JP2017021310A - Viewfinder optical system and imaging apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compact finder optical system capable of clearly observing both a subject image formed on a focal plate and display information displayed on a display body in the same field of view with a wide viewing angle. An observation optical system that guides a light beam based on a subject image formed on a predetermined surface to an eyepiece lens by passing it through an erect image forming member and two optical surfaces inclined with respect to an optical axis. And a display optical system that reflects the light beam from the first display body provided in the vicinity of the erect image forming member on two optical surfaces and guides the light beam to the eyepiece lens. In the finder optical system for observing the subject image and the display information displayed on the first display body in the same field of view, the display optical system is the first lens having a positive refractive force and light incident in order from the first display body to the observation side. It has an optical prism having an internal reflecting surface that reflects light incident from the surface and emits it from the light emitting surface, and a second lens having a positive refractive force. [Selection diagram] Fig. 1

Description

  The present invention provides a method for observing both a subject image formed on a focusing screen and display information displayed on a display in the same field of view through a common eyepiece optical system in a finder optical system used in a single-lens reflex camera or the like. Is preferred.

  Conventionally, as a finder optical system used in a single-lens reflex camera, display information such as a distance measurement position displayed on a display body is superimposed on a subject image formed on a focusing screen by a photographing lens. A finder optical system in which both are observed in the same field of view is known (Patent Documents 1 and 2).

  In Patent Document 1, a prism including a half mirror or a dichroic mirror is arranged between a pentaprism (an upright image forming member) and an eyepiece optical system. A viewfinder system is disclosed in which a distance measuring point frame displayed on a display body is superimposed on a subject image formed on a focusing screen via a prism and both are observed in the same field of view. In Patent Document 2, a light beam from display information displayed on a display body is guided into the pentaprism from the side surface of the subject of the pentaprism using an optical path combining member. A viewfinder optical system is disclosed in which both the subject image formed on the focusing screen and the display information displayed on the display body are superimposed to observe both in the same field of view.

Japanese Patent Laid-Open No. 11-237659 JP 2009-3209 A

  In a finder optical system that observes both the subject image formed on the focusing screen and the display information displayed on the display body in the same field of view, when the display range of the display body is expanded, for example, the viewing angle of the display optical system is 15 degrees or more. If it becomes wider, the optical surface that divides the optical path becomes larger. As a result, the display optical system becomes higher in the height direction, and the viewfinder optical system becomes larger.

  In addition, various aberrations such as astigmatism, field curvature, distortion, etc. are generated from the display optical system, and the resolution is reduced when observing the display information, making clear observation difficult. The method of dividing the optical path by arranging an optical surface inclined with respect to the finder optical axis in the finder optical path makes it easy to reduce the size of the finder optical system. However, in order to display the display information of the display body on the subject image formed on the focusing screen and observe both in the same field of view, it is necessary to appropriately set the configuration of the display optical system.

  An object of the present invention is to provide a small finder optical system capable of observing both a subject image formed on a focusing screen and display information displayed on a display body with a wide viewing angle and a clear view in the same field of view. .

The finder optical system of the present invention guides a light beam based on a subject image formed on a predetermined surface to an eyepiece through an erect image forming member and two optical surfaces inclined with respect to the optical axis. An observation optical system, and a display optical system that reflects the light beam from the first display body provided in the vicinity of the erect image forming member by the two optical surfaces and guides it to the eyepiece lens, In the finder optical system for observing the subject image and the display information displayed on the first display body by the observation optical system and the display optical system in the same field of view,
The display optical system includes, in order from the first display body to the observation side, a first lens having a positive refractive power, and an optical prism having an inner reflection surface that reflects a light beam incident from a light incident surface and emits the light from the light emission surface. And a second lens having a positive refractive power.

  According to the present invention, it is possible to obtain a small finder optical system capable of clearly observing both a subject image formed on a focusing screen and display information displayed on a display body with a wide viewing angle and the same visual field.

