JP3236734B2 - Diopter correction device for back-drive AF single-lens reflex camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing (hereinafter, referred to as AF) for driving a body core for holding a film at an in-focus position on the basis of a shift amount of a subject from a focal plane to be formed.
Regarding diopter correction of the viewfinder of a single-lens reflex camera,
In the finder that operates integrally with the body core during focusing, the diopter can be corrected by an external operation member at any position regardless of the position of the body core after focusing, and a load is applied to the focusing drive. No diopter correction device.

[0002]

2. Description of the Related Art The present applicant has already proposed a new focus driving method for a camera in Japanese Patent Application Laid-Open No. 5-173225. An AF focusing drive mechanism is provided on the camera body side.
In the F-focus drive, the film feeding and holding mechanism and the film plane receiving portion including the single-lens reflex finder optical system are integrally driven and controlled to the focal plane of the subject to be imaged. That is, with respect to a camera system that performs focusing by changing the distance of the film surface with respect to the photographing lens by moving the camera body, a film feeding and holding mechanism to be a core in the camera while leaving the taking-out lens feeding mechanism as it is, This is a system in which a mirror box and the like are integrally driven for focusing.

More specifically, the camera body is mounted so as not to impair the good image performance of the conventional non-AF photographing lens and to prevent a load on the focusing drive by the motor on the camera body side. It is divided into a core portion and an outer case portion including the core portion, and a fixed portion including the outer case is provided with a mount for mounting a photographing lens and other external operation members while serving for camera holding. Further, the body core and the outer case are connected by a sophisticated slider device, and a body core including a film feed holding element and a mirror box in the case of a single-lens reflex camera inside the outer case is moved in the optical axis direction of the taking lens. It is intended to enable quick drive control by a motor.

The body core constituting the movable portion includes at least a winding / rewinding mechanism, a guide roller, a film feeding / holding device including an inner lid having a pressure plate, a focal plane shutter, a finder, a distance measuring / photometric element, and an optical system thereof. A mirror box having a film sensitivity setting probe and a locking device for the inner lid, a slider device and a mounting device for mounting the photographing lens at least in the outer case, the slider device being driven in parallel in the optical axis direction of the body core and the photographing lens. And enables the body core to be driven in the optical axis direction. The fixing part including the outer case is provided with a mount for mounting a photographing lens, an input / output device of the photographing lens and a battery chamber, for loading and unloading a film, and for protecting the drive of the body core from an external force applied to the outer case. It has a rear lid and its locking device, a release button and other operation buttons, a dial, a display section, an accessory mounting seat, and the like. In the photographing drive of the camera configured as described above, photometry and distance measurement are calculated by the release of the photographing operation, and the focusing drive based on this is moved in the optical axis direction unlike the conventional photographing lens drive. After focusing, after the exposure is completed by a series of sequence operations of the mirror, the aperture of the lens, and the shutter, the film is wound up and one shooting operation ends. The above-described focusing drive of the body core has the same result as the case where the entire photographic lens is extended, and the initial purpose of utilizing the goodness of the system of the non-AF lens group can be achieved. However, in the case of a single-lens reflex camera, the finder optical system moves in the optical axis direction by focusing, and furthermore, since the outer case is fixed, when the body core moves to the infinity side, the eyepiece becomes deep and it is difficult to see. Not only that, if an external correction lens is attached to the fixed-side viewing port for diopter correction, the above-described focusing drive causes a change in position between the eyepiece and the correction lens, and the diopter changes, making it difficult to see. Or the inconvenience that some people cannot see it.

[0005]

In the case of a single-lens reflex camera, a finder image is interrupted by a quick return of a mirror every time an image is taken. In addition, in AF mode, functions such as moving subject prediction and continuous shooting are added, so there is no time to reset the lens to be driven for focusing to the reference position each time one frame is shot, and distance measurement is performed from that position. It is driving in focus.

[0006] In the case of a back-drive AF single-lens reflex camera, this point is exactly the same, and the next photographing operation is started from the position of the body core that has been driven to focus, and the distance is measured and the focus is driven. A diopter correction device is built in the viewfinder of the back-drive AF single-lens reflex camera, and the diopter correction can be easily performed by an external operation regardless of the position of the body core, and the diopter correction device drives the focus of the body core. So as not to overload.

