JP2014115319A - Optical system and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system which is hardly scratched and can maintain optical performance, and an optical device.SOLUTION: A third lens group L3 arranged at the outermost side among a plurality of lens groups is a cemented lens obtained by coupling a plurality of lenses made of different resin materials. When the pencil hardness of the material of a lens L3a having the largest center thickness among lenses constituting the cemented lens is represented by H1, the pencil hardness of the material of a lens L3b arranged at the outermost side among the cemented lens is represented by H2, the center thickness of the lens L3a having the largest center thickness is represented by t1, the coefficient of water absorption of the material of the lens L3a having the largest center thickness is represented by A, the center thickness of the outermost lens L3b is represented by t2, and the coefficient of water absorption of the material of the outermost lens L3b is represented by B, the following conditional expressions are satisfied: H1<H2, 1<B/A<35, and 1.6≤t1/t2<20.

Description

  The present invention relates to an optical system and an optical apparatus.

  A single lens made of a resin material is cheaper and lighter than a single lens made of optical glass, but has low hardness and is easily damaged. Therefore, when using a lens made of a resin material for the eyepiece of a single-lens reflex camera, it is necessary to select a material having sufficient hardness that does not easily damage the outermost lens.

  Patent Document 1 discloses a finder optical system in which the most observing lens material is made of resin. In Patent Document 2, an eyepiece lens is composed of four lenses.

JP 2001-311881 A JP 2000-111810 A

  However, the acrylic resin has a high hardness but also a high water absorption rate, and the lens surface shape and refractive index change with time, and this change occurs over a long period of time, particularly in a lens having a thick center thickness, and the optical performance deteriorates. Further, when the center thickness of the eyepiece lens is reduced, the observation magnification is reduced. Further, the polycarbonate resin has a low water absorption rate, and changes in the lens surface shape and refractive index are small. However, since the hardness is low, the polycarbonate resin is easily damaged. Since the eyepiece of Patent Document 2 has a large number of lenses, it tends to cause an increase in the size of an optical system, a complicated mechanical configuration, and a decrease in transmittance.

  An object of the present invention is to provide an optical system and an optical apparatus that are less likely to be scratched and can maintain optical performance.

  The optical system of the present invention is an optical system in which a cemented lens in which a plurality of lenses made of different resin materials are cemented is disposed on the outermost side, and is the material of the thickest lens material that constitutes the cemented lens. The pencil hardness is H1, the pencil hardness of the outermost lens material of the cemented lens is H2, the center thickness of the thickest lens and the water absorption rate of the material are t1, A, and the center thickness of the outermost lens. When the water absorption rate of the material is t2 and B, the following conditional expression is satisfied.

H1 <H2
1 <B / A <35
1.6 ≦ t1 / t2 <20

  ADVANTAGE OF THE INVENTION According to this invention, the optical system and optical apparatus which are hard to be damaged and can maintain optical performance can be provided.

Cross-sectional view of main parts when a finder optical system having an eyepiece having a resin material cemented lens of the present invention is applied to a single-lens reflex camera It is sectional drawing of the eyepiece of this invention. (Examples 1 and 3) It is an aberration diagram of the eyepiece lens of the present invention. Example 1 It is sectional drawing of the eyepiece of this invention. (Examples 2, 4 to 7) It is an aberration diagram of the eyepiece lens of the present invention. (Example 2) It is an aberration diagram of the eyepiece lens of the present invention. (Example 3) It is an aberration diagram of the eyepiece lens of the present invention. Example 4 It is an aberration diagram of the eyepiece lens of the present invention. (Example 5) It is an aberration diagram of the eyepiece lens of the present invention. (Example 6) It is an aberration diagram of the eyepiece lens of the present invention. (Example 7) It is sectional drawing of the eyepiece of this invention. (Example 8) It is an aberration diagram of the eyepiece lens of the present invention. (Example 8)

  FIG. 1 is a cross-sectional view of a main part of a digital single-lens reflex camera (optical apparatus, imaging device) of the present embodiment. A digital single lens reflex camera includes a photographing lens (photographing optical system) 1, a quick return mirror (QR mirror) 2, a focusing screen (Fresnel lens) 3, a penta roof mirror (upright image forming member) 4, an eyepiece (eyepiece optical system). ) 5. The focusing screen 3, the penta roof mirror 4, and the eyepiece lens 5 constitute a finder optical system for observing an object image formed on a predetermined surface.

  The photographing lens 1 forms an optical image of an object (subject), and a lens barrel (lens device, optical device) that houses the photographing lens 1 is configured to be detachable from a camera body (not shown). Since the present invention can also be applied to a lens-integrated digital camera, the lens device may be fixed to the camera body.

