73138E-14 -2.39500E-11 -3.07684E-11
A12 7.79393E-18 2.90938E-13 2.92894E-13
A14 -1.73492E-21 -1.40856E-15 -1.25091E-15
A16 1.20930E-25 2.43801E-18 1.96470E-18

5 sides 6 sides
K 0.00000 0.00000
A3 1.49399E-04 1.47841E-04
A4 -1.24864E-05 -1.66448E-05
A5 -1.65207E-05 -1.60637E-05
A6 2.20111E-06 2.03129E-06
A7 -7.50285E-08 -4.31628E-08
A8 -2.00492E-09 -5.27553E-09
A9 8.71437E-11 2.20676E-10
A10 5.16192E-12 7.70884E-12
A11 -5.66066E-14 -4.72437E-13
A12 -1.40295E-14 -1.93075E-14
A13 2.96473E-16 9.32046E-16
A14 4.93754E-18 1.12593E-16
A15 8.72088E-20 -7.91729E-18
A16 -7.73546E-21 1.31152E-19

[Various data]
INF
Focal length 14.48
F number 2.07
Full angle of view 2ω 114.27
Image height Y 21.63
Lens length 128.00

[Variable interval data]
INF 245mm
d0 ∞ 117.0000
d9 10.1953 14.0048
d12 7.8122 4.0028
BF 20.0000 20.0000

[Lens group data]
Group Starting surface Focal length
G1 1 -16.87
G2 10 131.52
G3 13 78.85
G4 20 28.77
G5 25 -110.77

FIG. 21 is a lens configuration diagram of a variable magnification optical system according to Example 5 of the present invention.

Example 5 has, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens with positive refractive power. It is composed of a group G4 and a fifth lens group G5 of negative refractive power. When zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 decreases, the distance between the second lens group G2 and the third lens group G3 increases, and the distance between the second lens group G2 and the third lens group G3 increases. The distance between the third lens group G3 and the fourth lens group G4 is reduced. The distance between the fourth lens group G4 and the fifth lens group G5 does not change during zooming. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a negative meniscus lens with a convex surface facing the object side in order from the body side. It is composed of a lens L3, a biconcave lens L4, and a positive meniscus lens L5 with a convex surface facing the object side. has a predetermined aspheric shape.

The second lens group G2 is composed only of a biconvex lens L6, and lens surfaces on both sides of the biconvex lens L6 have a predetermined aspherical shape. The second lens group G2 moves toward the image plane during focusing from an infinite object distance to a short distance.

The third lens group G3 is composed of, in order from the object side, a biconcave lens L7 and a cemented lens composed of a negative meniscus lens L8 having a convex surface facing the object side and a biconvex lens L9.

The fourth lens group G4 includes, in order from the object side, a cemented lens composed of a biconvex lens L10, a negative meniscus lens L11 having a convex surface facing the object side, and a positive meniscus lens L12 having a convex surface facing the object side; It is composed of a cemented lens composed of a negative meniscus lens L13 with a convex surface and a biconvex lens L14.

The fifth lens group G5 is composed of, in order from the object side, a cemented lens composed of a biconcave lens L15 and a positive meniscus lens L16 having a convex surface facing the object side, and a biconvex lens L17. The lens surface has a predetermined aspherical shape.

The specification values of the variable magnification optical system according to Example 5 are shown below.
Numerical example 5
Unit: mm
[Surface data]
Surface number rd nd vd θgF
Object plane ∞ (d0)
1* 70.4056 3.2000 1.69350 53.18 -0.004302
2 26.3386 9.8191
3 47.0173 1.8000 1.59282 68.62 0.019331
4 19.2586 8.4461
5* 50.7510 1.7500 1.59201 67.02 0.008202
6* 30.2021 8.4415
7 -58.3804 1.4000 1.59282 68.62 0.019331
8 60.3888 0.1500
9 40.5975 4.1753 1.86966 20.02 0.031106
10 150.6826 (d10)
11* 87.6942 2.3385 1.83441 37.28 -0.003944
12* -443.8662 (d12)
13 -228.6959 2.9412 1.90110 27.06 0.007486
14 128.5843 0.1500
15 23.9776 1.0000 2.00100 29.13 0.003566
16 18.0559 5.9169 1.51742 52.15 0.004478
17 -164.8550 (d17)
18 (Aperture) ∞ 1.1000
19 36.3694 3.8106 1.49700 81.61 0.037456
20 -228.9718 0.1500
21 23.8338 1.0000 1.77250 49.62 -0.008651
22 13.5457 6.9990 1.55032 75.50 0.027580
23 704.5748 2.7133
24 32.5040 0.8000 1.85451 25.15 0.007183
25 13.8138 4.5867 1.49700 81.61 0.037456
26 -177.6588 1.2521
27 -49.7382 1.0000 1.90043 37.37 -0.004428
28 15.9790 3.7832 1.94595 17.98 0.038540
29 45.9074 1.3235
30* 115.5755 2.3746 1.85135 40.10 -0.006643
31* -120.5601 (BF)
Image plane ∞