Schematic of an imaging apparatus provided with a finder optical system according to each embodiment of the present invention The perspective view which shows the structure of the finder optical system which concerns on each Example of this invention. Display example of display information by viewfinder optical system according to each embodiment of the present invention FIG. 3 is a development view along the optical axis of the observation optical system according to Example 1 of the present invention. Aberration diagrams of the observation optical system according to Example 1 of the present invention. FIG. 3 is a development view along the optical axis of the display optical system according to the first embodiment of the present invention. Aberration diagram of the display optical system according to Example 1 of the present invention. FIG. 5 is a development view along the optical axis of the display optical system according to the second embodiment of the present invention. Aberration diagram of display optical system according to Embodiment 2 of the present invention FIG. 6 is a development view along the optical axis of a display optical system according to Example 3 of the present invention. Aberration diagram of display optical system according to Embodiment 3 of the present invention FIG. 5 is a development view along the optical axis of the observation optical system according to Example 4 of the present invention. Aberration diagrams of the observation optical system according to Example 4 of the present invention. FIG. 4 is a development view along the optical axis of a display optical system according to Example 4 of the present invention. Aberration diagram of display optical system according to Embodiment 4 of the present invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the finder optical system of the present invention, a light beam based on a subject image formed on a predetermined surface such as a focusing screen by an imaging optical system passes through an erect image forming member and two optical surfaces inclined with respect to the optical axis. And an observation optical system for guiding light to the eyepiece. And a display optical system that reflects the light beam from the first display body provided in the vicinity of the erect image forming member by two optical surfaces and guides it to the eyepiece. Then, the subject image and the display information displayed on the first display body are observed in the same visual field by the observation optical system and the display optical system.

  FIG. 1 is a schematic diagram of a main part of an image pickup apparatus including a finder optical system according to each embodiment of the present invention. FIG. 2 is a schematic view of FIG. 1 as a bird's eye view of the viewfinder optical system from the upper right part of the observer's eye. In the imaging apparatus shown in FIG. 1, a subject image is formed on a focusing screen (predetermined surface) 3 via a quick return mirror 2 by an imaging optical system 1. When picking up a subject image, the quick return mirror 2 rotates and a subject image is formed on the image pickup device arranged on the image plane IP. Then, the light is received by the image sensor.

  The finder optical system of this embodiment has an observation optical system and a display optical system. Among these, the optical path of the observation optical system is as follows. The subject image formed by the photographic lens 1 passes through the movable mirror 2 and is formed on the diffusion surface (predetermined surface) of the focusing screen 3. A light beam based on a subject image formed on a predetermined surface passes through an erect image forming member 5 including a condenser lens 4 and a penta roof prism. Then, it passes through the prism (transparent member) 6 having two optical surfaces 6c and 6b inclined in different directions with respect to the optical axis Fa of the observation optical system and the eyepiece optical system 7 to reach the observer's eye (pupil) Ea. . Here, the optical surface 6c is a first optical surface, and the optical surface 6b is a second optical surface.

  In this embodiment, each member such as the focusing screen 3, the condenser lens 4, the erect image forming member 5, the prism (transparent member) 6, and the eyepiece optical system 7 constitutes an observation optical system. The second display body 12 may be disposed in the vicinity of the focusing screen 3 and the display information displayed on the second display body 12 may be observed in the same field of view as the subject image formed on the focusing screen 3. Fa is the optical axis of the observation optical system. The optical path of the display optical system constituting a part of the finder optical system is as follows.

  The luminous flux from the display information displayed on the display body 8 disposed in the vicinity of the erect image forming member 5 passes through the first lens 9, the optical prism 10, and the second lens 11, and the optical surface (light) of the prism 6. Incident surface) 6a is transmitted. Thereafter, the light is reflected in the order of two optical surfaces (second optical surface) 6b and optical surface (first optical surface) 6c inclined in different directions with respect to the optical axis Fa of the observation optical system, and then transmitted through the optical surface 6b. Then, the eye reaches the observer's eye (pupil) Ea through the eyepiece optical system 7.

  In this embodiment, each member such as the display body 8, the first lens 9, the optical prism 10, the second lens 11, the prism 6, the eyepiece optical system 7, and the like constitute a display optical system. Fb is the optical axis of the display optical system. In this embodiment, the diopter of the second display body 12 of the observation optical system and the diopter of the display information of the first display body 8 of the display optical system are the same.

  The prism body 6 has an incident surface 6a on which a light beam from the display optical system is incident, and two optical surfaces 6b and 6c inclined in different directions with respect to the optical axis Fa of the observation optical system. The optical surface 6b is constituted by a total reflection surface that totally reflects a light beam incident from the incident surface 6a or a dichroic surface that reflects a light beam in a specific wavelength region. The optical surface 6c is composed of a half mirror or a dichroic surface that reflects a light beam in a specific wavelength region.

