JP2016090693A - Finder optical system and imaging device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a finder optical system that has an entire system downsized even when an image display face is enlarged in the finder optical system to be used with the finder optical system detachably attached to the image display face of an imaging device, and enables an excellent observation of an image to be displayed on the image display face.SOLUTION: Let a length of a short side direction in an effective surface of an image display surface be L, a reflection point closest to the image display surface of reflection points when bottom light of a light flux emitted from an end of the short side direction in the effective surface of the image display surface upon a first reflection surface be a point P, a distance between the image display surface and the point P in an optical axis direction of a finder optical system be M, an optical path length from emission of a light ray from a screen center of the image display surface until the light ray passing the optical axis of the finder optical system and reflected upon the first reflection surface and second reflection surface is incident upon a lens surface apex on an image display surface side of a first lens since from emission of a light ray from a screen center of the image display surface be N, and a focal length of an eyepiece optical system when a diopter is a 0 (zero) diopter be f, each is properly set.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a viewfinder optical system and an image pickup apparatus having the same, and is particularly suitable for observing an image displayed on an image display surface provided in a video camera, a broadcast camera, a still camera, or the like.

  In an imaging device such as a video camera or a still camera, an image display surface represented by a liquid crystal panel or the like is provided on the back side of the device body for shooting moving images and still images and for checking images after shooting. Yes. When observing an image displayed on the image display surface, visibility may be significantly reduced when external light is incident on the image display surface and reflected. Further, at the time of shooting, the photographer may want to recognize a subject with a long object distance and an image display surface with a short object distance at the same time. At this time, the diopter when focusing on both is different. For this reason, it was difficult to observe both well.

  On the other hand, a finder optical system having an eyepiece optical system that is detachably attached to an image display surface has been proposed. This viewfinder optical system can solve the above-mentioned problems, so that photographing can be performed comfortably.

  In this finder optical system, if the diagonal length of the image display surface is 2Y, the viewing angle is 2ω, and the focal length of the entire eyepiece optical system is f, these parameters are Y = f × tan ω. From this equation, if the image display surface is enlarged while securing an arbitrary viewing angle, the focal length of the entire eyepiece optical system also becomes longer. For this reason, a finder optical system that is large enough to be used even when the image display surface is directly viewed increases in size as a whole.

  2. Description of the Related Art Conventionally, a finder optical system is known in which an optical path is bent using two reflecting mirrors to reduce the overall size (Patent Documents 1 and 2). In Patent Document 1, a light beam from an image display surface is reflected by a first reflection surface, and the light beam is totally reflected again by a second reflection surface that is substantially on the same plane as the image display surface, and guided to an eyepiece optical system. A viewfinder optical system (display device) is disclosed. Patent Document 2 discloses a finder optical system in which a light beam from an image display surface is specularly reflected by a first reflection surface and a second reflection surface and guided to an eyepiece optical system.

Japanese Patent Laid-Open No. 10-304228 Japanese Patent Laid-Open No. 11-196302

  The viewfinder optical system that guides the light beam from the image display surface to the observer's pupil through the eyepiece optical system using two reflecting surfaces can be easily reduced in size. However, in order to improve the appearance of the image displayed on the image display surface while reducing the size of the entire system, the position, angle, and configuration of the eyepiece optical system with respect to the size of the image display surface It is important to make appropriate. If these configurations are not appropriate, it is difficult to observe the image displayed on the image display surface satisfactorily while reducing the size of the finder optical system when the image display surface is large.

  For example, when both a total reflection region and a specular reflection region are provided on one reflection surface, the discontinuity of reflectivity may occur at the joint portion between the two reflection surfaces as compared with the reflection surface of the specular reflection region. is there. As a result, the visibility of the viewfinder optical system decreases. Further, if the reflecting surface is configured using a prism, the weight becomes heavy.

  The present invention provides a finder optical system that is detachably attached to an image display surface of an image pickup apparatus, and even when the image display surface is enlarged, the image displayed on the image display surface is favorably reduced while reducing the size of the entire system. An object is to provide a finder optical system that can be observed.