[Aspheric data]
1 side 5 sides 6 sides
K 0.00000 0.00000 0.00000
A4 6.76142E-06 -4.34833E-05 -3.67663E-05
A6 -5.65111E-09 5.14860E-07 5.77736E-07
A8 6.38647E-12 -2.29384E-09 -2.77453E-09
A10 -3.90433E-15 6.60944E-12 9.65781E-12
A12 1.33264E-18 -1.15011E-14 -2.15232E-14
A14 0.00000E+00 9.07791E-18 2.06192E-17
A16 0.00000E+00 0.00000E+00 0.00000E+00

11 sides 12 sides
K 0.00000 0.00000
A4 -2.76654E-06 2.58838E-06
A6 9.97585E-08 9.36424E-08
A8 -5.39819E-10 -5.25720E-10
A10 2.58396E-12 2.74232E-12
A12 0.00000E+00 0.00000E+00
A14 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00

30 faces 31 faces
K 0.00000 0.00000
A4 -8.79011E-06 1.19492E-05
A6 -6.32573E-08 -4.14136E-08
A8 -3.08927E-10 -4.07840E-10
A10 6.81396E-12 5.41523E-12
A12 0.00000E+00 0.00000E+00
A14 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00

[Various data]
Zoom ratio 1.60
Wide Angle Medium Telephoto Focal Length 14.50 17.90 23.15
F number 2.93 2.93 2.93
Full angle of view 2ω 114.20 100.78 84.98
Image height Y 21.63 21.63 21.63
Total lens length 133.00 130.36 130.13

[Variable interval data]
wide-angle medium-telephoto
d0 ∞ ∞ ∞
d10 15.8366 8.2249 1.7698
d12 4.3397 8.2201 10.0568
d17 10.4021 5.7620 2.0809
BF 20.0000 25.7267 33.8026

[Lens group data]
Group Starting surface Focal length
G1 1 -17.59
G2 11 87.93
G3 13 132.19
G4 19 29.86
G5 27-48.34

FIG. 28 is a lens configuration diagram of an optical system according to Example 6 of the present invention.

Example 6 has, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, and a fourth lens with positive refractive power. It is composed of a group G4 and a fifth lens group G5 of positive refractive power. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a positive meniscus lens L3 with a convex surface facing the image side. , a biconcave lens L4 and a biconvex lens L5, and the lens surfaces on both sides of the negative meniscus lens L1 have a predetermined aspherical shape.

The second lens group G2 is composed only of a negative meniscus lens L6 having a convex surface facing the image side. The second lens group G2 moves toward the object side during focusing from an infinite object distance to a short distance.

The third lens group G3 includes, in order from the object side, a positive meniscus lens L7 having a convex surface facing the object side, a biconvex lens L8, a negative meniscus lens L9 having a convex surface facing the object side, and a convex surface facing the image side. The lens surfaces on both sides of the biconvex lens L8 have a predetermined aspherical shape.

The fourth lens group G4 comprises, in order from the object side, a cemented lens composed of a positive meniscus lens L11 having a convex surface facing the image side and a negative meniscus lens L12 having a convex surface facing the image side, and a negative meniscus lens L12 having a convex surface facing the object side. It is composed of a cemented lens composed of a meniscus lens L13 and a biconvex lens L14.

The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L15, a negative meniscus lens L16 having a convex surface facing the object side, and a biconcave lens L17. has an aspherical shape.

