JPH0651388A - Display device in finder for automatic focusing single-lens reflex camera - Google Patents

Abstract

PURPOSE:To display whether the deviation quantity of a focal length for responding to AF falls within the adjustable range of a distance between the front block and the back block of a camera main body or not, that means, within the responding range of the AF with respect to the present position of the distance ring of a mounted lens or not as for a back focus control system automatic focusing single-lens reflex camera. CONSTITUTION:An AFCPU 20 is actuated so as to move the back block B to a focusing position with respect to the front block A of the camera main body by controlling a BF driving circuit 21 based on range-finding data and driving a driving motor 7a. By the AFCPU 20, the focusing position with respect to the present position of the distance ring of the lens is calculated based on the range-finding data before a focusing action is executed. The focusing position is displayed on a display part 24 through a display driving circuit 22. When it is within the response feasible range of the AF, the display is executed on a corresponding display frame by lighting. When it is out of the response feasible range of the AF, the display is executed at a corresponding warning part by flickering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back focus control system A for performing AF by adjusting a flange back.
The present invention relates to an F single-lens reflex camera, and more specifically, to an in-viewfinder display device that displays whether or not the focus shift amount for focusing is within the back focus adjustment range at the current distance ring position of the lens in the camera.

[0002]

2. Description of the Related Art A conventional AF single-lens reflex camera adopts a method of focusing a subject by adjusting a distance ring of a photographing lens. Further, a motor in which a motor as a drive source is arranged in the body and a motor in which the motor is built in the lens have been put into practical use. The AF single-lens reflex camera generally has a structure in which another autofocus lens can be attached by using a manual focus lens or an adapter, but it is naturally necessary to manually adjust the focus. Therefore, the inventor of the present invention has proposed an autofocus single-lens reflex camera in which the camera body is divided into a front block and a rear block and focusing is performed by adjusting the flange back of the lens (Patent application 3
-342838). According to this proposal, all interchangeable lenses can be used as an autofocus lens regardless of whether it is manual, dedicated, or other drive type autofocus, and cost performance is improved.

[0003]

In the AF single-lens reflex camera of the back focus control system, the amount of movement that can be adjusted between the front block and the rear block of the camera body is limited, so that the lens to be mounted can be photographed. It is difficult to cover the entire distance range. In particular, the shortest shooting limit becomes large on the long focus lens side. In addition, in AF operation with a manual focus lens, the position of the range ring of the lens is placed at an infinite position in principle, but since it is not fixed, it may be mounted at any position. . In such a case, the AF response range can be further limited. It is an object of the present invention whether or not the focus shift amount for AF response is within the variable range of the distance between the front block and the rear block of the camera body with respect to the current position of the distance ring of the mounted lens. , Ie A
An object of the present invention is to provide an in-viewfinder display device of an autofocus single-lens reflex camera capable of displaying whether or not it is within the F response range.

[0004]

In order to achieve the above object, a display device in a viewfinder of an autofocus single lens reflex camera according to the present invention includes a camera body front block including at least a taking lens and a lens mount for the taking lens. Based on AF information, a camera body rear block including at least a film opening, a front and rear block connecting portion that couples a distance between the camera body front block and the camera body rear block in an adjustable manner, An autofocus single-lens reflex camera comprising a lens mount of a front block of a camera body and an AF drive mechanism for adjusting a distance between openings of a rear block, and performing focusing by adjusting a flange back of the taking lens. , Outside the field of view in the viewfinder, the lens mount on the front block of the camera body A display unit including a display frame indicating a range in which the distance between the opening of the rear block and the rear block can be varied and a warning unit indicating the outside of the variable range are provided, and a focus position is obtained based on distance measurement data measured in advance, and the focus is determined. By displaying the position on the display unit, it is configured to display whether or not it is within the AF interlocking variable range.

[0005]

According to the above construction, the photographer can appropriately judge whether or not the camera is within the AF interlockable range for the lens currently mounted. Even if the AF interlockable range is out of the AF interlockable range, the AF interlockable range always exists at any position. Therefore, it is possible to change the position by adjusting the distance ring of the lens.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings. 1 is a schematic front sectional view showing an embodiment of a display device in a viewfinder of an autofocus single lens reflex camera according to the present invention and a circuit diagram showing a control circuit. Figure 2
1A is a partial plan cross-sectional view for explaining the details of the shape of the camera body front block in FIG. 1, and FIGS. 1B and 1C are examples of a connecting mechanism of the camera body front block and rear block in FIG. It is a schematic diagram for explaining. The front block A of the camera body includes an interchangeable lens 9, lens mounts 1 and A.
It is configured to include a grip 17 having an F drive mechanism 7 and a release button 14. The camera body rear block B includes an up-down mirror 13, a finder mechanism 5, an aperture 10, an exposure mechanism, a film feeding mechanism, and a distance measuring mechanism 3.