  In this embodiment, at least one of the two optical surfaces 6b and 6c is a half mirror or a dichroic mirror. The optical path when the optical surface 6c of the prism body 6 is constituted by a dichroic mirror that reflects a specific wavelength region of visible light (for example, 650 nm or more) and transmits the remaining visible light is as follows. At this time, among the light beams from the focusing screen 3 as the observation optical system and emitted from the erect image forming member 5, most of the visible light (for example, 650 nm or less) is the optical surface 6c of the prism body 6, the optical surface The light enters the eyepiece 7 that has passed through 6b and is used for observing the subject image.

  On the other hand, the light beam from the display information of the display body 8 as a display optical system is incident from the light incident surface 6a of the prism body 6 and totally reflected by the optical surface 6b. A specific wavelength region of visible light (for example, 650 nm or more) out of the totally reflected light beam is incident on the eyepiece 7 which is reflected by the optical surface 6c and transmitted through the optical surface 6b, and is used for observing the display body 8.

  The optical path when the optical surface 6c of the prism body 6 is composed of a half mirror is as follows. At this time, a part of the light beam from the focusing screen 3 as an observation optical system and emitted from the erecting image forming member 5 is transmitted through the optical surface 6 c and then transmitted through the optical surface 6 b to the eyepiece 7. Incident light is used to observe the subject image. The light beam from the display body 8 as a display optical system is incident from the light incident surface 6a of the prism body 6, is totally reflected by the optical surface 6b, and a part of the totally reflected light beam is reflected by the optical surface 6c, and then the optical surface. 6 b passes through the eyepiece 7 and is used for observing the display body 8.

  A dichroic mirror in which the wavelength range of light reflected by the optical surface 6b constituting a part of the prism 6 differs depending on the incident angle, the optical surface 6c reflects a specific wavelength range of visible light (for example, 650 nm or more), and the remaining visible light May be constituted by a dichroic mirror that transmits light. At this time, a specific wavelength region of visible light (for example, 650 nm or more) out of the light flux from the display body 8 is reflected by the optical surface 6b and the optical surface 6c, and then transmitted by the optical surface 6b. On the other hand, most of the visible light from the focusing screen 3 (for example, 650 nm or less) passes through the optical surface 6b and the optical surface 6c. As a result, it becomes easy to keep the finder optical system bright.

  FIG. 3A shows a case where the first display body 8 is displayed as a red distance measuring frame 13 so as to be superimposed on the subject image 20, and the visibility of both the subject image 20 and the distance measuring frame 13 is good. FIG. 3B shows an information body 14 such as various menus displayed on the first display body 8 when the optical surface 6c is used as a half mirror and the optical surface 6b is used as a total reflection surface. 14 shows a case where observation is performed with both of them superimposed.

  The optical prism 10 constituting a part of the display optical system has one reflecting surface 10a inside, and internally reflects the light beam from the display body 8. The display 8 and the first lens 9 are disposed in the vicinity of the reflecting surface 5a of the erect image forming member 5. As a result, the height of the finder optical system is suppressed, and further, the display body 8 and other parts of the camera (not shown) such as an accessory shoe interfere with each other to reduce the size of the camera in the height direction. Yes.

  FIG. 4 is a lens cross-sectional view when the optical path of the observation optical system of Example 1 is developed. FIGS. 5A, 5B, and 5C are aberration diagrams of the observation optical system of Example 1 at -1 dpt (diopter), -3 dpt, and 1 dpt. 6 is a lens cross-sectional view when the optical path of the display optical system of Example 1 is developed. FIGS. 7A, 7B, and 7C are aberration diagrams of the display optical system of Example 1 at -1dpt, -3dpt, and 1dpt. FIG. 8 is a lens cross-sectional view when the optical path of the display optical system of Example 2 is developed. FIGS. 9A, 9B, and 9C are aberration diagrams of the display optical system of Example 2 at -1dpt, -3dpt, and 1dpt.

  The lens cross-sectional view and aberration diagram of the observation optical system of Example 2 are the same as those of Example 1 of FIGS. 4, 5A, 5B, and 5C. FIG. 10 is a lens cross-sectional view when the optical path of the display optical system of Example 3 is developed. FIGS. 11A, 11B, and 11C are aberration diagrams of the display optical system of Example 3 at -1dpt, -3dpt, and 1dpt. The lens cross-sectional view and aberration diagram of the observation optical system of Example 3 are the same as those of Example 1 in FIGS. 4, 5A, 5B, and 5C.