The specification values of the optical system according to Example 6 are shown below.
Numerical example 6
Unit: mm
[Surface data]
Surface number rd nd vd θgF
Object plane ∞ (d0)
1* 161.7900 2.8000 1.69350 53.18 -0.004302
2* 32.1600 5.3700
3 55.0200 1.1000 1.77250 49.62 -0.008651
4 27.5400 14.0300
5 -64.1800 3.3100 2.00100 29.13 0.003566
6 -42.3300 1.7200
7 -39.6800 1.0000 1.71700 47.98 -0.006244
8 154.7400 0.1500
9 65.0800 6.2100 2.00100 29.13 0.003566
10 -146.5000 (d10)
11 -42.4900 1.0000 1.51680 64.20 0.001526
12 -244.6900 (d12)
13 38.7200 4.8000 1.95375 32.32 -0.000070
14 500.2700 0.1200
15* 56.1000 4.0000 1.69350 53.20 -0.005975
16* -200.0000 0.9600
17 753.2600 1.0000 1.86966 20.02 0.031106
18 44.1300 4.5500
19 -133.1200 2.8300 1.55032 75.50 0.027580
20 -52.8000 2.3100
21 (Aperture) ∞ 3.5600
22 -228.8400 8.3500 1.59282 68.62 0.019331
23 -18.3400 1.0000 1.85451 25.15 0.007183
24 -322.3600 0.1500
25 61.6500 1.0000 1.85451 25.15 0.007183
26 20.6300 8.1400 1.75500 52.32 -0.006799
27 -144.0200 1.4800
28 44.4500 6.2600 1.92286 20.88 0.028164
29 -62.0800 0.6000
30 69.2200 1.0000 1.54814 45.82 0.004146
31 28.7400 4.8500
32* -143.1800 1.6200 1.80610 40.73 -0.005657
33* 207.3800 (BF)
Image plane ∞

[Aspheric data]
1 side 2 sides 15 sides
K 0.00000 -1.00000 0.00000
A4 3.42610E-06 3.57650E-06 -6.40520E-06
A6 -1.83420E-09 2.20430E-09 6.10890E-09
A8 1.62440E-12 -2.63630E-12 -2.75570E-11
A10 -1.14130E-15 1.15770E-14 2.25740E-13
A12 2.61090E-19 -1.41510E-17 -6.85160E-16
A14 0.00000E+00 0.00000E+00 6.57300E-19
A16 0.00000E+00 0.00000E+00 0.00000E+00

16 faces 32 faces 33 faces
K 0.00000 0.00000 0.00000
A4 1.97340E-06 -1.86250E-05 5.56010E-06
A6 1.13490E-08 -2.85340E-09 2.29820E-08
A8 -5.37460E-11 -7.29380E-11 -2.99780E-11
A10 2.24120E-13 1.66680E-13 -1.45880E-14
A12 -4.61220E-16 0.00000E+00 0.00000E+00
A14 2.19690E-19 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00 0.00000E+00

[Various data]
INF
Focal length 20.33
F number 1.46
Full angle of view 2ω 96.47
Image height Y 21.63
Lens length 129.04

[Variable interval data]
INF 226mm
d0 ∞ 97.4379
d10 11.3900 3.7932
d12 2.0000 9.5968
BF 20.3784 20.3784

[Lens group data]
Group Starting surface Focal length
G1 1 -57.92
G2 11 -99.66
G3 13 37.61
G4 22 2394.83
G5 28 56.26

FIG. 33 is a lens configuration diagram of an optical system according to Example 7 of the present invention.

In Example 7, in order from the object side, the first lens group G1 has a negative refractive power, the second lens group G2 has a negative refractive power, the third lens group G3 has a positive refractive power, and the fourth lens has a positive refractive power. It is composed of a group G4 and a fifth lens group G5 of positive refractive power. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a positive meniscus lens L3 with a convex surface facing the image side. , a biconcave lens L4 and a biconvex lens L5, and the object-side lens surface of the negative meniscus lens L1 has a predetermined aspheric shape.

The second lens group G2 is composed only of a negative meniscus lens L6 having a convex surface facing the image side. The second lens group G2 moves toward the object side during focusing from an infinite object distance to a short distance.

The third lens group G3 includes, in order from the object side, a positive meniscus lens L7 having a convex surface facing the object side, a biconvex lens L8, a negative meniscus lens L9 having a convex surface facing the object side, and a convex surface facing the image side. The lens surfaces on both sides of the biconvex lens L8 have a predetermined aspherical shape.