[0007]

According to the present invention, there is provided a finder optical system having at least a film feeding / holding device, a shutter, a mirror, a distance measuring element, a focus glass, a pentaprism, and an eyepiece. Back-driven autofocus comprising: a body core comprising: a slider device for driving the body core in the optical axis direction; and an outer case incorporating the body core and the slider device and having at least a mount for mounting a photographing lens and a release button. In a single-lens reflex camera, a device for correcting the diopter by moving the eyepiece in the optical axis direction of the finder by operating a diopter correction operating member provided on a fixed side such as the outer case, for diopter correction An input member of an eyepiece moving mechanism for moving the eyepiece in the optical axis direction, A spur gear that is rotated by operating the visibility correction operation member is provided on the camera fixed side in parallel with the optical axis direction with a length slightly equal to or slightly longer than the focusing drive movement amount of the body core, and meshes the input member and the spur gear. Then, the diopter correction is performed by rotating the spur gear, and the input member is configured to be slid while engaged with the spur gear at the time of focusing driving, and the eyepiece is corrected for diopter when driving the body core during focusing. The diopter can be moved without changing the relative position of the finder with respect to the focus plane, and the eyepiece can be moved in accordance with the operation of the diopter correction operation member to correct the diopter regardless of the position of the body core. Provided is a diopter correction apparatus for a back-drive AF single-lens reflex camera.

A back-drive type autofocus single-lens reflex camera, wherein the eyepiece is moved in the optical axis direction of the finder to correct the diopter by operating a diopter correcting operation member provided on a fixed side such as an outer case. In the apparatus, the eyepiece includes at least two groups of lenses that are fixed and movable, and a movable eyepiece frame that holds the movable eyepiece is provided so as to be able to move straight in the optical axis direction with respect to an eyepiece fixed frame that holds the fixed eyepiece, and the eyepiece is fixed. A rack plate having a lead hole and a rack is slidably provided on a plane around the frame, and the cam follower pins of the movable eyepiece frame are fitted into the lead holes of the rack plate,
The spur gear extending parallel to the optical axis direction is meshed with a rack of the rack plate, and the spur gear is directly or indirectly coupled to an external operation member.

[0009]

[0010]

That is, in the back-drive AF single-lens reflex camera, the fixed outer case includes the body core, and the position of the eyepiece is relatively changed with respect to the focus surface of the finder optical system of the body core. This is the basis of the diopter correction of the present invention. Further, the optical axis of the eyepiece is set in parallel with the focus driving direction of the body core (the optical axis direction of the photographing lens), and a spur gear is rotatable on the fixed side (the outer case) in parallel with the optical axis direction. Support. Further, the spur gear is rotated by an operation of an external diopter correction operation member, and is extended in the optical axis direction by at least the focusing drive stroke of the body core plus a slight margin. Further, the spur gear meshes with a rack of an eyepiece moving device provided around the movable eyepiece, and the rack slides while meshing with the spur gear when the body core is driven for focusing, It is an object of the present invention to provide a back-drive AF single-lens reflex camera, wherein the correction device does not become a load at the time of in-focus driving, and enables diopter correction regardless of the position of the body core.

[0012]

The eyepiece located behind the pentaprism is constituted by two or two groups of concave and convex, the concave lens on the pentaprism side is fixed to the focal plane, and the convex lens is driven in the optical axis direction behind the concave lens. Diopter correction. Then, so that the eyepiece moving device of the diopter correction device does not hinder the optical axis direction driving (focusing driving) of the body core,
And a mechanism for directly or indirectly changing the rotation axis angle, such as a bevel gear or a helical gear, by operating an external diopter correction operation member so that diopter correction can be performed regardless of the position of the body core. Rotating the spur gear extending in the optical axis direction, meshing the spur gear with a rack plate rack of the eyepiece moving device provided on a plane around the eyepiece, and rotating the spur gear by rotating the spur gear. The movable eyepiece (the convex lens) is caused to slide straight in the optical axis direction by sliding on the surface around the finder optical axis.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a longitudinal section at an optical axis position when a body core is at a super-infinity position in a back-drive AF single-lens reflex camera provided with a diopter correction device of the present invention, and a side view of the diopter correction device. It is. FIG. 2 shows the fixed eyepiece frame side surface with the external operation member and the spur gear removed from FIG. 1, and is a state diagram in which the movable eyepiece is closest to the fixed eyepiece. FIG. 3 is a composite view taken along the arrows AA and C of FIG. 1 and is a rear view in which the eyepiece shutter mechanism of FIG. 7 is removed, and FIG.
FIG. 3 is a view taken in the direction of arrows BB in FIG. 1, showing a state in which the body core is at a very infinite position as in FIG. 1 and the movable eyepiece is closest to the fixed eyepiece as in FIG. FIG. 5 is a vertical sectional view of the finder at an ultra-infinity position along the optical axis, showing a state in which the movable eyepiece comes to a position farthest from the fixed eyepiece. FIG. 6 is a state diagram when the finder portion of FIG. 5 is moved to the close end as it is, and FIG. 7 is a rear view of an eyepiece shutter mechanism provided inside the finder viewing port of the single-lens reflex camera. FIG. 8 is a "closed" state diagram of the eyepiece shutter.