  12 is a lens cross-sectional view when the optical path of the observation optical system of Example 4 is developed. 13A, 13B, and 13C are aberration diagrams of the observation optical system of Example 4 at -1 dpt (diopter), -3 dpt, and 1 dpt. FIG. 14 is a lens cross-sectional view when the optical path of the display optical system of Example 4 is developed. FIGS. 15A, 15B, and 15C are aberration diagrams of the display optical system of Example 4 at -1dpt, -3dpt, and 1dpt.

  The members shown in each number in each lens cross-sectional view correspond to the members shown in each number shown in FIG.

  The aberration diagram shows spherical aberration, astigmatism, and distortion. In the diagrams showing spherical aberration, the solid line d is the d line (wavelength 587.6 nm), and the two-dot chain line F is the F line (wavelength 486.1 nm). Further, a wavelength of 685 nm is shown as visible light used in the display optical system. h is half the pupil diameter of the observer's pupil Ea. In the graph showing astigmatism, a solid line S indicates a value on a sagittal image plane, and a broken line M indicates a value on a meridional image plane. ω represents an apparent field of view (view angle) of the eyepiece 7 when the diopter is −1 diopter (standard diopter).

  The viewfinder optical system of the present invention has an observation optical system and a display optical system. Among these, the display optical system includes, in order from the first display body 8 to the observation side, a first lens 9 having a positive refractive power, and an inner surface reflecting surface that reflects a light beam incident from the light incident surface and emits the light from the light emitting surface. The optical prism 10 and the second lens 11 having a positive refractive power.

When the focal length of the first lens 9 is f ₁ and the focal length of the second lens 11 is f ₂ ,
0.4 <f ₂ / f ₁ <1.8 (1)
The following conditional expression is satisfied.

Condition (1) relates to the ratio of the focal length _{f 2} of the focal length _{f 1} and the second lens 11 of the first lens 9. Conditional expression (1) is for observing display information of the display body 8 with a fine wide viewing angle while preventing the viewfinder optical system from becoming large in the height direction. If the lower limit of conditional expression (1) is not reached, the magnification of the display information of the display body 8 observed by the display optical system is small and the viewing angle is narrowed. On the other hand, if the upper limit of conditional expression (1) is exceeded, the first lens 9 and the optical prism 10 increase, and the viewfinder optical system becomes larger in the height direction. Furthermore, the field curvature and astigmatism of the display optical system increase, making it difficult to observe well.

Further, in each embodiment, the principal point interval in the optical axis direction when the optical path of the first lens 9 and the second lens 11 is developed is H ₁ , and the second lens 11 and the eyepiece lens 7 are positive. The optical path of the lens disposed closest to the image forming member 5 is developed. The main point interval in the optical axis direction and H _2. At this time,
1.0 <f ₂ / (H ₂ −H ₁ ) <11.5 (2)
The following conditional expression is satisfied.

  Conditional expression (2) reduces various aberrations of the display optical system while the diopter of the display information of the display body 8 of the display optical system matches or substantially matches the display information of the focusing screen 3 or the second display body 12. However, this is to increase the viewing angle. If the lower limit of conditional expression (2) is not reached, the magnification of the display information of the display body 8 observed by the display optical system is small and the viewing angle is narrowed. If the upper limit value of conditional expression (2) is exceeded, curvature of field and astigmatism of the display optical system will increase, and good observation will be difficult.

In each embodiment, the numerical ranges of conditional expressions (1) and (2) are more preferably set as follows.
0.45 <f ₂ / f ₁ <1.70 (1a)
3.0 <f ₂ / (H ₂ −H ₁ ) <11.0 (2a)

  In the present embodiment, the second display body 12 is disposed in the vicinity of the focusing screen 3, and the diopter of the subject image formed on the second display body 12 and the diopter of the display information on the first display body 8 are different. Match or approximately match. In the present embodiment, the second display body 12 is not provided, and the diopter of the observation optical system for observing the focusing screen 3 and the diopter of the first display body 8 may be matched.

  Next, numerical data of the observation optical system and the display optical system of each example will be shown. In the numerical data, i represents the i-th optical surface from the display surface of the focusing screen 3 or the display surface of the first display body 8 below.

  In the table showing the numerical data, “ri” represents the paraxial radius of curvature of the i-th optical surface with reference to the focal plane or the display surface of the first display body 8, and “di” represents the i-th surface and the i-th surface. The axial upper surface distance from the (i + 1) th surface is shown. Furthermore, “Ni” represents the refractive index of the i-th glass material with respect to the d-line (wavelength = 578.6 nm), and “νi” represents the Abbe number of the i-th glass material with respect to the d-line.