The finder optical system of the present invention is a finder optical system for observing an image displayed on an image display surface, and the finder optical system is sequentially arranged from the image display surface, a first reflection surface, a second reflection surface, An eyepiece optical system, and the eyepiece optical system includes, in order from the image display surface to the observation side, a first lens having a negative refractive power and a second lens having a positive refractive power, and an effective surface of the image display surface L is the length in the short side direction at L, and the image display among the reflection points when the lower ray of the light beam emitted from the end in the short side direction on the effective surface of the image display surface is reflected by the first reflecting surface The reflection point closest to the surface is a point P, the distance between the image display surface and the point P in the optical axis direction of the finder optical system is M, and the light of the finder optical system is emitted from the center of the screen of the image display surface. A ray passing on the axis is the first reflecting surface and the Reflected by the second reflecting surface, the optical path length to be incident on the lens surface vertex of the image display surface side of the first lens N, when the focal length of the ocular optical system when diopter 0 diopter to is f,
1.3 <L / M <13.7
0.58 <N / f <0.79
It is characterized by satisfying the following conditional expression.

  According to the present invention, in a finder optical system that is detachably attached to an image display surface of an imaging apparatus, an image displayed on the image display surface can be reduced while reducing the size of the entire system even when the image display surface is enlarged. A finder optical system that can be observed well is obtained.

Optical sectional view of the finder optical system of the present invention (A), (B), (C) Lens sectional view of the optical system of Numerical Example 1 Aberration diagram of the optical system of Numerical Example 1 in the reference state (A), (B), (C) Lens sectional view of the optical system of Numerical Example 2 Aberration diagram in the reference state of the optical system according to Numerical Example 2. (A), (B), (C) Lens sectional view of the optical system of Numerical Example 3 Aberration diagram in the reference state of the optical system according to Numerical Example 3 (A), (B), (C) Lens sectional view of the optical system of Numerical Example 4 Aberration diagram in the reference state of the optical system according to Numerical Example 4 (A), (B), (C) Lens sectional view of the optical system of Numerical Example 5 Aberration diagram in the reference state of the optical system according to Numerical Example 5 (A), (B), (C) Lens sectional view of the optical system of Numerical Example 6 Aberration diagram in the reference state of the optical system according to Numerical Example 6 (A), (B), (C) Lens sectional view of the optical system of Numerical Example 7 Aberration diagram in the reference state of the optical system according to Numerical Example 7 (A), (B), (C) Lens sectional view of the optical system of Numerical Example 8 Aberration diagram in the reference state of the optical system according to Numerical Example 8. (A), (B), (C) Lens sectional view of the optical system of Numerical Example 9 Aberration diagram in the reference state of the optical system according to Numerical Example 9 Schematic diagram of essential parts when the finder optical system of the present invention is applied to a camera.

  Embodiments of the finder optical system of the present invention will be described below with reference to the drawings. A finder optical system of the present invention is a finder optical system for observing an image displayed on an image display surface, and the finder optical system is a first reflection surface, a second reflection surface, and an eyepiece optical system in order from the image display surface. have. The eyepiece optical system includes, in order from the image display surface to the observation side, a first lens having a negative refractive power and a second lens having a positive refractive power.

  FIG. 1 is an optical sectional view of a finder optical system of the present invention. 2A, 2B, and 2C are optical cross-sectional views at the reference state (−2.0 diopter), +2.5 diopter, and −6.0 diopter of the finder optical system according to the first embodiment of the present invention. is there. FIG. 3 is a diagram showing various aberrations in the reference state of Example 1 of the present invention. 4A, 4B, and 4C are optical cross-sectional views at the reference state (−2.0 diopter), +2.5 diopter, and −6.0 diopter of the finder optical system according to Example 2 of the present invention. is there. FIG. 5 is a diagram showing various aberrations in the reference state of Example 2 of the present invention.

  6A, 6B, and 6C are optical cross-sectional views in the reference state (−2.0 diopter), +2.0 diopter, and −5.5 diopter of the finder optical system according to Example 3 of the present invention. is there. FIG. 7 is a diagram illustrating various aberrations in the reference state according to the third embodiment of the present invention. 8A, 8B, and 8C are optical cross-sectional views at the reference state (−2.0 diopter), +2.0 diopter, and −5.5 diopter of the finder optical system according to Example 4 of the present invention. is there. FIG. 9 is a diagram illustrating various aberrations in the reference state according to the fourth embodiment of the present invention.