The main structure of the finder of the back-drive AF single-lens reflex camera of the present invention will be described with reference to FIG. First, the body core and the outer case will be described. In FIG. 1, a lens mount 2 is screwed to a mount base 1 which is a main part on the fixed side of the camera.
A decorative cover 3 is fixed around the lens mount 2. Although not shown, a body 16, a mirror box 20 including a finder and a mirror quick return mechanism, and a body core composed of a winding and rewinding mechanism are mounted on the mount base 1 via a slider device in the optical axis direction of the photographing lens. It is provided so that it can go straight. FIG.
The rear frame 6, which is partially illustrated on the right side of the figure, is screwed to the mount base 1 so as to include the body core, form an outer shell of the camera with a rigid frame, and assemble the upper cover 4 and operation members. To complete a back-drive AF single-lens reflex camera.

Next, a diopter correcting apparatus according to the present invention will be described. First, the configuration of the finder of the body core will be described. Half mirror 18, Total reflection mirror 19
Although not shown, an assembly in which the finder housing 27 is screwed to the upper part of the mirror box 20 having the distance measuring module at the bottom is prepared. Next, an assembly of the finder optical system is made. A focus glass frame 23 is provided at the lowermost portion of the rear of the pentaprism receiver 21 so that the focus glass 22 can be replaced.
Is fixed to the shaft and spring-fixed at the front. The leaf spring 23
a, the focus glass 22 is received by the pentaprism receiver 2;
1 is pressed into contact with the lowermost portion to secure the focus position. A focus glass 22, a condenser lens 24, a condenser lens holder 25,
The finder display section and the pentaprism 26 are placed at predetermined positions and integrated with a prism holding spring.

Next, the pentaprism receiver assembly is integrated with the mirror box assembly. The pentaprism receiver assembly is placed above the mirror box assembly, and focus adjustment is performed between the flange surface of the finder housing 27 and the pentaprism receiver 21 using a reference lens via a washer or the like. After that, screw it down. The mirror box assembly incorporating the above-described pentaprism receiving assembly is mounted on the body 16 to which the focal plane shutter 17 and the like are screwed at the upper part of the finder housing 2.
7 and the mirror box 2 at the bottom
0 is directly screwed to the body 16.

Next, among the diopter correcting devices for the finder, a device for moving the eyepiece on the body core side will be described. In FIG. 4, two groups of concave and convex eyepieces are a movable eyepiece frame 3 in which a movable eyepiece (convex lens) 34 is bonded to a key groove 31 a and a guide projection 31 b on the left and right sides of a fixed eyepiece frame 31 to which a fixed eyepiece (concave lens) 32 is bonded.
3 and the guide groove 33b.
Then, the holding plate 35 is screwed to the rectilinear key 33a in the concave portion on the side of the rectilinear key groove. With this, the optical axes of the two eyepieces can be set, and the movable eyepiece 34 can smoothly move straight in the optical axis direction. Cam follower pin 33 of the rectilinear key portion integrally formed with the movable eyepiece frame 33
The rack groove 36a of the rack plate 36 is fitted into the groove c, and the rack plate 36 is slidably attached to the side surface of the fixed eyepiece frame 31 by the rack pressing plate 37. As a result, a part of the rack 36b of the rack plate protrudes outward from the notch of the rack holding plate 37. As shown in FIG. 5, the pentaprism 2 is provided above the fixed eyepiece frame 31.
A light measuring condenser lens 28, a mirror 29, a light measuring element 30, and a circuit therefor are arranged at a position corresponding to the exit surface on the upper part of the light source 6. The alternate long and short dash line indicates the position where the movable eyepiece comes closest to the fixed eyepiece.