  In the numerical data of the observation optical system, ri is the focal plane, r2 and r3 are the optical surfaces of the second display body 12, r4 and r5 are the optical surfaces of the condenser lens 4, and r6, r7 and r8 are erecting image forming members (pentadach prisms). 5) corresponds to a light incident surface, a reflecting surface, and a light emitting surface. r9 to r16 correspond to the optical surfaces of the eyepiece optical system 7.

  In the numerical data of the display optical system, r1 and r2 are optical surfaces of the first display body 8, r3 and r4 are optical surfaces of the first lens 9, r5 and r6 are light incident surfaces and light output surfaces of the optical prism 10, and r7. , R8 corresponds to the optical surface of the second lens 11. r9 and r10 correspond to the light incident surface and light output surface of the prism 6, and r11 to r18 correspond to the optical surfaces of the eyepiece optical system 7, respectively.

  In the table, the unit of length described is [mm] unless otherwise specified. However, since the optical system can obtain the same optical performance even when proportionally enlarged or reduced, the unit is not limited to [mm], and other appropriate units can be used. In each numerical data, the surface written as rotationally symmetric aspherical surface in the column of paraxial curvature radius is a rotationally symmetric aspherical shape defined by the following equation (1).

In Equation 1, x is the distance in the optical axis direction from the apex of the lens surface, h is the height in the direction perpendicular to the optical axis, R is the paraxial radius of curvature at the apex of the lens surface, and k is the conic constant. , C ₂ , c ₄ , c ₆ , c ₈ , c ₁₀ are polynomial coefficients. In Table 1 and other tables showing aspherical coefficients, “E-i” represents an exponential expression with a base of 10, that is, “10 ⁻ⁱ ”. Table 1 shows the values of the conditional expressions (1) and (2) described above.

  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.

[Example 1]
<Overview of the optical system>
Image display surface diagonal length L ω
42.48 35.29 °

Numerical data Paraxial radius of curvature Axial distance between top surfaces Refractive index (Nd) Abbe number (νd)
r1 = ∞ d1 = 1.05
r2 = ∞ d2 = 1.22 N2 = 1.52 ν2 = 60.00
r3 = ∞ d3 = 2.51
r4 = -131.94 d4 = 4.25 N4 = 1.80 ν4 = 46.57
r5 = -57.15 d5 = 0.67
r6 = ∞ d6 = 94.71 N6 = 1.66 ν6 = 50.88
r7 = ∞ d7 = 10.08 N7 = 1.66 ν7 = 50.88
r8 = ∞ d8 = 1.10
r9 = -357.23 d9 = 1.30 N9 = 1.85 ν9 = 23.78
r10 = 42.88 d10 = variable
r11 = 43.21 d11 = 4.36 N11 = 1.80 ν11 = 46.58
r12 = -60.45 d12 = variable
r13 = 19.11 d13 = 4.34 N13 = 1.80 ν13 = 46.58
r14 = 136.65 d14 = 0.80
r15 = -1577.55 d15 = 1.00 N15 = 1.70 ν15 = 41.24
r16 = 15.91 d16 = 20.00

Variable interval diopter [Diopter-] -1.00 -3.00 +1.00
d10 3.06 1.51 4.60
d12 3.04 4.59 1.50

<Overall display optics>
Image display surface diagonal length L ₁ ω
7.32 18.29 °

Numerical data Paraxial radius of curvature Axis top spacing Refractive index (Nd) Abbe number (νd)
r1 = ∞ d1 = 0.65 N1 = 1.49 ν1 = 57.40
r2 = ∞ d2 = 1.70
r3 = rotationally symmetric aspheric surface d3 = 2.32 N2 = 1.54 ν2 = 56.00
r4 = rotationally symmetric aspheric surface d4 = 0.70
r5 = ∞ d5 = 18.82 N5 = 1.57 ν5 = 34.00
r6 = ∞ d6 = 0.40
r7 = rotationally symmetric aspheric surface d7 = 3.20 N8 = 1.63 ν8 = 23.90
r8 = rotationally symmetric aspheric surface d8 = 0.30
r9 = ∞ d9 = 29.07 N9 = 1.66 ν9 = 50.88
r10 = ∞ d10 = 1.10
r11 = -357.23 d11 = 1.30 N11 = 1.85 ν11 = 23.78
r12 = 42.88 d12 = variable
r13 = 43.21 d13 = 4.36 N13 = 1.80 ν13 = 46.58
r14 = -60.45 d14 = variable
r15 = 19.11 d15 = 4.34 N15 = 1.80 ν15 = 46.58
r16 = 136.65 d16 = 0.80
r17 = -1577.55 d17 = 1.00 N17 = 1.70 ν17 = 41.24
r18 = 15.91 d18 = 20.00