Light from a subject (not shown) passes through the interchangeable lens 9, the optical path is bent upward by 90 degrees by the up-down mirror 13, enters the finder mechanism 5, and becomes parallel light with respect to the main optical axis by the pentaprism 5a. It is bent so that it reaches the eyepiece lens 5b. Part of the subject light that has passed through the interchangeable lens 9 is also incident on the AF mirror 3a of the distance measuring mechanism 3, the optical path is bent downward, and the AF is performed via the AF lens 3b.
Reach the sensor 3c. The AF drive mechanism 7 is composed of a flange back drive motor 7a, an encoder 6 for detecting the number of rotations of the motor 7a, gears 7b and 7c, a lead screw 7d and a female screw 7e. The rotation output of the flange back drive motor 7a is transmitted to the lead screw 7d by deceleration via the gears 7b and 7c. Lead screw 7d
Is screwed into a female screw 7e provided on the base of the camera body rear block B, and the rotation of the lead screw 7d changes the distance between the camera body front block A and the rear block B in the optical axis direction. This allows the lens mount 1
And the distance between the aperture portion (opening portion) 10, that is, the flange back can be adjusted. The position where the distance between the front block A and the rear block B of the camera body is the shortest is the reference position where the focal point of the lens is at infinity,
It is possible to adjust from that position up to x mm.

Information indicating the positional relationship between the front block A and the rear block B of the camera body can be detected by the position detection switch 8. The sliding resistance 8a that constitutes the position detection switch 8 is fixed to the base portion of the camera body front block A, and the end portion of the contact 8b thereof is at the camera body rear block B.
It is fixed to the base of each. When the distance between the front and rear blocks A and B changes, the resistance value of the sliding resistance 8a changes accordingly, and a BF (back focus) position detection signal can be obtained. As the position detection switch, other than this, a switch for detecting a code pattern or another method may be used. FIG. 2 shows an example of a member connecting the front block A and the rear block B of the camera body. A pair of upper rails 16a and 16b and a lower rail 17a are provided on the upper and lower portions of the camera body front block A, respectively.
17b is provided. On the other hand, rollers 17a, 17b and 19a, 19b are provided above and below the rear block B, respectively. The rollers 17a, 17b and 19a, 19b are configured to roll on the upper surfaces of the upper rails 16a, 16b and the lower rails 17a, 17b when the AF drive mechanism 7 operates. With this configuration, the front block A of the camera body
The distance between the rear block B and the rear block B can be smoothly changed so that the load is not applied as much as possible. A bearing or the like that moves linearly may be used as the other connecting member.

A guide rod 26 is provided on the front block A of the camera body opposite to the lead screw 7d with the up-down mirror 13 in between. A guide hole 27 is provided in the camera body rear block B as a member for guiding this. The guide rod 26 slides in the guide hole 27 as the lead screw 7d rotates, and guides the camera body rear block B to the camera body front block A in cooperation with the lead screw 7d. This makes it possible to move the optical axes between the two blocks so that the optical axes do not shift and the aperture surface and the lens mount surface remain parallel to each other. A bellows 4 is provided between the end portions of both blocks where a gap is generated due to a change in the positional relationship to prevent light leakage.

Next, the configuration of the control circuit section will be described. A BF position detection signal is output from the sliding resistance 8a, an encoder signal is output from the encoder 6, and an (AF signal) is output from the AF sensor 3c, which are input to the AFCPU 20.
In the AF mode, the AFCPU 20 controls the BF drive circuit 21 based on the BF position detection signal, the distance measurement signal, and the encoder signal to drive the drive motor 7a to combine the rear block B with the front block A of the camera body. Move it to the focal position. When an AF / MF selector switch (not shown) is switched to the MF mode, the BF drive circuit 2
1 is controlled to move the rear block B to the position of the infinity focal length of the interchangeable lens 9, that is, the position where the distance from the front block A of the camera body is the shortest. The same applies when the power is turned off and when the release operation is not performed for a certain period of time.

A display section 24 for displaying the AF response range is provided below the field of view of the finder 23. The display unit 24 displays the AFCPU 20 via the display drive circuit 22.
The AF CPU 20 calculates the in-focus position based on the distance measurement data and displays the position on the display unit 24. FIG. 3 is an enlarged view of the lower side of the finder. A finder 23 having an AF mark 23a in the center
The lower display unit 24 includes a main body rear block movable range display frame 24c and out-of-frame non-response warning units (long-distance limit display part) 24a and front-and-bottom response non-warning warning units (short-range limit display unit) 24b. It is configured. When the AF response is possible, the display is within the main body rear block movable range display frame 24c, and is lit and displayed, for example, at 24d.
Further, when it is outside the AF response range, the long-distance limit display portion 24a or the short-distance limit display portion 24b is displayed in a blinking manner to give a warning.