  The quick return mirror 2 is configured to be movable between a mirror-down position shown in FIG. 1 and a mirror-up position (not shown), and reflects the light beam from the photographing lens 1 to the upper finder optical system at the mirror-down position. Yes. In the mirror down position, the light beam from the photographic lens 1 is retracted from the optical path and reaches the imaging surface (image surface IP of the photographic lens 1). On the image plane IP, an imaging surface of a photoelectric conversion element (imaging means) such as a CCD sensor or a CMOS sensor or a photosensitive surface such as a film (imaging means) is disposed. The photoelectric conversion element photoelectrically converts an image corresponding to the subject image formed on the mat surface (part of the subject image, an image of a portion larger than the subject image).

  A subject image (finder image) is formed on the matte surface of the focusing screen 3 by the photographing lens 1.

  The penta roof mirror 4 converts a subject image (an inverted inverted image) on the mat surface into an erect image, and includes an incident portion 4a, a first reflecting mirror 4b, a second reflecting mirror 4c, and an emitting portion 4d. The light beam of the subject image from the mat surface is incident on the incident portion 4a. The roof-shaped first reflecting mirror 4b reflects the luminous flux of the subject image formed on the mat surface incident from the incident portion 4a to the subject image side (object side). The second reflecting mirror 4c reflects the light beam reflected by the first reflecting mirror 4b to the observation side, and the light beam is emitted from the emitting unit 4d. The erect image forming member may be composed of a penta roof prism or a plurality of prisms in addition to the penta roof mirror.

  The eyepiece 5 is an optical system that enables the user to enlarge and observe the object image collected at the focal position. The eyepiece 5 is disposed in order from the object side to the observation side along the optical path of the viewfinder optical system, the first lens unit L1 having a negative refractive power, the second lens unit L2 having a positive refractive power, and the most side of the observation side. The third lens unit L3 has a three-group configuration having a negative refractive power. The second lens unit L2 includes one positive lens. The third lens unit L3 is a cemented lens in which a plurality of lenses made of different resin materials are cemented. Low price and light weight are realized by using resin material. Diopter adjustment is performed by moving the second lens unit L2 along the optical axis of the eyepiece 5. Each lens group is composed of a single lens or a plurality of lenses. In the eyepiece, the outermost lens surface may be exposed to the outside (an antireflection film or the like may be formed).

  Reference numeral 6 denotes an eye point where an observer's eye is located. The distance from the last lens surface of the eyepiece 5 to the eye point 6 on the observation side corresponds to the eye relief.

  In the eyepiece lens 5, the most observation side (eye point side 6) is a cemented lens in which a plurality of lenses made of a resin material are cemented.

  If the pencil hardness of the thickest lens constituting the cemented lens is H1, and the pencil hardness of the most observing lens (outermost lens) of the cemented lens is H2, the following conditional expression is satisfied.

H1 <H2 (1)
The pencil hardness represents the hardness (the hardness of the pencil that scratches the surface and does not scratch the surface) whether or not the surface is damaged by the pencil, and the measurement is based on the JIS measurement method. Conditional expression (1) defines the hardness of each lens material of the cemented lens in order to improve the weather resistance of the eyepiece lens.

  Further, the center thickness of the thickest lens constituting the cemented lens and the water absorption rate of the material are t1 and A, respectively, and the center thickness of the lens closest to the observation side of the cemented lens and the water absorption rate of the material are t2 and B, respectively. Then, it is preferable that the following conditional expression is satisfied.

1 <B / A <35 (2)
1.6 ≦ t1 / t2 <20 (3)
The water absorption is a numerical value that represents the amount of water absorption when a certain material is immersed in water and sufficiently absorbs water as a ratio to a certain amount of dry matter, and the measurement is based on the JIS measurement method. Conditional expression (2) defines the water absorption rate of the material of each lens of the cemented lens in consideration of the optical performance of the eyepiece lens. Below the lower limit, the deterioration of optical performance due to water absorption becomes significant. The upper limit is not particularly limited, but is added for convenience in selecting a general resin material. Conditional expression (3) prescribes the ratio of the thickness on the optical axis of each lens of the cemented lens. When the lower limit is not reached, deterioration of optical performance due to water absorption becomes remarkable. The upper limit is not particularly limited, but is added for convenience in selecting a general resin material. As described above, the conditional expressions (1), (2), and (3) are for improving the weather resistance and reducing the deterioration of the optical performance of the finder optical system due to changes over time, while realizing a high finder magnification. It is a conditional expression. By increasing the center thickness of the lens having a low water absorption rate of the cemented lens, a high magnification can be achieved while reducing deterioration of the optical performance of the finder optical system due to changes over time.

  More preferably, H2 is set to a pencil hardness of 3H or higher.