Aspheric coefficient
r3 R = 44.21 k = -3.63E + 00 c2 = 0.00 c4 = -1.55E-04 c6 = 0.00
c8 = 0.00 c10 = 0.00
r4 R = -15.41 k = 8.61E-02 c2 = 0.00 c4 = 7.05E-06 c6 = 4.63E-06
c8 = -1.60E-07 c10 = 0.00
r7 R = -311.21 k = -5.69E + 02 c2 = 0.00 c4 = 1.45E-05 c6 = -2.09E-07
c8 = 0.00 c10 = 0.00
r8 R = -18.41 k = 1.25E + 00 c2 = 0.00 c4 = 5.40E-05 c6 = -2.25E-07
c8 = 2.37E-09 c10 = -1.67E-12

Variable interval diopter [Diopter-] -1.00 -3.00 +1.00
d12 3.06 1.51 4.60
d14 3.04 4.59 1.50

Conditional Expression Conditional Expression Value (1) f ₂ / f ₁ 1.43
_{(2) f 2 / (H} 2 -H 1) 8.00

[Example 2]
<Overall display optics>
Image display surface diagonal length L ₁ ω
7.32 18.11 °

Numerical data Paraxial radius of curvature Axis top spacing Refractive index (Nd) Abbe number (νd)
r1 = ∞ d1 = 0.65 N1 = 1.49 ν1 = 57.40
r2 = ∞ d2 = 1.70
r3 = rotationally symmetric aspheric surface d3 = 2.32 N2 = 1.63 ν2 = 23.90
r4 = rotationally symmetric aspheric surface d4 = 0.70
r5 = ∞ d5 = 18.82 N5 = 1.49 ν5 = 57.40
r6 = ∞ d6 = 0.40
r7 = rotationally symmetric aspheric surface d7 = 3.20 N8 = 1.63 ν8 = 23.90
r8 = rotationally symmetric aspheric surface d8 = 0.30
r9 = ∞ d9 = 29.07 N9 = 1.66 ν9 = 50.88
r10 = ∞ d10 = 1.10
r11 = -357.23 d11 = 1.30 N11 = 1.85 ν11 = 23.78
r12 = 42.88 d12 = variable
r13 = 43.21 d13 = 4.36 N13 = 1.80 ν13 = 46.58
r14 = -60.45 d14 = variable
r15 = 19.11 d15 = 4.34 N15 = 1.80 ν15 = 46.58
r16 = 136.65 d16 = 0.80
r17 = -1577.55 d17 = 1.00 N17 = 1.70 ν17 = 41.24
r18 = 15.91 d18 = 20.00

Aspheric coefficient
r3 R = -81.57 k = -1.86E + 01 c2 = 0.00 c4 = 1.10E-04
c6 = 0.00 c8 = 0.00 c10 = 0.00
r4 R = -11.43 k = -7.11E-01 c2 = 0.00 c4 = 1.58E-05
c6 = 5.31E-06 c8 = -1.39E-07 c10 = 0.00
r7 R = -134.17 k = -2.06E + 02 c2 = 0.00 c4 = 1.56E-05
c6 = -4.98E-08 c8 = 0.00 c10 = 0.00
r8 R = -18.28 k = 1.19E + 00 c2 = 0.00 c4 = 5.50E-05
c6 = -1.01E-07 c8 = 2.35E-09 c10 = 2.20E-12

Variable interval diopter [Diopter-] -1.00 -3.00 +1.00
d12 3.06 1.51 4.60
d14 3.04 4.59 1.50

Conditional expression Conditional expression Value (1) f ₂ / f ₁ 1.61
_{(2) f 2 / (H} 2 -H 1) 9.49

[Example 3]
<Overall display optics>
Image display surface diagonal length L ₁ ω
7.32 18.84 °