The eyepiece assembly having the above-described structure includes projections 21a on the left and right of the rear portion of the pentaprism receiver 21.
Then, the fixed eyepiece frame 31 is screwed at the ear 31c (see FIG. 4). The order of assembling is not limited to this, and the pentaprism assembly and the eyepiece assembly are integrated and then attached to the mirror box assembly.
May be screwed on.

Next, a description will be given of the configuration of the viewing port base 7, which is a device for moving the eyepiece on the outer case side, in the diopter correcting device for the finder. 1 and 7, a dustproof glass 8, an eyepiece frame 9, a mask 10 and an eyepiece receiving holding frame 11 are provided at the center of the viewing port base 7. Inside, eyepiece shutter blades 12 and 13 are fixed by shafts 12a and 13a, and one of them 12a protrudes to the outside, and the operation lever 14 is screwed so as to be rotatable integrally with the shutter blade 12. The groove 13a of the blade and the pin at the tip of the other blade 12 are engaged, and the two eyepiece shutter blades are turned by the rotation of the operation lever 14 so that the field mask 10 of the viewing port is opened.
(See FIGS. 7 and 8). As described above, the functions such as the photometry and the eyepiece shutter around the viewing opening of the single-lens reflex camera are not hindered at all.

In FIG. 4, a spur gear 41 having a bevel gear portion 41a at the tip of a spur gear portion slightly longer than the focus drive amount of the body core (L in FIG. 1) is rotatably supported by a support plate 42. At the same time, the click leaf spring 43 is screwed so that the steel ball faces the spur gear portion, thereby producing an assembly of the spur gear support plate having a click feeling. Next, bevel gear support plate 4
The bevel gear support plate 44 is inserted into the front end of the spur gear 4, and the bevel gear support plate 44 is viewed together with the spur gear support plate assembly while the bevel gear 45 is meshed with the bevel gear 41a integrally formed in front of the spur gear. The mouth base 7 is screwed inside the left end in FIG. Further, the spur gear support 42 and the bevel gear support 44 may be configured as one component.

Next, returning to the beginning of this section, the incorporation of the viewing port base assembly into the assembly up to the rear frame 6 will be described. After assembling the body core integrating the mirror box, the finder assembly, and the like to the mount base 1 via a slider device, and then assembling the rear frame 6 and the like, the assembly of the viewing base having the above-described configuration is changed to the viewing base. Left and right ears 7
a, 7b, a projection 6 of the rear frame corresponding to a fixing portion of the camera
a, screw to 6b. As a result, the rack 36b of the rack plate meshes with the spur gear 41, the spur gear 41 extends in parallel with the optical axis, and the external operation member mounting portion of the bevel gear 45 is connected to the pentagonal portion of the upper cover 4. Located on the inside of the slope.

The viewing base assembly is fixed, and the finder including the eyepiece is movable together with the camera body during focusing driving. However, since the spur gear 41 extends parallel to the optical axis, the spur gear 41 and the rack 36b slide while being engaged. Therefore, almost no load is applied to the focusing drive torque of the body core.

After the strobe circuit connector 15 is attached to a position corresponding to the mounting seat of the finder portion having the above-described configuration, the upper cover 4 to which the mounting seat 5 and the like are fixed is screwed to the mount base 1 and the rear frame 6. Further, the diopter correction dial 46
Is screwed to the bevel gear 45 through the upper cover 4 (FIG. 3).
reference).