  FIGS. 10A, 10B, and 10C are optical cross-sectional views in the reference state (−2.0 diopter), +2.0 diopter, and −5.5 diopter of the finder optical system according to Example 5 of the present invention. is there. FIG. 11 is a diagram illustrating various aberrations in the reference state according to Example 5 of the present invention. 12A, 12B, and 12C are optical cross-sectional views at the reference state (−2.0 diopter), +2.0 diopter, and −5.5 diopter of the finder optical system according to Example 6 of the present invention. is there. FIG. 13 is a diagram illustrating various aberrations in the reference state according to Example 6 of the present invention.

  14A, 14B, and 14C are optical cross-sectional views at the reference state (−2.0 diopter), +2.0 diopter, and −5.5 diopter of the finder optical system according to Example 7 of the present invention. is there. FIG. 15 is a diagram illustrating various aberrations in the reference state according to Example 7 of the present invention. 16A, 16B, and 16C are optical cross-sectional views at the reference state (−2.0 diopter), +2.0 diopter, and −5.5 diopter of the finder optical system according to Example 8 of the present invention. is there. FIG. 17 is a diagram illustrating various aberrations in the reference state according to Example 8 of the present invention.

  18A, 18B, and 18C are optical cross-sectional views at the reference state (−2.0 diopter), +2.0 diopter, and −5.5 diopter of the finder optical system according to Example 9 of the present invention. is there. FIG. 19 is a diagram illustrating various aberrations in the reference state according to Example 9 of the present invention. FIG. 20 is a schematic view of the main part of the imaging apparatus of the present invention.

  In the optical cross-sectional view (vertical cross-sectional view) of the finder optical system shown in FIG. The image display surface 2 has a rectangular shape, and FIG. 1 shows the rectangular direction of the image display surface 2. Ref1 is a first reflecting surface, and Ref2 is a second reflecting surface. OE is an eyepiece optical system. EP is an eye point and corresponds to the observation position of the observer. Oa is the optical axis of the finder optical system. The optical axis Oa corresponds to a light beam that exits the center 2a of the image display surface 2 perpendicularly and enters the center Epa of the eye point EP perpendicularly.

  θ1 is an angle formed by the image display surface 2 and the first reflection surface Ref1. θ2 is an angle formed by the image display surface 2 and the second reflection surface Ref2. A plate for protecting the image display surface 2 and the lens may be provided between the image display surface 2 and the eyepiece optical system OE or between the eyepiece optical system OE and the eye point EP. Further, the position of the eye point EP in the optical axis direction may be moved in the optical axis direction as long as the light rays from the outermost periphery of the image display surface 2 pass through the observer's pupil.

  In the spherical aberration diagram, d is d-line and g is g-line. In the astigmatism diagram, M is a meridional image plane, and S is a sagittal image plane. In the lateral chromatic aberration, g is a g-line. Y is the image height on the image display surface.

  The imaging device in FIG. 20 will be described. In FIG. 20, reference numeral 1 denotes a camera body of the imaging apparatus. Reference numeral 2 denotes an image display surface of the image pickup apparatus, on which an image picked up by an image pickup optical system in the camera body 1 is displayed. Reference numeral 3 denotes a finder optical system for observing a subject image (image information) displayed on the image display element 2 of the present invention. The image display element 2 is configured by a liquid crystal panel or the like. Reference numeral 4 denotes a first holding frame, and a first reflecting mirror Ref1 shown in FIG. Reference numeral 5 denotes a second holding frame, and a second reflecting mirror Ref2 shown in FIG. Reference numeral 6 denotes a lens barrel. The eyepiece optical system OE shown in FIG. 1 is housed in the lens barrel 6.

  In the finder optical system of the present invention, the subject image displayed on the image display surface 2 is observed by being applied to the image display surface of an imaging device such as a video camera.