  More preferably, the numerical ranges of conditional expressions (2) and (3) should be set as follows.

1.2 <B / A <32.0 (2a)
1.6 ≦ t1 / t2 <15 (3a)
According to each embodiment, it is possible to obtain a finder optical system having a high-magnification eyepiece while maintaining strength with a simple configuration and little change with time.

  Furthermore, it is preferable that the following conditional expression is satisfied, where N1 is the refractive index of the thickest lens material constituting the cemented lens, and N2 is the refractive index of the most observing lens. Below the lower limit, the optical performance deteriorates because the refractive index of the thick lens is lowered. The upper limit is not particularly limited, but is added for convenience in selecting a general resin material.

1 <N1 / N2 <1.3 (4)
In order to increase the observation magnification of the finder optical system, it is necessary to shorten the distance from the focusing screen 3 to the eyepiece lens 5 (the optical path length to the principal point position of the eyepiece lens 5). It is desirable that the negative lens has a large refractive power. When the conditional expression (4) is satisfied, the refractive index of the lens with the thickest central thickness of the cemented lens is increased, so that the refractive power of the negative lens can be increased.

  When the Abbe number of the second lens unit L2 is νd2, and the Abbe number of the thickest lens material of the third lens unit L3 is νd3, the following conditional expression is preferably satisfied.

vd3 <vd2 (5)
Magnification chromatic aberration and axial chromatic aberration can be improved by increasing the Abbe number of the second lens unit L2 and decreasing the Abbe number of the third lens unit L3.

  Further, when the center thickness of the third lens unit L3 is d3, the focal length of the entire system when the finder optical system is −1 diopter is f, and the focal length of the first lens unit L1 is f1, the following conditional expression is satisfied. It is preferable.

0.13 <d3 / f <0.21 (6)
−1 <f1 / f <−0.7 (7)
Conditional expressions (6) and (7) are conditional expressions for increasing the observation magnification while sufficiently securing the eye point 6. By increasing the thickness of the third lens unit L3 of the negative lens, the distance from the focusing screen 3 to the eyepiece lens 5 (the optical path length to the main point position of the eyepiece lens) can be shortened, and the observation magnification of the finder system can be increased. can do.

  When the value is smaller than the lower limit of conditional expression (6), the G3 lens cannot be made sufficiently thick, and the magnification of the finder system cannot be made sufficiently large. If the upper limit of conditional expression (6) is too large, a sufficient distance from the observation side surface of the G3 lens to the eye point cannot be secured.

  If it becomes smaller than the lower limit of conditional expression (7), the power of the negative lens G1 becomes too weak, and it is impossible to bounce up the light beam, and a sufficient eye point cannot be secured. If the upper limit of conditional expression (7) is exceeded, the power of G1, which is a negative lens, becomes too strong, and the magnification of the finder system cannot be sufficiently increased.

  When the radius of curvature of the cemented lens surface of the cemented lens is Ra and the radius of curvature of the lens surface closest to the observation side is Rb, the following conditional expression is preferably satisfied.

0.9 <Ra / Rb <1.1 (8)
That is, the shape of the cemented lens surface of the cemented lens and the shape of the lens surface closest to the observation side (eye point side) of the cemented lens are made substantially the same. If the two are greatly different, there is a problem in that the mold structure becomes complicated at the time of manufacturing by injection molding or the like. When the conditional expression (8) is satisfied, the third lens unit L3 can be easily manufactured.

  Examples of the present invention will be described below. In the spherical aberration diagram, the solid line d is the d line, and the two-dot chain line g is the g line. In the astigmatism diagram, M is a meridional image plane, and S is a sagittal image plane. Distortion is shown for the d-line. In the lateral chromatic aberration diagram, the g-line with respect to the d-line is shown. h is the image height on the mat surface side.

  The eyepiece 5 of Example 1 (Numerical Example 1) has a cross-sectional configuration shown in FIG. FIGS. 3A, 3B, and 3C are aberration diagrams when the viewfinder diopter of the eyepiece 5 is −1 diopter (standard diopter), −3 diopter, and +1 diopter. The third lens unit L3 is composed of a styrene resin, and is a cemented lens in which the lens L3a having the thickest central thickness and the lens L3b on the most observation side are composed of an acrylic resin and are joined together. It is configured.

  The pencil hardness of the lens L3a made of styrene resin is 2H, and the pencil hardness of the lens L3b made of acrylic resin is 3H. Since the lens on the most observation side (the outermost lens) is made of a resin material having a high pencil hardness, it is possible to provide an eyepiece (finder optical system) that is hard to be damaged and has excellent weather resistance. In addition, by increasing the center thickness of the low water absorption lens L3a compared to the high water absorption lens L3b, the optical performance of the finder optical system can be reduced while deterioration of the optical performance of the finder optical system due to changes over time is realized. doing.