The fourth lens group G4 comprises, in order from the object side, a cemented lens composed of a positive meniscus lens L11 having a convex surface facing the image side and a negative meniscus lens L12 having a convex surface facing the image side, and a negative meniscus lens L12 having a convex surface facing the object side. It is composed of a cemented lens composed of a meniscus lens L13 and a biconvex lens L14.

The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L15, a negative meniscus lens L16 having a convex surface facing the object side, and a biconcave lens L17. has an aspherical shape.

The specification values of the optical system according to Example 7 are shown below.
Numerical example 7
Unit: mm
[Surface data]
Surface number rd nd vd θgF
Object plane ∞ (d0)
1* 200.0000 2.8000 1.51633 64.06 0.000431
2 32.5800 5.3200
3 55.3700 1.0000 1.83481 42.72 -0.006698
4 24.6000 14.1700
5 -59.5900 3.2200 1.92286 20.88 0.028164
6 -39.5600 1.4500
7 -36.5700 1.0000 1.72342 37.99 0.002034
8 134.5600 0.1500
9 63.6800 6.5900 2.00100 29.13 0.003566
10 -105.2700 (d10)
11 -42.1700 1.0000 1.56883 56.04 0.001063
12 -245.8300 (d12)
13 36.2300 5.4100 1.90043 37.37 -0.004428
14 1000.0000 0.7000
15* 97.0800 4.0000 1.77250 49.46 -0.005328
16* -200.0000 0.6600
17 295.9200 1.0000 1.86966 20.02 0.031106
18 51.2600 4.1400
19 -182.8700 2.8400 1.59282 68.62 0.019331
20 -60.0400 2.4700
21 (Aperture) ∞ 3.6800
22 -176.3800 9.0700 1.61997 63.88 0.009171
23 -17.5800 1.0000 1.85451 25.15 0.007183
24 -275.0200 0.1500
25 59.2900 1.0000 1.85451 25.15 0.007183
26 20.3900 8.2900 1.75500 52.32 -0.006799
27 -143.1000 1.3300
28 43.2300 6.4800 1.86966 20.02 0.031106
29 -58.6500 0.6000
30 91.1500 1.0000 1.60342 38.01 0.002866
31 31.8400 4.5400
32* -144.9600 1.6200 1.80610 40.73 -0.005657
33* 205.6000 (BF)
Image plane ∞

[Aspheric data]
1 side 15 sides 16 sides
K 0.00000 0.00000 0.00000
A4 5.08610E-06 -9.10480E-06 -1.12080E-06
A6 -3.34790E-09 1.15870E-08 1.76880E-08
A8 3.40150E-12 -5.40470E-11 -8.80040E-11
A10 -2.06800E-15 6.08490E-13 7.42160E-13
A12 6.37810E-19 -1.94800E-15 -2.33440E-15
A14 0.00000E+00 1.87910E-18 2.22670E-18
A16 0.00000E+00 0.00000E+00 0.00000E+00

32 planes 33 planes
K 0.00000 0.00000
A4 -1.91220E-05 5.09400E-06
A6-5.64530E-09 2.07170E-08
A8 -6.18430E-11 -3.68810E-11
A10 1.57780E-13 0.00000E+00
A12 0.00000E+00 0.00000E+00
A14 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00

[Various data]
INF
Focal length 20.36
F number 1.46
Full angle of view 2ω 96.42
Image height Y 21.63
Lens length 129.06

[Variable interval data]
INF 227mm
d0 ∞ 97.7171
d10 10.0200 3.3892
d12 2.0000 8.6308
BF 20.3590 20.3590

[Lens group data]
Group Starting surface Focal length
G1 1 -58.98
G2 11 -89.64
G3 13 36.15
G4 22 690.99
G5 28 63.15

FIG. 38 is a lens configuration diagram of an optical system according to Example 8 of the present invention.

Example 8 has, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, and a fourth lens with positive refractive power. It is composed of a group G4 and a fifth lens group G5 of positive refractive power. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, and a positive meniscus lens L3 with a convex surface facing the object side. , a biconcave lens L4 and a biconvex lens L5, and the lens surfaces on both sides of the negative meniscus lens L1 have a predetermined aspherical shape.

The second lens group G2 is composed only of a biconcave lens L6. The second lens group G2 moves toward the object side during focusing from an infinite object distance to a short distance.

The third lens group G3 is composed of, in order from the object side, a biconvex lens L7, a biconvex lens L8, a biconcave lens L9, and a positive meniscus lens L10 having a convex surface facing the object side. has a predetermined aspheric shape.