  In the finder optical system of the present embodiment, the images displayed on the image display surface 2 are observed from the eye point EP through the first reflecting surface Ref1, the second reflecting surface Ref2, and the eyepiece optical system L in the order in which the light beams pass. . The eyepiece optical system OE includes a first lens G1 having a negative refractive power and a second lens G2 having a positive refractive power for diopter adjustment in order from the image display surface 1 to the eye point EP side. The entire system of the eyepiece optical system OE has a positive refractive power. In the eyepiece optical system OE, the more lenses having positive refractive power, the light can be gradually condensed by each lens, and the occurrence of higher order aberrations can be reduced.

  However, it is difficult to correct various aberrations such as longitudinal chromatic aberration and lateral chromatic aberration only with a lens having positive refractive power. For this reason, chromatic aberration is corrected using a lens having negative refractive power. Moreover, the pupil side principal point position is moved to the pupil side by setting the power arrangement from the image display surface 2 side to the first lens G1 having a negative refractive power and the second lens G2 having a positive refractive power. This shortens the optical path length from the image display surface 2 to the first lens G1.

  In the finder optical system of the present invention, the length of the effective surface of the image display surface 2 in the short side direction is L, and the lower ray of the light beam emitted from the end of the effective surface of the image display surface 2 in the short side direction is the first reflecting surface. Of the reflection points when reflected by Ref1, the reflection point closest to the image display surface 2 is defined as a point P.

Let M be the distance between the image display surface 2 and the point P in the optical axis direction of the finder optical system. A light beam emitted from the center of the screen of the image display surface 2 and passing on the optical axis of the finder optical system is reflected by the first reflection surface Ref1 and the second reflection surface Ref2, and reaches the vertex of the lens surface on the image display surface side of the first lens G1. Let N be the optical path length until incidence. Let f be the focal length of the eyepiece optical system OE when the diopter is 0 diopter. At this time,
1.3 <L / M <13.7 (1)
0.58 <N / f <0.79 (2)
This satisfies the conditional expression

  Here, the lower ray of the light beam emitted from one point on the image display surface 2 is between the image display surface 2 and the first reflecting surface Ref1 among the light rays emitted from the image display surface 2 and incident on the pupil EP of the observer. The light beam farthest from the optical axis Oa. The light path length N is that the light beam on the optical axis Oa emitted from the screen center 2a of the image display surface 2 is reflected by the reflection point Ref1a of the first reflection surface Ref1. The distance from the second reflecting surface Ref2 to the lens surface vertex G1a on the image display surface side (incident side) after being reflected by the second reflecting surface Ref2a.

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (1) defines the length of the effective surface of the image display surface 2 in the short side direction and the distance between the image display surface 2 and the first reflecting surface Ref1. When the light beam emitted from the image display surface 2 is reflected by the first reflection surface Ref1, it is reflected in the short side direction on the effective surface of the image display surface 2 to reduce the entire finder optical system. If the effective surface of the image display surface 2 is a square, it may be reflected in the direction of either side.

  In addition, since the screen size is about 2 to 5 inches in the viewfinder optical system in which an image display surface mounted on a video camera or a still camera is viewed through the eyepiece optical system OE, it is necessary to increase the viewing angle with the eyepiece optical system OE. Is low. For this reason, the effective diameter of the eyepiece optical system OE is smaller than that of the image display surface 2, and between the image display surface 2 and the first lens G1, the closer to the first lens G1, the smaller the effective beam diameter.

  Therefore, when the upper limit of conditional expression (1) is exceeded, the first reflective surface Ref1 approaches the image display surface 2, so that the effective area of the first reflective surface Ref1 increases, and it is difficult to reduce the size of the entire system. On the contrary, when the lower limit is exceeded, the length in the direction perpendicular to the image display surface 2 becomes longer than the length of the image display surface 2, so that the viewfinder optical system becomes large.

  Conditional expression (2) defines the ratio of the optical path length from the image display surface 2 to the first lens G1 and the focal length of the entire eyepiece optical system OE when the finder diopter is 0 dpt. When the upper limit value of conditional expression (2) is exceeded, the pupil-side principal point position of the eyepiece optical system OE moves to the image display surface 2 side. As a result, the optical path length from the image display surface 2 to the first lens G1 becomes long, and the viewfinder optical system becomes large. On the other hand, when the value falls below the lower limit, coma and distortion increase. More preferably, the numerical ranges of conditional expressions (1) and (2) are set as follows.