  The eyepiece 5 of Example 2 (Numerical Example 2) has a cross-sectional configuration shown in FIG. FIGS. 5A, 5B, and 5C are aberration diagrams when the finder diopter in the eyepiece 5 is −1 diopter (standard diopter), −3 diopter, and +1 diopter. The third lens unit L3 is composed of an acrylic resin, is composed of the lens L3a closest to the object side, a styrene resin, the lens L3b having the thickest central wall, the acrylic resin, and the lens L3c closest to the observation side. This is a cemented lens composed of three lenses.

  The pencil hardness of the lens L3b is 2H, and the pencil hardness of the lenses L3a and L3c is 3H. By configuring the lens L3c with a resin material having a pencil hardness larger than that of the lens L3b, an eyepiece (finder optical system) that is hard to be damaged and has excellent weather resistance can be provided. In addition, since the lens L3a is also formed from a resin material having a high pencil hardness, the lens L3a is not easily damaged during assembly and is easy to handle. In addition, the lens L3b with a low water absorption rate is made thicker than the lens L3c with a high water absorption rate, thereby reducing the deterioration of the optical performance of the finder optical system due to changes over time and increasing the magnification of the finder optical system. doing.

  The eyepiece 5 of Example 3 (Numerical Example 3) also has the configuration of the cross-sectional view shown in FIG. 6A, 6B, and 6C are aberration diagrams when the viewfinder diopter of the eyepiece 5 is -1 diopter (standard diopter), -3 diopter, and +1 diopter. The third lens unit L3 is composed of a polycarbonate-based resin, and is a cemented lens in which the lens L3a having the thickest central thickness and the lens L3b on the most observation side are composed of an acrylic resin and are joined together. It is configured.

  The pencil hardness of the lens L3a made of polycarbonate resin is B, and the pencil hardness of the lens L3b made of acrylic resin is 3H. By constructing the lens closest to the observation side with a resin material having a high pencil hardness, it is possible to provide an eyepiece lens (finder optical system) that is hard to be damaged and has excellent weather resistance. In addition, by increasing the center thickness of the low water absorption lens L3a compared to the high water absorption lens L3b, the optical performance of the finder optical system can be reduced while deterioration of the optical performance of the finder optical system due to changes over time is realized. doing.

  The eyepiece 5 of Example 4 (Numerical Example 4) also has a cross-sectional configuration shown in FIG. FIGS. 7A, 7B, and 7C are aberration diagrams when the viewfinder diopter of the eyepiece 5 is −1 diopter (standard diopter), −3 diopter, and +1 diopter. The third lens unit L3 is composed of an acrylic resin, is composed of the lens L3a on the most object side, and is composed of a polycarbonate resin, is composed of the lens L3b having the thickest central wall, and is composed of an acrylic resin, and is the lens L3c on the most observation side. This is a cemented lens composed of three lenses.

  By configuring the lens L3c with a resin material having a pencil hardness larger than that of the lens L3b, an eyepiece (finder optical system) that is hard to be damaged and has excellent weather resistance can be provided. In addition, since the lens L3a is also formed from a resin material having a high pencil hardness, the lens L3a is not easily damaged during assembly and is easy to handle. In addition, the lens L3b with a low water absorption rate is made thicker than the lens L3c with a high water absorption rate, thereby reducing the deterioration of the optical performance of the finder optical system due to changes over time and increasing the magnification of the finder optical system. doing.

  The eyepiece 5 of Example 5 (Numerical Example 5) is the same as the eyepiece 5 of Example 2 and has the configuration of the cross-sectional view shown in FIG. The numerical values of (6) and (7) are different. 8A, 8 </ b> B, and 8 </ b> C show aberrations when the viewfinder diopter of the eyepiece 5 of the eyepiece 5 of Example 5 is −1 diopter (standard diopter), −3 diopter, and +1 diopter. FIG. The eyepiece 5 of the present embodiment can obtain the same effects as those of the second embodiment.

  The eyepiece 5 of Example 6 (Numerical Example 6) is the same as the cemented lens 5 of Example 2, and has the configuration of the cross-sectional view shown in FIG. The numerical values of (6) and (7) are different. 9A, 9B, and 9C show aberrations when the viewfinder diopter of the eyepiece 5 of the eyepiece 5 of Example 6 is -1 diopter (standard diopter), -3 diopter, and +1 diopter. FIG. The eyepiece 5 of the present embodiment can obtain the same effects as those of the second embodiment.