The fourth lens group G4 comprises, in order from the object side, a cemented lens composed of a positive meniscus lens L11 having a convex surface facing the image side and a negative meniscus lens L12 having a convex surface facing the image side, and a negative meniscus lens L12 having a convex surface facing the object side. It is composed of a cemented lens composed of a meniscus lens L13 and a biconvex lens L14.

The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L15, a negative meniscus lens L16 having a convex surface facing the object side, and a biconcave lens L17. has an aspherical shape.

The specification values of the optical system according to Example 8 are shown below.
Numerical example 8
Unit: mm
[Surface data]
Surface number rd nd vd θgF
Object plane ∞ (d0)
1* 89.3100 2.8000 1.77250 49.50 -0.007316
2* 25.5200 5.0000
3 45.8200 1.0000 1.91082 35.25 -0.002688
4 26.1800 8.8900
5 84.3500 3.5300 1.90366 31.31 0.002786
6 265.7400 6.7600
7 -50.1600 1.0000 1.55032 75.50 0.027580
8 115.0800 0.1500
9 62.6300 6.5700 2.00100 29.13 0.003566
10 -134.5400 (d10)
11 -41.6600 1.0000 1.48749 70.44 0.009085
12 1116.3700 (d12)
13 50.2600 5.0500 1.87070 40.73 -0.006808
14 -114.6900 0.1200
15* 145.0900 4.0000 1.85135 40.10 -0.006643
16* -200.0000 1.7200
17 -172.8600 1.0000 1.86966 20.02 0.031106
18 82.6400 1.4400
19 77.9100 2.7600 1.55032 75.50 0.027580
20 833.4400 4.3100
21 (Aperture) ∞ 3.7400
22 -145.7400 8.1300 1.49700 81.61 0.037456
23 -17.7700 1.0000 1.85451 25.15 0.007183
24 -48.1300 0.1500
25 588.0900 1.0000 1.85451 25.15 0.007183
26 20.8800 8.7100 1.80420 46.50 -0.007389
27 -85.0100 1.6600
28 47.2200 6.6500 1.92286 20.88 0.028164
29 -59.2100 0.6000
30 65.8300 1.0000 1.78472 25.72 0.013736
31 32.7300 4.9900
32* -156.4300 1.6200 1.85135 40.10 -0.006643
33* 203.5200 (BF)
Image plane ∞

[Aspheric data]
1 side 2 sides 15 sides
K 0.00000 -1.00000 0.00000
A4 1.09530E-06 1.96920E-06 -5.89030E-07
A6 -1.31490E-09 -1.42520E-09 -1.84690E-09
A8 7.23620E-13 -2.78970E-12 6.65580E-11
A10 -2.14310E-16 -2.66360E-15 -3.41850E-13
A12 2.53790E-20 3.68990E-18 6.95290E-16
A14 0.00000E+00 0.00000E+00 -5.05920E-19
A16 0.00000E+00 0.00000E+00 0.00000E+00

16 faces 32 faces 33 faces
K 0.00000 0.00000 0.00000
A4 3.78710E-06 -2.34740E-05 -3.94420E-06
A6 -5.67530E-09 -5.47810E-08 -2.70810E-08
A8 9.47370E-11 3.60940E-10 3.19840E-10
A10 -5.16290E-13 -9.95610E-13 -8.54480E-13
A12 1.09790E-15 1.04770E-15 7.35040E-16
A14 -8.30860E-19 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00 0.00000E+00

[Various data]
INF
Focal length 20.29
F number 1.46
Full angle of view 2ω 94.46
Image height Y 21.63
Lens length 129.05

[Variable interval data]
INF 225mm
d0 ∞ 96.2352
d10 10.6800 3.5577
d12 2.0000 9.1223
BF 20.0244 20.0245

[Lens group data]
Group Starting surface Focal length
G1 1 -75.93
G2 11 -82.36
G3 13 38.11
G4 22 285.35
G5 28 61.12