1.4 <L / M <13.1 (1a)
0.58 <N / f <0.77 (2a)
In the finder optical system of the present invention, it is more preferable to satisfy one or more of the following conditional expressions. An angle formed by the image display surface 2 and the second reflection surface Ref2 in a vertical section formed by the optical axis Oa (component in the optical axis direction) of the finder optical system 3 and the short side direction of the image display surface 2 is θ2. To do. The second lens G2 moves during diopter adjustment, and the focal length of the second lens G2 is fp. At this time, one or more of the following conditional expressions should be satisfied.

9 ° <θ2 <80 ° (3)
0.10 <fp / f <0.37 (4)
Here, the angle θ2 corresponds to an angle formed between a perpendicular to the optical axis passing through the eyepiece optical system OE and the reflecting surface of the second reflecting mirror Ref2.

  Conditional expression (3) appropriately sets the arrangement angle of the second reflecting surface Ref2. Similar to the first reflecting surface Ref1, the entire viewfinder optical system is miniaturized by reflecting the light emitted from the image display surface 2 in the short side direction of the image display surface 2. If the upper limit value of conditional expression (3) is exceeded, the light beam reflected by the first reflecting surface Ref1 may be vignetted by the first lens G1. On the contrary, if the lower limit is exceeded, the effective area of the second reflecting surface Ref2 becomes large, and the viewfinder optical system becomes large.

  In the finder optical system of the present invention, the diopter adjustment is performed by moving the second lens G2 having a positive refractive power in the optical axis direction.

  Conditional expression (4) relates to the focal length of the first lens G1. Conditional expression (4) defines the ratio of the focal lengths of the second lens G2 having a positive refractive power used for diopter adjustment and the entire eyepiece optical system OE when the diopter is 0 diopter (dpt). If the upper limit value of conditional expression (4) is exceeded, the amount of movement of the second lens G2 having a positive refractive power for diopter adjustment on the optical axis increases, and the entire finder optical system becomes large. On the other hand, if the lower limit is not reached, the amount of variation in lateral chromatic aberration increases during diopter adjustment. More preferably, the numerical ranges of conditional expressions (3) and (4) should be set as follows.

9.5 ° <θ2 <74.6 ° (3a)
0.11 <fp / f <0.35 (4a)
As described above, according to the present invention, it is possible to obtain a finder optical system in which the entire system is small even when attached to a large image display surface.

  The finder optical system of the present invention preferably has the following configuration. The angle component in the long side direction of the second reflecting surface Ref2 is desirably 9 ° or less with respect to the image display surface 2. Similarly, the angle component in the long side direction of the first reflecting surface Ref1 is desirably 9 ° or less. In the finder optical system of the present invention, it is desirable that the first reflecting surface Ref1 does not re-reflect the light beam that has been reflected once.

  The configuration in which the light beam from the image display surface 2 is reflected by the first reflecting surface Ref1, reflected by the second reflecting surface Ref2, and incident on the first reflecting surface Ref1 is a prism using total reflection, or the first reflecting surface. This is a case where Ref1 is a half mirror. When a prism is used, the weight increases and the configuration becomes complicated. Further, when a half mirror is used, the amount of light reaching the pupil is reduced, which is not good.

  In the finder optical system of the present invention, it is desirable that each lens constituting the eyepiece optical system OE has at least one aspherical surface. In order to reduce the size of the finder optical system, it is desirable to reduce the number of lenses as much as possible. In order to reduce the number of lenses, it is indispensable to correct various aberrations such as coma, distortion, and higher order aberrations. If at least one aspheric surface is used for each lens, it becomes easy to satisfactorily correct these various aberrations while reducing the size.

  The viewfinder optical system of the present invention preferably has a diopter adjustment range of −6.5 to +3.0 (1 / m). When the above range is exceeded, the amount of movement of the diopter correction lens by diopter adjustment becomes large, and the entire finder optical system becomes large.