Numerical data Paraxial radius of curvature Axis top spacing Refractive index (Nd) Abbe number (νd)
r1 = ∞ d1 = 0.65 N1 = 1.49 ν1 = 57.40
r2 = ∞ d2 = 1.70
r3 = rotationally symmetric aspheric surface d3 = 2.32 N2 = 1.63 ν2 = 23.90
r4 = rotationally symmetric aspheric surface d4 = 0.70
r5 = ∞ d5 = 18.82 N5 = 1.80 ν5 = 46.58
r6 = ∞ d6 = 0.40
r7 = rotationally symmetric aspheric surface d7 = 3.40 N8 = 1.77 ν8 = 49.24
r8 = rotationally symmetric aspheric surface d8 = 0.30
r9 = ∞ d9 = 29.07 N9 = 1.66 ν9 = 50.88
r10 = ∞ d10 = 1.10
r11 = -357.23 d11 = 1.30 N11 = 1.85 ν11 = 23.78
r12 = 42.88 d12 = variable
r13 = 43.21 d13 = 4.36 N13 = 1.80 ν13 = 46.58
r14 = -60.45 d14 = variable
r15 = 19.11 d15 = 4.34 N15 = 1.80 ν15 = 46.58
r16 = 136.65 d16 = 0.80
r17 = -1577.55 d17 = 1.00 N17 = 1.70 ν17 = 41.24
r18 = 15.91 d18 = 20.00

Aspheric coefficient
r3 R = -73.59 k = -1.21E + 00 c2 = 0.00 c4 = 1.16E-04
c6 = 0.00 c8 = 0.00 c10 = 0.00
r4 R = -22.79 k = -2.22E + 00 c2 = 0.00 c4 = 1.72E-04
c6 = 7.83E-06 c8 = -2.17E-07 c10 = 0.00
r7 R = -104.85 k = -4.34E + 01 c2 = 0.00 c4 = 3.72E-05
c6 = -1.22E-07 c8 = 0.00 c10 = 0.00
r8 R = -17.42 k = 8.63E-01 c2 = 0.00 c4 = 5.26E-05
c6 = -2.95E-08 c8 = 1.74E-09 c10 = 6.63E-13

Variable interval diopter [Diopter-] -1.00 -3.00 +1.00
d12 3.06 1.51 4.60
d14 3.04 4.59 1.50

Conditional Expression Conditional Expression Value (1) f ₂ / f ₁ 0.52
(2) f ₂ / (H ₂ −H ₁ ) 4.48

[Example 4]
<Overview of the optical system>
Image display surface diagonal length L ω
26.63 30.00 °

Numerical data Paraxial radius of curvature Axis top spacing Refractive index (Nd) Abbe number (νd)
r1 = ∞ d1 = 1.05
r2 = ∞ d2 = 1.22 N2 = 1.52 ν2 = 60.00
r3 = ∞ d3 = 1.53
r4 = -131.00 d4 = 2.50 N4 = 1.80 ν4 = 46.57
r5 = -57.00 d5 = 0.67
r6 = ∞ d6 = 81.85 N6 = 1.66 ν6 = 50.88
r7 = ∞ d7 = 10.00 N7 = 1.66 ν7 = 50.88
r8 = ∞ d8 = 0.50
r9 = 131.11 d9 = 1.00 N9 = 1.85 ν9 = 23.78
r10 = 41.98 d10 = variable
r11 = 39.36 d11 = 4.58 N11 = 1.80 ν11 = 46.58
r12 = -60.01 d12 = variable
r13 = 17.19 d13 = 4.29 N13 = 1.80 ν13 = 46.58
r14 = 55.89 d14 = 1.14
r15 = 169.37 d15 = 1.86 N15 = 1.83 ν15 = 37.16
r16 = 14.49 d16 = 24.00

Variable interval diopter [Diopter-] -1.00 -3.00 +1.00
d10 2.23 0.50 4.00
d12 2.22 3.95 0.45

<Overall display optics>
Image display surface diagonal length L ₁ ω
7.32 18.29 °

Numerical data Paraxial radius of curvature Axis top spacing Refractive index (Nd) Abbe number (νd)
r1 = ∞ d1 = 0.65 N1 = 1.49 ν1 = 57.40
r2 = ∞ d2 = 1.70
r3 = rotationally symmetric aspheric surface d3 = 2.32 N2 = 1.54 ν2 = 56.00
r4 = rotationally symmetric aspheric surface d4 = 0.70
r5 = ∞ d5 = 18.00 N5 = 1.53 ν5 = 56.00
r6 = ∞ d6 = 0.40
r7 = rotationally symmetric aspheric surface d7 = 3.20 N8 = 1.63 ν8 = 23.90
r8 = rotationally symmetric aspheric surface d8 = 0.30
r9 = ∞ d9 = 28.00 N9 = 1.66 ν9 = 50.88
r10 = ∞ d10 = 0.50
r11 = 131.11 d11 = 1.00 N11 = 1.85 ν11 = 23.78
r12 = 41.98 d12 = variable
r13 = 39.36 d13 = 4.58 N13 = 1.80 ν13 = 46.58
r14 = -60.01 d14 = variable
r15 = 17.19 d15 = 4.29 N15 = 1.80 ν15 = 46.58
r16 = 55.89 d16 = 1.14
r17 = 169.37 d17 = 1.86 N17 = 1.83 ν17 = 37.16
r18 = 14.49 d18 = 24.00