Values corresponding to conditional expressions corresponding to the above examples are shown below.
[Value corresponding to conditional expression]
Conditional expression Example 1 Example 2 Example 3
(1) ΔθgF_G4P > 0.000 0.042 0.033 0.038
(2) VD_GF4P > 50.00 85.30 78.55 81.86
(3) ΔθgF_G5L1 > 0.000 0.004 0.004 0.004
(4) VD_GF5L1 < 40.00 29.13 29.13 29.13
(5) -1.50 < f/f1 < 0.00 -0.91 -0.87 -0.08
(6) 0.05 < f/|f2| < 0.75 0.49 0.57 0.57
(7) 0.10 < f/f3 < 1.20 0.46 0.67 0.94
(8) -1.00 < f/f4 < 1.00 -0.48 -0.82 -0.43
(9) -1.00 < f/f5 < 1.00 0.66 0.80 0.62
(10) VD_G1P < 40.00 32.98 33.84 35.98
(11) ΔθgF_G1N > -0.010 0.017 0.018 0.016
(12) ΔθgF_G3P > -0.005 -0.002 -0.002 0.010
(13) ΔθgF_G4N < 0.010 0.004 0.007 0.003
(14) ΔθgF_G5N < 0.005 -0.005 -0.003 -0.001
(15) nd_G1P > 1.8500 1.8657 1.9285 1.9024
(16) nd_G5P > 1.8500 2.0010 2.0010 2.0010

Conditional expression Example 4 Example 5T
(1) ΔθgF_G4P > 0.000 0.028 0.034
(2) VD_GF4P > 50.00 75.50 79.57
(3) ΔθgF_G5L1 > 0.000 0.028 0.016
(4) VD_GF5L1 < 40.00 20.88 29.04
(5) -1.50 < f/f1 < 0.00 -0.86 -1.32
(6) 0.05 < f/|f2| < 0.75 0.11 0.26
(7) 0.10 < f/f3 < 1.20 0.18 0.18
(8) -1.00 < f/f4 < 1.00 0.50 0.78
(9) -1.00 < f/f5 < 1.00 -0.13 -0.48
(10) VD_G1P < 40.00 25.15 20.02
(11) ΔθgF_G1N > -0.010 0.015 0.011
(12) ΔθgF_G3P > -0.005 0.002 0.004
(13) ΔθgF_G4N < 0.010 -0.004 -0.001
(14) ΔθgF_G5N < 0.005 0.000 -0.004
(15) nd_G1P > 1.8500 1.8545 1.8697
(16) nd_G5P > 1.8500 1.9229 1.8986

Conditional expression Example 6 Example 7 Example 8
(1) ΔθgF_G4P > 0.000 0.006 0.001 0.015
(2) VD_GF4P > 50.00 60.47 58.10 64.05
(3) ΔθgF_G5L1 > 0.000 0.028 0.016 0.028
(4) VD_GF5L1 < 40.00 20.88 25.01 20.88
(5) -1.50 < f/f1 < 0.00 -0.35 -0.35 -0.27
(6) 0.05 < f/|f2| < 0.75 0.20 0.23 0.25
(7) 0.10 < f/f3 < 1.20 0.54 0.56 0.53
(8) -1.00 < f/f4 < 1.00 0.01 0.03 0.07
(9) -1.00 < f/f5 < 1.00 0.36 0.32 0.33
(10) VD_G1P < 40.00 29.13 25.01 30.22
(11) ΔθgF_G1N > -0.010 -0.006 -0.001 0.006
(12) ΔθgF_G3P > -0.005 0.007 0.003 0.005
(13) ΔθgF_G4N < 0.010 0.007 0.007 0.007
(14) ΔθgF_G5N < 0.005 -0.001 -0.001 0.004
(15) nd_G1P > 1.8500 2.0010 1.9619 1.9523
(16) nd_G5P > 1.8500 1.9229 1.8697 1.9229
*Example 5 shows the value of Tele.

G1: 1st lens group G2: 2nd lens group G3: 3rd lens group G4: 4th lens group G5: 5th lens group S: Aperture stop I: Image plane CC line (wavelength λ = 656.3 nm)
d d line (wavelength λ=587.6 nm)
gg line (wavelength λ = 435.8 nm)
Y image height ΔS sagittal image plane ΔM medional image plane

Claims (8)