Next, the operation of the diopter correcting device for changing the relative position of the eyepiece of the finder of the back-driven AF single-lens reflex camera assembled as described above will be described. When the diopter correction dial 46 is turned, the bevel gears 45, 41a
, The spur gear 41 rotates. At this time, since the steel ball urged by the click leaf spring 43 is in contact with the teeth of the spur gear 41, a click feeling is transmitted to the diopter correction dial 46. The rack plate 36 meshing with the rotation of the spur gear 41 slides on the side of the fixed eyepiece frame 31 and moves the movable eyepiece frame 33 in the optical axis direction via the cam follower pin 33c engaged with the lead groove 36a. .
When the diopter correction dial 46 is turned while viewing the viewfinder image, the movable eyepiece (concave lens) 34 is moved in the optical axis direction and stopped when the best image is obtained. The position of the eyepiece is a position suitable for the diopter of the person. That is, in this embodiment, when the movable eyepiece approaches the fixed eyepiece as shown in FIG. 4, the diopter becomes negative, and as shown by the solid line in FIG. 5, the diopter decreases when the movable eyepiece moves away from the fixed eyepiece. Become a plus. If the user remembers the indices of the dial 46 and the upper cover 4, the diopter can be adjusted from the next time without looking through the finder. The operation restriction of the diopter correction is performed by bringing the movable eyepiece frame 33 into contact with the fixed eyepiece frame 31 and the rack retainer 37 or by limiting the rotation of the dial 46.

Further, the correction dial 46 may be directly connected to the spur gear. This direct connection does not require meshing of the bevel gears, thus providing a very simple mechanism. On the other hand, it is difficult to adjust the diopter while looking through the viewfinder.

Although the above-described eyepiece has been described as an example in which the eyepiece is divided into two concave and convex lenses, the diopter can be corrected by moving the two eyepieces in a group along the optical axis.
However, the movement amount of the eyepiece is larger than that of the two-piece eyepiece.

The gist of the present invention can be utilized even if the linear movement mechanism of the eyepiece by the combination of the linear keyway and the linear key is changed to the combination of the shaft and the guide hole.

Although the diopter correction device is unnecessary for a person with normal visual acuity, the viewfinder image is blurred no matter how much the camera focuses on an AF single-lens reflex camera for an unspecified number of people. I can't take good photos. The diopter correction device is indispensable for a single-lens reflex camera, and it is one of the essential specifications for a back focus AF single-lens reflex camera, since it is meaningless to attach an external diopter correction lens.

[0029]

According to the present invention, when an external correction lens is attached to the fixed part of the viewing opening for diopter correction in the back-drive AF single-lens reflex camera, the eyepiece and the external correction lens are driven by the above-described body core focusing drive. , And the inconvenience occurs that the diopter changes each time the focusing drive is performed or in accordance with the amount of drive. The built-in diopter correction device of the present invention eliminates the need for an external diopter correction lens and can solve the above problem.

In the case of a back-drive AF single-lens reflex camera, the finder optical system must be movable in the optical axis direction by focusing, and the upper cover is fixed. However, if the finder optical system is designed in advance at the high eye point, and the upper corner of the finder field of view due to the exit surface of the pentaprism is missing, and the diopter correction device according to the present invention is added, the focusing of the body core can be achieved. Even if the position of the finder changes due to driving, a change in diopter can be prevented, so that the finder always looks good.

Further, when the diopter is adjusted, the diopter correction device of the present invention can correct the diopter at any position regardless of the position of the body core. Since the diopter does not need to be corrected after resetting to the position, the operability is excellent.

The diopter correction device according to the present invention, in which the diopter can be adjusted by an external operation, does not apply any load to the in-focus driving, so that the in-focus driving time and battery consumption are not a negative factor. In the case of a single-lens reflex camera, the viewfinder image is interrupted by the quick return of the mirror each time shooting is performed. In addition, AF single-lens reflex cameras have additional functions such as moving object prediction and continuous shooting of the subject, so there is no time to reset the body core to be driven to focus to the reference position each time one frame is shot, and focus drive The next shooting operation must be started from the position of the body core that has been set, and the distance must be measured and the focus must be driven. The diopter correction device of the present invention has sufficiently achieved the basic specifications of the AF single-lens reflex camera.

Compared to the diopter correction device of the conventional single-lens reflex camera, the configuration is not particularly complicated, so that other functions such as the photometry and the eyepiece shutter around the viewfinder viewing port are not hindered and the cost is reduced. It is of high practical value as it can be realized with.

[Brief description of the drawings]

FIG. 1 is a side view of a diopter correction mechanism in a longitudinal section at an optical axis position of a finder at a super-infinity position in a back-drive AF single-lens reflex camera of the present invention.