  The eyepiece 5 of Example 7 (Numerical Example 7) is the same as the cemented lens 5 of Example 2 and has the configuration of the cross-sectional view shown in FIG. The numerical values of (6) and (7) are different. 10A, 10B, and 10C show aberrations when the viewfinder diopter of the eyepiece 5 of the eyepiece 5 of Example 7 is -1 diopter (standard diopter), -3 diopter, and +1 diopter. FIG. The eyepiece 5 of the present embodiment can obtain the same effects as those of the second embodiment.

  FIG. 11 is a cross-sectional view of the photographing optical system of Example 8, and FIG. 12 is an aberration diagram thereof. The photographing optical system includes, in order from the object side to the image side, a first lens group G21 having a positive refractive power, a second lens group G22 having a positive refractive power, and a third lens group G23 having a negative refractive power. Has been. Diopter adjustment is performed by moving the second lens group G22 in the optical axis direction. The first lens group G3 includes a cemented lens obtained by cementing a lens G21a made of acrylic resin and a lens G21b made of styrene resin. The lens G21a is located on the most object side lens (outermost lens) and is exposed to the outside.

  The pencil hardness of G21b made of styrene resin is 2H, and the pencil hardness of lens G21a made of acrylic resin is 3H. By configuring the outermost lens with a resin material having a high pencil hardness, it is possible to provide a photographing lens that is not easily damaged and has excellent weather resistance. In addition, by increasing the center thickness of the lens G21a having a low water absorption rate than the lens G21b having a high water absorption rate, the deterioration of the optical performance of the finder optical system due to changes over time can be reduced and the magnification of the finder optical system can be increased. doing.

  Next, numerical examples corresponding to the respective examples will be shown. In each numerical example, the surface number indicates the order from the focusing screen 3. ri is the radius of curvature of the i-th optical element surface in order from the focusing screen 3 side. r1 (3) means that r1 is the exit surface of the focusing screen 3. r2 means the exit surface (plane) of the exit part 4d. di is the thickness of the i-th optical element and the air interval in order from the focusing screen 3 side. ndi and νdi are respectively the refractive index and Abbe number of the material of the i-th optical element in order from the focusing screen 3 side. r1 corresponds to the matte surface (the surface on which the object image is formed) of the focusing screen 3. r2 is a design dummy surface provided on the object side of the eyepiece 5. In Numerical Examples 1 to 3, r3 to r9, r3 to r10 in Numerical Example 4, and r3 to r7 in Numerical Example 5 are the radii of curvature of the lens surfaces constituting the eyepiece 5. The final surface shows the eye point. In Numerical Example 8, r1 to r7 are the radii of curvature of the lens surfaces r21 to r27 constituting the photographing lens. The final surface shows the imaging surface.

In each numerical example, an asterisk represents an aspherical surface. The aspherical shape has an X axis in the optical axis direction, a Y axis in the direction perpendicular to the optical axis, and the light traveling direction is positive, and R is a paraxial radius of curvature. , K, A4, A6, A8, A10, it is defined by the following equation. Further, the display of “e-0X” means “10 ^−X ”.

  In the numerical examples, the eye point indicates the distance (eye relief) from the final lens surface of the eyepiece to the eye point. Table 1 shows the relationship between the conditional expressions described above and the numerical values in the numerical examples.

(Numerical example 1)
Unit mm
Surface data surface number rd nd vd
1 ∞ 69.81
2 ∞ 0.56
3 -500.481 2.00 1.58306 30.2
4 * 34.314 (variable)
5 * 21.943 5.68 1.53110 56.0
6 -30.825 (variable)
7 * 21.300 6.00 1.57400 33.8
8 * 11.374 3.00 1.49171 57.4
9 * 11.374 23.00
10 (eye point)
Aspheric data 4th surface
K = 0-0000e + 00, A4 = -3-6506e-08, A6 = -1.25194e-07, A8 = 7.58542e-10, A10 = -1.64874e-12
5th page
K = 0-0000e + 00, A4 = -4.31109e-06, A6 = -3-4991e-07, A8 = 1.40490e-09, A10 = -2.48372e-12
7th page
K = 1.28427e + 00, A4 = -8.20943e-05, A6 = 1.94273e-07, A8 = -8.88333e-10, A10 = -6.11573e-12
8th page
K = 0-0000e + 00, A4 = -1.39360e-04, A6 = 2.20539e-07, A8 = -7.74364e-09, A10 = -1.63569e-11
9th page
K = 0-0000e + 00, A4 = -1.39360e-04, A6 = 2.20539e-07, A8 = -7.74364e-09, A10 = -1.63569e-11
Various data diopters (m ^-1 ) +1 -1 -3
Focal length 60.63 63.45 59.78
d 4 3.22 0.78 4.11
d 6 2.89 5.33 2.00