In order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive or negative refractive power, a third lens group G3 having positive refractive power, and a positive or negative It consists of a fourth lens group G4 having refractive power and a fifth lens group G5 having positive or negative refractive power. The distance between the first lens group G1 and the second lens group G2 is changed, the distance between the second lens group G2 and the third lens group G3 is changed at the same time, and the fourth lens group G4 is positive refractive. The fifth lens group G5 includes a lens having a positive refractive power and a lens having a negative refractive power, and the fifth lens group G5 includes a lens having a positive refractive power and a lens having a negative refractive power. An optical system characterized by arranging a lens having a positive refractive power or a cemented lens including a lens having a positive refractive power on one side thereof, and satisfying the following conditional expressions (1) to (4).
(1) ΔθgF_G4P > 0.000
(2) VD_GF4P > 50.00
(3) ΔθgF_G5P > 0.000
(4) VD_GF5P < 40.00
however,
ΔθgF_G4P: Average value of the deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line of the lenses having positive refractive power constituting the fourth lens group G4 The deviation ΔθgF of the partial dispersion ratio for the g-line and the F-line ΔθgF=θgF−(0.648285−0.00180123×VD) where θgF is the partial dispersion ratio for the g-line and F-line, and VD is the Abbe number at the d-line.
VD_GF4P calculated as: average value of Abbe numbers at the d-line of the lenses having positive refractive power that constitute the fourth lens group G4 ΔθgF_G5P: of the lenses having positive refractive power that constitute the fifth lens group G5 Average value VD_GF5P of partial dispersion ratio deviation ΔθgF for g-line and F-line: average value of Abbe numbers for d-line of lenses having positive refractive power that constitute the fifth lens group G5
2. The optical system according to claim 1, wherein the groups other than the second lens group G2 are fixed with respect to the image plane during focusing.
3. The optical system according to claim 1, wherein the following conditional expression is satisfied.
(5) -1.50 < f/f1 < 0.00
(6) 0.05<f/|f2|<0.75
(7) 0.10 < f/f3 < 1.20
(8) -1.00 < f/f4 < 1.00
(9) -1.00 < f/f5 < 1.00
however,
f: focal length of the entire lens system when photographing at infinity f1: focal length of the first lens group G1 when photographing at infinity f2: photographing at infinity focal length f3 of the second lens group G2 at time: focal length f4 of the third lens group G3 at infinity photography: focal length f5 of the fourth lens group G4 at infinity photography: focal length f5 of the fourth lens group G4 at infinity photography Focal length of the fifth lens group G5
4. The optical system according to claim 1, wherein the following conditional expression is satisfied.
(10) VD_G1P < 40.00
(11) ΔθgF_G1N>−0.010
(12) ΔθgF_G3P>−0.005
(13) ΔθgF_G4N < 0.010
(14) ΔθgF_G5N < 0.005
(15) nd_G1P > 1.8500
(16) nd_G5P > 1.8500
however,
VD_G1P: Average value ΔθgF_G1N of the Abbe number at the d-line of the lenses having positive refractive power that constitute the first lens group G1: g-line and F of the lenses having negative refractive power that constitute the first lens group G1 Average value ΔθgF_G3P of the deviation ΔθgF of the partial dispersion ratio with respect to the line: Average value ΔθgF_G4N of the deviation ΔθgF of the partial dispersion ratio with respect to the g-line and the F-line of the lenses having positive refractive power constituting the third lens group G3: The fourth Average value ΔθgF_G5N of the deviation ΔθgF of the partial dispersion ratio for the g-line and F-line of the lenses having negative refractive power forming the lens group G4: the g-line of the lenses having negative refractive power forming the fifth lens group G5 and the deviation ΔθgF of the partial dispersion ratio with respect to the F-line nd_G1P: the average value of the refractive indices for the d-line of the lenses having positive refractive power constituting the first lens group G1 nd_G5P: constituting the fifth lens group G5 the average value of the refractive index at the d-line of a lens with positive refractive power
The first lens group G1 includes a structure in which a meniscus lens with a negative refractive power with a convex surface facing from the object side to the object side, a lens with a negative refractive power, and a lens with a positive refractive power are arranged in this order. 5. The optical system according to any one of claims 1 to 4, characterized in that:
The fourth lens group G4 is characterized by having one or more cemented lenses whose cemented surfaces are convex toward the object side and the refractive index of the medium on the object side is higher than the refractive index of the medium on the image plane side. 6. The optical system according to any one of claims 1 to 5.
7. The fifth lens group G5 has an aspherical surface such that the positive refractive power becomes weaker or the negative refractive power becomes stronger toward the periphery from the center of the optical axis. The optical system according to any one of the above.
8. The optical system according to any one of claims 1 to 7, wherein the second lens group G2 is composed of two lenses or less.

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