  Numerical examples 1 to 9 corresponding to the first to ninth embodiments of the present invention will be described below. In the numerical example, ri is the radius of curvature of the i-th surface in order from the image display surface 2 side, di is the distance between the i-th surface and the i + 1-th surface (lens thickness or air space), and ndi and νdi are The refractive index and Abbe number of the material of the i-th lens, respectively. Θi is an angle formed by the i-th reflective surface and the short-side direction of the image display surface 2 in order from the image display surface 2 side.

  r1 and r2 are a light incident surface and a light emitting surface of an optical member (glass member) constituting the image display surface. r3 corresponds to the first reflecting surface, and r4 corresponds to the second reflecting surface. r5 and r6 correspond to the first lens, and r7 and r8 correspond to the second lens. The aspherical shape is the X axis in the optical axis direction, the h axis perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, k is the cone coefficient, and the aspheric coefficient is A4, A6, A8. When

It is expressed by the following formula. Further, for example, the display of “e-Z” means “10 ^−Z ”. Table 1 shows the relationship between the above-described conditional expressions and numerical examples.

[Numerical Example 1]
Unit mm

Surface data surface number rd nd νd θ
1 ∞ 2.41 1.51633 64.1
2 ∞ 22.80
3 ∞ 37.80 36.8
4 ∞ 21.6 36.8
5 * -59.853 3.00 1.49171 57.4
6 * 18.325 (variable)
7 * 21.804 8.00 1.49171 57.4
8 * -68.964 (variable)
9 (eye point)

Aspheric data 5th surface
K = 7.89011e + 000

6th page
K = -1.39338e + 000

7th page
K = -1.10848e + 000 A 4 = -7.03741e-006 A 6 = -1.82246e-008 A 8 = -8.54075e-011

8th page
K = -7.78002e + 000 A 4 = -1.25 120e-005 A 6 = -2.11890e-008

Various data diopters [diopter] -2.0 +2.5 -6.0 0
Focal length 210.95 96.51 -3552668 139.90
d 6 9.37 14.86 4.73 11.72
d 8 20.41 14.92 25.04 18.06

[Numerical Example 2]
Unit mm

Surface data surface number rd nd νd θ
1 ∞ 2.41 1.51633 64.1
2 ∞ 21.30
3 ∞ 37.60 36.8
4 ∞ 23.40 36.8
5 * -59.853 3.00 1.49171 57.4
6 * 18.325 (variable)
7 * 21.804 8.00 1.49171 57.4
8 * -68.964 (variable)
9 (eye point)

Aspheric data 5th surface
K = 7.89011e + 000

6th page
K = -1.39338e + 000

7th page
K = -1.10848e + 000 A 4 = -7.03741e-006 A 6 = -1.82246e-008 A 8 = -8.54075e-011

8th page
K = -7.78002e + 000 A 4 = -1.25 120e-005 A 6 = -2.11890e-008

Various data diopters [diopter] -2.0 +2.5 -6.0 0
Focal length 210.95 96.51 -3552668 139.90
d 6 9.37 14.86 4.73 11.72
d 8 20.41 14.92 25.04 18.06

[Numerical Example 3]
Unit mm

Surface data surface number rd nd νd θ
1 ∞ 2.41 1.51633 64.1
2 ∞ 17.40
3 ∞ 31.70 40.8
4 ∞ 19.70 40.8
5 * -47.419 1.30 1.53110 55.9
6 * 19.105 (variable)
7 * 19.748 6.92 1.49171 57.4
8 * -50.165 (variable)
9 (eye point)

Aspheric data 5th surface
K = 2.37792e + 000

6th page
K = -1.71109e + 000

7th page
K = -1.05549e + 000 A 4 = -7.00933e-006 A 6 = -2.38559e-008 A 8 = 7.69450e-012

8th page
K = -1.45377e + 001 A 4 = -1.44953e-005 A 6 = 5.13951e-010

Various data diopters [diopter] -2.0 +2.0 -5.5 0
Focal length 152.88 88.99 404.98 112.84
d 6 7.69 11.25 4.60 9.45
d 8 22.09 18.53 25.18 20.33