(Numerical example 2)
Unit mm
Surface data surface number rd nd vd
1 ∞ 69.81
2 ∞ 0.66
3 -381.775 2.00 1.58306 30.2
4 * 30.336 (variable)
5 * 21.962 5.65 1.53110 56.0
6 -30.772 (variable)
7 * 21.300 1.00 1.49171 57.4
8 * 21.300 8.63 1.57400 34.0
9 * 11.671 1.00 1.49171 57.4
10 * 11.671 23.00
11 (eye point)
Aspheric data 4th surface
K = 0.00000e + 00, A4 = -5.43282e-06, A6 = -4.48166e-08, A8 = -5.71121e-10, A10 = 3.66982e-12
5th page
K = 0.00000e + 00, A4 = -3.50957e-06, A6 = -2.37138e-07, A8 = 8.92388e-11, A10 = 1.89928e-12
7th page
K = -6.05217e + 00, A4 = 2.86643e-05, A6 = -2.42145e-07, A8 = 2.90402e-09, A10 = -9.27813e-12
8th page
K = -6.05217e + 00, A4 = 2.86643e-05, A6 = -2.42145e-07, A8 = 2.90402e-09, A10 = -9.27813e-12
9th page
K = 0.00000e + 00, A4 = -1.08265e-04, A6 = -9.11182e-08, A8 = -4.87879e-10, A10 = -2.19740e-11
10th page
K = 0.00000e + 00, A4 = -1.08265e-04, A6 = -9.11182e-08, A8 = -4.87879e-10, A10 = -2.19740e-11
Various data diopters (m ^-1 ) +1 -1 -3
Focal length 60.15 64.34 58.87
d 4 2.87 0.97 3.54
d 6 1.54 3.44 0.86

(Numerical Example 3)
Unit mm
Surface data surface number rd nd vd
1 ∞ 69.81
2 ∞ 0.72
3 -500.475 2.00 1.58306 30.2
4 * 34.314 (variable)
5 * 21.888 5.58 1.53110 56.0
6 -30.644 (variable)
7 * 21.300 6.00 1.58306 30.2
8 * 11.370 3.00 1.49171 57.4
9 * 11.370 23.00
10 (eye point)
Aspheric data 4th surface
K = 0-0000e + 00, A4 = -1.36411e-06, A6 = -1-1009e-07, A8 = 5.58861e-10, A10 = -1-4795e-12
5th page
K = 0-0000e + 00, A4 = -6.21045e-06, A6 = -2.88480e-07, A8 = 1.31863e-09, A10 = -2.33381e-12
7th page
K = 1.36806e + 00, A4 = -8.20221e-05, A6 = 1.96062e-07, A8 = -1.23546e-09, A10 = -4.36216e-12
8th page
K = 0-0000e + 00, A4 = -1.38547e-04, A6 = 2.38321e-07, A8 = -9.18345e-09, A10 = -1.80762e-12
9th page
K = 0-0000e + 00, A4 = -1.38547e-04, A6 = 2.38321e-07, A8 = -9.18345e-09, A10 = -1.80762e-12
Various data diopters (m ^-1 ) +1 -1 -3
Focal length 60.65 63.40 59.83
d 4 3.23 0.78 4.12
d 6 2.82 5.26 1.93

(Numerical example 4)
Unit mm
Surface data surface number rd nd vd
1 ∞ 69.81
2 ∞ 0.62
3 -326.673 2.00 1.58306 30.2
4 * 30.162 (variable)
5 * 22.267 5.53 1.53110 56.0
6 -29.805 (variable)
7 * 21.300 1.00 1.49171 57.4
8 * 21.300 8.72 1.58306 30.2
9 * 11.674 1.00 1.49171 57.4
10 * 11.674 23.00
11 (eye point)
Aspheric data 4th surface
K = 0-0000e + 00, A4 = -1.10206e-05, A6 = -6.24753e-08, A8 = 6.60592e-10, A10 = -2-6896e-12
5th page
K = 0-0000e + 00, A4 = -1.47794e-05, A6 = -2.58173e-07, A8 = 1.52181e-09, A10 = -3-8295e-12
7th page
K = -5.39641e + 00, A4 = 2.79588e-05, A6 = -5.38588e-08, A8 = 5-4730e-10, A10 = -7.42979e-12
8th page
K = -5.39641e + 00, A4 = 2.79588e-05, A6 = -5.38588e-08, A8 = 5-4730e-10, A10 = -7.42979e-12
9th page
K = 0-0000e + 00, A4 = -1-5276e-04, A6 = 1-7767e-07, A8 = -6.96525e-09, A10 = -2.49896e-11
10th page
K = 0-0000e + 00, A4 = -1-5276e-04, A6 = 1-7767e-07, A8 = -6.96525e-09, A10 = -2.49896e-11
Various data diopters (m ^-1 ) +1 -1 -3
Focal length 60.14 64.45 58.83
d 4 2.93 1.05 3.59
d 6 1.55 3.43 0.90