FIG. 4 is a diagram for explaining the details of the display operation during the AF operation. FIG. 4A shows a camera body rear block movable range H, a camera body rear block movement amount Bf,
The optical path diagram of the lens showing the distance X to the subject and the focal length f is shown. FIG. 4B is a flowchart showing the display calculation operation. Release operation is performed (S401)
Then, the AF circuit unit is activated (S402). AFCPU2
In 0, the focus shift amount s is calculated based on the distance measurement data (S403). Then, it is determined whether the deviation amount s of the calculation result is on the close side (S404). If the deviation amount is on the close side, then it is determined whether or not H> m + s (S405). If H> m + s, it is within the AF response range, and the in-focus position is turned on within the main body rear block movable range display 24 (S406). If it is not H> m + s, it is outside the AF response range, and the short-distance limit display portion 24b blinks to issue a warning (S407). on the other hand,
When the deviation amount s is not on the close side, it is determined whether 0 <ms (S408). If 0 <ms, it is within the AF response range, and the in-focus position is lit in the main body rear block movable range display frame 24c (S406).
If 0 <m−s is not satisfied, it is outside the AF response range,
The long-distance limit display portion 24a flashes and issues a warning (S4).
09).

Next, several types of commercially available lenses will be described with reference to performance tables (listed at the end of the detailed description of the invention). The maximum amount of movement of the camera body rear block B is 10
It is assumed to be mm. To fix the distance ring of the lens to be mounted at an infinite position and make AF respond to the shortest shooting distance D ₀ of each lens, set the rear block B of the camera body to Bf.
Must move to the value indicated by (x). Since the maximum movement amount is 10 mm as described above, only the lenses A to N can perform AF response in the lenses listed in the table. For lenses with a longer focal length, the shortest shooting limit R
It can be understood that x is rapidly increasing. Therefore, when the shooting subject distance exceeds the shooting limit Rx, the short-distance limit display portion 24b blinks to give a warning. In such cases, the shadow caster can move the focal length by turning the range ring of the lens, so in most cases,
The focus position can be moved within the main body rear block movable range display frame 24c. Further, when the distance ring of the lens is set to a finite position and an image of infinity is to be captured, inevitably m-s <0, and therefore 24a blinks to give a warning.

In the above embodiment, the camera body front block A is provided with the grip portion, and the front block A is used as a reference,
The case where the flange back is adjusted by moving the rear block B has been described. However, the grip is provided on the rear block B, and the front block A is based on the rear block B as a reference.
It is obvious that the same operation is performed even if the is movable. Further, the AF drive mechanism may be provided in the rear block B accordingly. Further, if the film surface, the AF sensor surface, and the finder surface can be configured to be optically linked to each other in a conjugate positional relationship, the AF distance measuring mechanism, the finder mechanism, and the like need not necessarily be mounted on the rear block.

[0015]

As described above, according to the present invention,
In an autofocus single-lens reflex camera of the back focus control type, when the manual focus lens is AF-driven, it is possible to display whether or not the back focus movement amount for the AF operation is within the AF response range. In this way, displaying whether the AF response range is possible or not is very important in determining whether the AF operation can be performed when the manual focus lens is operated by the back focus control method. is there. If it is not within the AF response range, most lenses can be changed to the AF operation range by operating the range ring of the lens.

【table】

[Brief description of drawings]

FIG. 1 is a schematic front sectional view showing an embodiment of an in-viewfinder display device of an autofocus single-lens reflex camera according to the present invention.

2A is a partial plan sectional view for explaining the details of the shape of the camera body front block of FIG. 1, and FIGS. 2B and 2C are the camera body front block and rear block of FIG. It is a schematic diagram for explaining a connecting mechanism.

FIG. 3 is a diagram showing details of the finder of FIG.

FIG. 4A is a diagram for explaining each numerical value of a lens,
(B) is a flow chart for explaining the operation related to the display in the finder of FIG. 1.

[Explanation of symbols]

 1 lens mount 2 film surface 3 distance measuring mechanism 4 bellows 5 finder mechanism 6 encoder 7 AF drive mechanism 8 position detection switch 9 interchangeable lens 11 pressure plate 13 up-down mirror 15a, 15b lower rail 16a, 16b upper rail 17a, 17b roller 20 AFCPU 21 BF drive circuit 22 Display drive circuit 23 Finder 23a AF mark 24 Display section 24a Out-of-frame non-responsive warning section (far distance limit display section) 24b Out-of-frame non-response warning section (short range limit display section) 24c Rear block movable range display frame

Claims (2)

[Claims] 1. A camera body front block including at least a taking lens and a lens mount for the taking lens, a camera body rear block including at least a film opening, a camera body front block, and a camera body rear block. Between the front and rear blocks for adjusting the distance between the front and rear blocks, and an AF for adjusting the distance between the lens mount of the front block of the camera body and the opening of the rear block based on AF information.
An autofocus single-lens reflex camera configured by a driving mechanism, which adjusts a flange back of the taking lens, wherein the lens mount of the camera body front block and the rear block of the camera body are outside the viewfinder. A display unit including a display frame showing a range in which the distance of the opening can be changed and a warning unit showing the outside of the variable range is provided, and a focus position is obtained based on distance measurement data measured in advance. The display device in the viewfinder of the autofocus single-lens reflex camera characterized by displaying whether or not it is within the AF interlocking variable range. 2. The front block of the camera body is the A
2. An F drive mechanism and a camera holding grip having a release button are provided, and the camera body rear block is provided with a distance measuring mechanism, a finder mechanism, an exposure mechanism and a film feeding mechanism. Display device in viewfinder of autofocus single-lens reflex camera.