[Numerical Example 4]
Unit mm

Surface data surface number rd nd νd θ
1 ∞ 2.00 1.51633 64.1
2 ∞ 41.10
3 ∞ 55.10 28.3
4 ∞ 37.40 28.3
5 * -45.115 1.30 1.49171 57.4
6 * 40.146 (variable)
7 * 28.420 5.00 1.49171 57.4
8 * -90.897 (variable)
9 (eye point)

Aspheric data 5th surface
K = -5.21229e-001

6th page
K = -2.93125e + 000

7th page
K = -9.74935e-001 A 4 = -7.84453e-006 A 6 = -4.39117e-008 A 8 = 1.85242e-011

8th page
K = -5.92859e + 001 A 4 = -1.77178e-005 A 6 = -5.17300e-009

Various data diopters [diopter] -2.0 +2.0 -5.5 0
Focal length 294.82 131.80 17750.62 185.46
d 6 6.95 15.01 0.55 12.74
d 8 22.82 14.77 29.22 17.03

[Numerical Example 5]
Unit mm

Surface data surface number rd nd νd θ
1 ∞ 2.30 1.51633 64.1
2 ∞ 34.40
3 ∞ 63.40 36.0
4 ∞ 45.90 36.0
5 * -61.635 1.28 1.58313 59.4
6 * 50.265 (variable)
7 * 35.873 6.16 1.49171 57.4
8 * -74.484 (variable)
9 (eye point)

Aspheric data 5th surface
K = 9.11587e-001

6th page
K = -5.28332e + 000

7th page
K = -1.07285e + 000 A 4 = -8.13855e-006 A 6 = -4.73423e-008 A 8 = 1.01343e-011

8th page
K = -4.25892e + 001 A 4 = -1.91998e-005 A 6 = -1.18094e-008

Various data diopters [diopter] -2.0 +2.0 -5.3 0
Focal length 348.83 139.46 -3507.81 204.69
d 6 7.95 18.16 0.48 12.74
d 8 21.82 11.61 29.30 17.03

[Numerical Example 6]
Unit mm

Surface data surface number rd nd νd θ
1 ∞ 2.41 1.51633 64.1
2 ∞ 31.20
3 ∞ 37.90 25.9
4 ∞ 33.60 25.9
5 * -23.950 1.31 1.53110 55.9
6 * 12.840 (variable)
7 * 14.357 6.04 1.49 171 57.4
8 * -29.066 (variable)
9 (eye point)

Aspheric data 5th surface
K = -2.45656e + 000

6th page
K = -1.61137e + 000

7th page
K = -1.16303e + 000 A 4 = -1.01256e-005 A 6 = -5.32194e-008 A 8 = 1.06224e-010

8th page
K = -7.95896e + 000 A 4 = -1.71346e-005 A 6 = 3.04453e-008

Various data diopters [diopter] -2.0 +2.0 -5.5 0
Focal length 275.75 112.28 -749.02 158.66
d 6 4.39 6.07 2.81 5.25
d 8 25.38 23.70 26.96 24.53

[Numerical Example 7]
Unit mm

Surface data surface number rd nd νd θ
1 ∞ 2.41 1.51633 64.1
2 ∞ 22.80
3 ∞ 37.80 36.8
4 ∞ 21.60 36.8
5 * -57.093 2.00 1.49171 57.4
6 * 21.463 4.00
7 ∞ 2.00 1.49171 57.4
8 * 123.667 (variable)
9 * 21.576 5.49 1.49171 57.4
10 * -68.029 (variable)
11 (eye point)

Aspheric data 5th surface
K = -1.04412e + 001

6th page
K = -7.00585e-001

8th page
K = 3.98218e + 001

9th page
K = -8.52004e-001 A 4 = 7.57279e-007 A 6 = -5.43059e-008 A 8 = 1.49293e-010

10th page
K = -4.72840e + 001 A 4 = -1.46497e-005 A 6 = 2.03799e-008

Various data diopters [diopter] -2.0 +2.0 -5.5 0
Focal length 213.12 103.33 2432.77 104.03
d 8 5.09 9.73 1.10 7.37
d10 24.69 20.04 28.68 22.41