(Numerical example 5)
Unit mm
Surface data surface number rd nd vd
1 ∞ 69.81
2 ∞ 0.55
3 -536.554 2.00 1.58306 30.2
4 * 28.703 (variable)
5 * 18.122 5.28 1.53110 56.0
6 -30.149 (variable)
7 * 21.300 1.00 1.49171 57.4
8 * 21.300 6.58 1.57400 34.0
9 * 10.692 1.00 1.49171 57.4
10 * 10.692 23.00
11 (eye point)
Aspheric data 4th surface
K =-0000e + 00, A4 = -3-3146e-05, A6 = 1.39201e-08, A8 = 1.92034e-10, A10 = -5-5202e-14
5th page
K =-0000e + 00, A4 = -4-6648e-05, A6 = -2.63751e-07, A8 = 8.87633e-10, A10 = -1.34339e-12
7th page
K = -6.15465e + 00, A4 = 9.40037e-06, A6 = -6.19753e-08, A8 = 3-5161e-09, A10 = -1.10458e-11
8th page
K = -6.15465e + 00, A4 = 9.40037e-06, A6 = -6.19753e-08, A8 = 3-5161e-09, A10 = -1.10458e-11
9th page
K =-0000e + 00, A4 = -1.65530e-04, A6 = 1.92884e-07, A8 = -2.65371e-09, A10 = -3.15095e-11
10th page
K =-0000e + 00, A4 = -1.65530e-04, A6 = 1.92884e-07, A8 = -2.65371e-09, A10 = -3.15095e-11
Various data diopters (m ^-1 ) +1 -1 -3
Focal length 60.50 63.60 59.53
d 4 2.67 0.67 3.44
d 6 1.27 3.27 0.50

(Numerical example 6)
Unit mm
Surface data surface number rd nd vd
1 ∞ 69.81
2 ∞ 0.55
3 -538.903 2.00 1.58306 30.2
4 * 31.624 (variable)
5 * 18.354 5.25 1.53110 56.0
6 -30.422 (variable)
7 * 21.300 1.00 1.49171 57.4
8 * 21.300 6.32 1.57400 34.0
9 * 10.394 1.00 1.49171 57.4
10 * 10.394 23.00
11 (eye point)
Aspheric data 4th surface
K = 0-0000e + 00, A4 = -3.19026e-05, A6 = 2.52936e-08, A8 = 8.25267e-10, A10 = -3.47354e-12
5th page
K = 0-0000e + 00, A4 = -4.22798e-05, A6 = -2.73716e-07, A8 = 1.92084e-09, A10 = -5.99417e-12
7th page
K = -2.79333e + 00, A4 = -4.51202e-05, A6 = 4.53072e-07, A8 = -2.29722e-09, A10 = 1-5050e-11
8th page
K = -2.79333e + 00, A4 = -4.51202e-05, A6 = 4.53072e-07, A8 = -2.29722e-09, A10 = 1-5050e-11
9th page
K = 0-0000e + 00, A4 = -1.95971e-04, A6 = 7.50172e-07, A8 = -1.83408e-08, A10 = 7.27020e-11
10th page
K = 0-0000e + 00, A4 = -1.95971e-04, A6 = 7.50172e-07, A8 = -1.83408e-08, A10 = 7.27020e-11
Various data diopters (m ^-1 ) +1 -1 -3
Focal length 59.98 61.86 59.41
d 4 2.76 0.50 3.73
d 6 1.46 3.73 0.50

(Numerical example 7)
Unit mm
Surface data surface number rd nd vd
1 ∞ 69.81
2 ∞ 0.56
3 -502.976 2.00 1.58306 30.2
4 * 26.614 (variable)
5 * 20.438 5.21 1.53110 56.0
6 -31.061 (variable)
7 * 21.300 1.00 1.49171 57.4
8 * 21.300 9.81 1.57400 34.0
9 * 11.550 1.00 1.49171 57.4
10 * 11.550 23.00
11 (eye point)
Aspheric data 4th surface
K =-0000e + 00, A4 = -7-9779e-06, A6 = -1-3551e-07, A8 = 7.29837e-11, A10 = 7.69283e-13
5th page
K =-0000e + 00, A4 = 1.86856e-06, A6 = -2.77412e-07, A8 = 2.11200e-10, A10 = 7.90268e-13
7th page
K = -7.29221e + 00, A4 = 3.81112e-05, A6 = -4.82117e-07, A8 = 4.52797e-09, A10 = -1-6468e-11
8th page
K = -7.29221e + 00, A4 = 3.81112e-05, A6 = -4.82117e-07, A8 = 4.52797e-09, A10 = -1-6468e-11
9th page
K =-0000e + 00, A4 = -1.17546e-04, A6 = -1.51021e-07, A8 = 1.84050e-09, A10 = -1.25528e-11
10th page
K =-0000e + 00, A4 = -1.17546e-04, A6 = -1.51021e-07, A8 = 1.84050e-09, A10 = -1.25528e-11
Various data diopters (m ^-1 ) +1 -1 -3
Focal length 58.25 62.57 56.80
d 4 2.48 0.96 3.05
d 6 1.30 2.82 0.73