FIG. 2 is a view showing a side surface of a fixed eyepiece frame in which an external operation member and a spur gear are removed from the diopter correction mechanism of FIG. 1 and showing a state when a movable eyepiece comes closest to the fixed eyepiece.

3 is a composite view of the view taken in the direction of arrows AA and C in FIG. 1 and is a rear view of the viewfinder from which the eyepiece shutter mechanism of FIG. 7 is removed.

FIG. 4 is a horizontal sectional view of the pentaprism and the eyepiece in a view taken in the direction of arrow BB in FIG. 3, which is simplified except for an eyepiece shutter.

FIG. 5 is a longitudinal sectional view at an optical axis position when a finder section is at a position at ultra-infinity.

FIG. 6 is a state diagram when the finder section of FIG. 5 has moved to a closest end position.

FIG. 7 is a rear view of the eyepiece shutter mechanism provided inside the viewfinder opening of the single-lens reflex camera, and is a state diagram when the eyepiece shutter is “open”;

FIG. 8 is a state diagram when the eyepiece shutter is “closed” with respect to FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mount base 2 Lens mount 4 Upper cover 5 Accessories mounting seat 6 Rear frame 7 View base 8 Dustproof glass 10 Field mask 12 Eyepiece shutter blade 13 Eyepiece shutter blade 16 Body 17 Focal plane shutter 18 Half mirror 19 Total reflection for distance measurement Mirror 20 Mirror Box 21 Penta Prism Receiver 22 Focus Glass (Fresnel Lens) 23 Focus Glass Frame 24 Condenser Lens 25 Condenser Lens Holder 26 Penta Prism 27 Viewfinder Housing 31 Fixed Eyepiece Frame 32 Fixed Eyepiece (Concave Lens) 33 Movable Eyepiece Frame 34 Movable Eyepiece (Convex lens) 35 Holding plate 36 Rack plate 37 Rack holding plate 41 Spur gear 42 Spur gear support plate 43 Click spring plate 44 Bevel gear support plate 45 Bevel gear 46 Degree correction dial

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03B 13/00-13/28 G02B ^7/ 28-7/40 G03B 13/36

Claims (2)

(57) [Claims] 1. A body core comprising at least a film feeding and holding device, a shutter, a mirror, a distance measuring element, a finder optical system having a focus glass, a pentaprism, and an eyepiece, and a slider device for driving the body core in an optical axis direction. And a back-drive type autofocus single-lens reflex camera including the body core and the slider device, and an outer case including at least a photographing lens mounting mount and a release button, provided on a fixed side such as the outer case. In the device for correcting the diopter by moving the eyepiece in the optical axis direction of the finder by operating the diopter correction operating member, the eyepiece is moved in the optical axis direction for diopter correction.
Input member of the eyepiece moving mechanism, and the diopter correction operation
Focus the body core on a spur gear that rotates by manipulating members
Make the camera the same or slightly longer than the drive
The input member and the spur gear are meshed with each other.
The diopter is corrected by rotating the spur gears.
The force member is configured to slide while being engaged with the spur gear, and upon driving the body core during focusing, the eyepiece is movable without changing the relative position of the diopter-corrected finder with respect to the focusing surface, and ,
A diopter correction device for a back-drive AF single-lens reflex camera, wherein the diopter can be corrected by moving the eyepiece in accordance with the operation of the diopter correction operation member regardless of the position of the body core. . 2. A back-drive type auto-focus single-lens reflex camera, wherein the eyepiece is moved in the optical axis direction of a finder by operation of a diopter correction operation member provided on a fixed side such as an outer case to correct diopter. In the apparatus, the eyepiece includes at least two groups of lenses that are fixed and movable, and a movable eyepiece frame that holds a movable eyepiece is provided to be movable in a direction of an optical axis with respect to an eyepiece fixed frame that holds a fixed eyepiece, and the eyepiece is fixed. A rack plate having a lead hole and a rack is slidably provided on a plane around the frame, and a cam follower pin of the movable eyepiece frame is fitted into the lead hole of the rack plate, and extends parallel to the optical axis direction. The spur gear is engaged with the rack of the rack plate, and the spur gear is directly or indirectly connected to an external operating member. A diopter correction apparatus for a back-drive AF single-lens reflex camera, wherein the diopter correction apparatus is combined with a diopter.