[Numerical Example 8]
Unit mm

Surface data surface number rd nd νd θ
1 ∞ 2.41 1.51633 64.1
2 ∞ 31.20
3 ∞ 50.90 30.0
4 ∞ 20.60 10.0
5 * -23.950 1.31 1.53110 55.9
6 * 12.840 (variable)
7 * 14.357 6.04 1.49 171 57.4
8 * -29.066 (variable)
9 (eye point)

Aspheric data 5th surface
K = -2.45656e + 000

6th page
K = -1.61137e + 000

7th page
K = -1.16303e + 000 A 4 = -1.01256e-005 A 6 = -5.32194e-008 A 8 = 1.06224e-010

8th page
K = -7.95896e + 000 A 4 = -1.71346e-005 A 6 = 3.04453e-008

Various data diopters [diopter] -2.0 +2.0 -5.5
Focal length 211.26 103.23 1689.15
d 6 4.39 6.07 2.81
d 8 25.38 23.70 26.96

[Numerical Example 9]
Unit mm

Surface data surface number rd nd νd θ
1 ∞ 2.41 1.51633 64.1
2 ∞ 31.20
3 ∞ 37.90 48.0
4 ∞ 33.60 71.0
5 * -23.950 1.31 1.53110 55.9
6 * 12.840 (variable)
7 * 14.357 6.04 1.49 171 57.4
8 * -29.066 (variable)
9 (eye point)

Aspheric data 5th surface
K = -2.45656e + 000

6th page
K = -1.61137e + 000

7th page
K = -1.16303e + 000 A 4 = -1.01256e-005 A 6 = -5.32194e-008 A 8 = 1.06224e-010

8th page
K = -7.95896e + 000 A 4 = -1.71346e-005 A 6 = 3.04453e-008

Various data diopters [diopter] -2.0 +2.0 -5.5
Focal length 2740.75 112.28 -749.02
d 6 4.39 6.07 2.81
d 8 25.38 23.70 26.96


Table 1 shows the relationship between the above-described conditional expressions and various numerical values in the numerical examples.

DESCRIPTION OF SYMBOLS 1 Image pick-up apparatus main body 2 Image display surface 3 Finder optical system Ref1 1st reflective surface Ref2 2nd reflective surface OE Eyepiece optical system G1 1st lens G2 2nd lens EP Eye point

Claims (5)

A finder optical system for observing an image displayed on an image display surface,
The finder optical system has a first reflecting surface, a second reflecting surface, and an eyepiece optical system in order from the image display surface, and the eyepiece optical system has a negative refractive power in order from the image display surface to the observation side. One lens, a second lens with positive refractive power,
The length of the effective side of the image display surface in the short side direction is L, and the reflection when the lower light beam emitted from the end of the effective side of the image display surface in the short side direction is reflected by the first reflection surface Out of the points, the reflection point closest to the image display surface is point P, the distance between the image display surface and the point P in the optical axis direction of the viewfinder optical system is M, and the point is emitted from the center of the screen of the image display surface. The optical path length until the light beam passing on the optical axis of the finder optical system is reflected by the first reflecting surface and the second reflecting surface and enters the vertex of the lens surface on the image display surface side of the first lens is expressed as N. When the focal length of the eyepiece optical system when the diopter is 0 diopter is f,
1.3 <L / M <13.7
0.58 <N / f <0.79
A finder optical system characterized by satisfying the following conditional expression: When the angle formed by the image display surface and the second reflection surface in a vertical cross section including a component in the optical axis direction of the finder optical system and a component in the short side direction of the image display surface is θ2,
9 ° <θ2 <80 °
The finder optical system according to claim 1, wherein the following conditional expression is satisfied. When the diopter adjustment, the second lens moves, and when the focal length of the second lens is fp,
0.10 <fp / f <0.37
The finder optical system according to claim 1, wherein the following conditional expression is satisfied.   The viewfinder optical system according to any one of claims 1 to 3, wherein the eyepiece optical system performs diopter adjustment in a range of -6.5 to +3.0 (1 / m).   An image display surface for displaying an image formed by an imaging optical system, and the finder optical system according to any one of claims 1 to 4 for observing an image displayed on the image display surface. An imaging device.