(Numerical example 8)
Unit mm
Surface data surface number rd nd vd
1 * 1.361 0.20 1.49200 57.4
2 * 1.361 1.05 1.57400 33.8
3 * 2.155 0.70
4 * -218.879 1.14 1.53110 56.0
5 * -2.399 0.39
6 * -3.027 0.60 1.58600 30.0
7 * -5.603 0.30
8 ∞
Aspheric data 1st surface
K = 8.38614e-001 A 4 = -8.40349e-003 A 6 = -6.52207e-002 A 8 = -3.00007e-002
Second side
K = 8.38614e-001 A 4 = -8.40349e-003 A 6 = -6.52207e-002 A 8 = -3.00007e-002
Third side
K = 2.57647e + 000 A 4 = 4.43657e-002 A 6 = 1.49638e-001 A 8 = 3.75693e-003
4th page
K = -6.14315e + 010 A 4 = -1.68298e-001 A 6 = 5.91913e-002 A 8 = 7.32607e-003
5th page
K = 4.29758e-001 A 4 = -6.56940e-002 A 6 = 6.95472e-003 A 8 = 1.85832e-018
6th page
K = -1.10829e-002 A 4 = 8.98127e-004
7th page
K = 8.72556e-001 A 4 = -1.99231e-002
Various data focal length 3.55
F number 2.53
Half angle of view 28.17 °
Statue height 1.90
Total lens length 4.44
The numerical values of the conditional expressions in each example are shown in Table 1 below.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary. For example, the optical apparatus of the present invention is not limited to a digital single lens reflex camera, and may be a digital video camera, a surveillance camera, binoculars, a microscope, or the like. The eyepiece lens and the photographing lens are preferably composed of three groups from the viewpoint of miniaturization, but may be composed of four or more groups. The material of the outermost lens is not limited to acrylic resin.

  The present invention is applicable to applications of optical systems and optical equipment.

L3 ... Third lens group (junction lens), 5 ... Eyepiece lens (optical system)

Claims (10)

An optical system in which a cemented lens obtained by cementing a plurality of lenses made of different resin materials is disposed on the outermost side,
The pencil hardness of the thickest lens material constituting the cemented lens is H1, the pencil hardness of the outermost lens material of the cemented lens is H2, and the center thickness and material of the thickest lens of the central thickness. An optical system characterized by satisfying the following conditional expression where t1 and A are the water absorptivity of the lens and t2 and B are the center thickness of the outermost lens and the water absorptivity of the material.
H1 <H2
1 <B / A <35
1.6 ≦ t1 / t2 <20   The optical system according to claim 1, wherein H2 has a pencil hardness of 3H or more.   The optical system is an eyepiece optical system, and in order from the object side to the observation side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a first lens having a negative refractive power. 2. A three-group configuration comprising three lens groups, wherein the second lens group moves in the optical axis direction when adjusting diopter, and the cemented lens is disposed in the third lens group. Or the optical system of 2. The following conditional expression is satisfied, where N1 is a refractive index of the material of the lens having the thickest central thickness, and N2 is a refractive index of the outermost lens. 2. The optical system according to item 1.
1 <N1 / N2 <1.3 The second lens group includes a single positive lens, and the Abbe number of the positive lens material is νd2, and the Abbe number of the thickest lens material of the cemented lens is νd3. The optical system according to claim 3, wherein the following conditional expression is satisfied.
νd3 <νd2 4. The following conditional expression is satisfied, where d3 is the center thickness of the cemented lens, f1 is the focal length of the first lens group, and f is the focal length of the entire optical system. Or the optical system according to 4;
0.13 <d3 / f <0.21
-1 <f1 / f <-0.7   The optical system according to claim 1, further comprising an erect image forming member that converts an inverted inverted image into an erect image. The optical system is a photographing optical system that forms an optical image of an object,
A first lens group having a positive refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power in order from the object side to the image side; The optical system according to claim 1, wherein a lens is disposed in the first lens group.   An optical apparatus that houses the optical system according to claim 1 and is detachable from a camera body.   An optical apparatus comprising the optical system according to claim 1.