Aspheric coefficient
r3 R = -207.46 k = -1.70E + 02 c2 = 0.00 c4 = 4.79E-05
c6 = 0.00 c8 = 0.00 c10 = 0.00
r4 R = -17.00 k = -9.40E + 00 c2 = 0.00 c4 = 3.13E-05
c6 = 6.58E-07 c8 = -1.38E-07 c10 = 0.00
r7 R = -146.95 k = -4.44E + 02 c2 = 0.00 c4 = 3.51E-05
c6 = -2.05E-07 c8 = 0.00 c10 = 0.00
r8 R = -18.93 k = 9.51E-01 c2 = 0.00 c4 = 5.53E-05
c6 = -1.28E-07 c8 = 1.98E-09 c10 = -8.08E-12

Variable interval diopter [Diopter-] -1.00 -3.00 +1.00
d10 2.23 0.50 4.00
d12 2.22 3.95 0.45

Conditional Expression Conditional Expression Value (1) f ₂ / f ₁ 0.99
(2) f ₂ / (H ₂ −H ₁ ) 10.56

DESCRIPTION OF SYMBOLS 1 Shooting lens 2 Movable mirror 3 Focus plate 4 Condenser lens 5 Erect image forming member 6 Prism 6a Optical surface 6b Optical surface 6c Optical surface 7 Eyepiece optical system 8 First display body 9 First lens 10 Optical prism 11 Second lens 12 Second display body 13 Distance frame display 14 Information display Fa Optical axis Fb of observation optical system Optical axis of display optical system IP imaging means

Claims (8)

An observation optical system that guides a luminous flux based on a subject image formed on a predetermined surface through an erect image forming member and two optical surfaces inclined with respect to the optical axis to an eyepiece; A display optical system that reflects the light beam from the first display body provided in the vicinity of the standing image forming member by the two optical surfaces and guides the light beam to the eyepiece, and the observation optical system and the display optical system In the finder optical system for observing the subject image and the display information displayed on the first display body in the same field of view,
The display optical system includes, in order from the first display body to the observation side, a first lens having a positive refractive power, and an optical prism having an inner reflection surface that reflects a light beam incident from a light incident surface and emits the light from the light emission surface. And a second lens having a positive refractive power. When the focal length of the first lens is f ₁ and the focal length of the second lens is f ₂ ,
0.4 <f ₂ / f ₁ <1.8
The finder optical system according to claim 1, wherein the following conditional expression is satisfied. The focal length of the second lens is f ₂ , the distance between principal points of the first lens and the second lens in the optical axis direction is H ₁ , and the positive lens among the lenses constituting the second lens and the eyepiece is used. when the main point interval in the optical axis direction of the closest to the lens disposed figurine forming member and H _2,
1.0 <f ₂ / (H ₂ −H ₁ ) <11.5
The finder optical system according to claim 1, wherein the following conditional expression is satisfied.   A second display body is disposed in the vicinity of the predetermined surface, and a diopter of display information displayed on the second display body and a diopter of display information displayed on the first display body of the display optical system. The viewfinder optical system according to any one of claims 1 to 3, wherein the two match each other.   5. The diopter of the subject image formed on the predetermined surface and the diopter of the display information of the first display body of the display optical system coincide with each other. The finder optical system described in 1.   6. The finder optical system according to claim 1, wherein at least one lens surface of the two optical surfaces includes a half mirror or a dichroic mirror.   The two optical surfaces are each formed of a single transparent member, and a light beam from a subject image formed on the predetermined surface is a first optical surface or a second optical surface of the two optical surfaces. The light beams from the first display body are reflected in the order of the second optical surface and the first optical surface, and then pass through the second optical surface. The finder optical system according to claim 1, wherein the finder optical system passes through and enters the eyepiece.   The finder optical system according to any one of claims 1 to 7, an imaging optical system that forms a subject image on a predetermined surface of the finder optical system, and imaging that receives an image formed by the imaging optical system And an imaging device.