JPH0943504A - Focusing operation warning device of automatic focusing camera of moving film plane type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focusing operation warning device of an automatic focusing camera of a moving film plane type capable of quickly and effectively performing focusing operation display by mainly using manual focusing by means of the manual adjustment of a lens distance ring and using automatic focusing as an auxiliary means. SOLUTION: A defocusing amount to a focus is calculated by means of a range finding signal obtained based on the adjusting position of a distance ring of a photographic lens. A range finding CPU 36 displays whether or not the defocusing amount falls within a controllable range from the reference position of a back-focus in a warning display part 34. When it is within the controllable range, focusing feasible is displayed, the back focus is corrected by release operation by a photographer and an optical axis unit is brought to the focal position. Thereafter, a camera operating CPU 38 performs photographing operation and the optical axis unit is returned to the original reference position after completion of photographing. If not in the controllable range, warning display is done so that the photographer rotates again the distance ring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographic lens interchangeable camera, and more particularly to a focus operation warning device during focus adjustment of a back focus control type auto focus camera.

[0002]

2. Description of the Related Art In a warning device for a general lens drive type AF single-lens reflex camera, the amount of extension varies depending on the type of interchangeable lens. Therefore, for a finite shooting distance, the AF operation is performed by the distance ring drive of the lens at the first stage of release. If the adjustment capability of the lens is exceeded and the adjustment capability of the lens is exceeded, it is common to stop at that limit point and display a warning beyond the range. This warning device is A
After performing the F drive operation, there was a time delay because a warning was displayed.

[0003]

By the way, the conventional MF is based on the lens mount on which the conventional lens can be mounted and exchanged.
The main body is divided into front and rear parts to enable AF operation with a rear lens, and the so-called back focus control system ABF (Automati) by controlling the position of the rear film surface is used.
The present inventor has already proposed the c Back Focusing) method. In this back focus control, the unit including the rear film surface, which is a movable part, has a shooting function including the film chamber and includes many of the functions of the camera. There was a problem that speed and precision had to be controlled.

In order to solve this problem, when considering a model in which the movable range is not too large, the film chambers of the film cartridge and the take-up spool arranged on the left and right of the camera body are installed on the fixed side of the camera body, The AF sensor module on the movable side, a mirror box mechanism with a finder mechanism, a shutter, a film aperture, and an optical axis unit that has a function to shoot the optical axis, including the film pressure plate, hold the film and move it in parallel with the optical axis. We proposed a method to adjust the focus (Japanese Patent Application No. 6-24).
3448). With this method, the weight of the movable part can be reduced, and high-speed control is possible compared to the back focus control type AF camera originally proposed.

Further, as a recent tendency, as is said in general AF cameras, there is a demand for the creation of works that depict the emotions of the photographer in accordance with the situation of the subject, from photography left to the camera. Therefore, the emergence of a camera having a function capable of creating such a work is required. From the above point of view, we have proposed an ABF method that allows quick and easy simultaneous operation of manual focus adjustment and automatic focus adjustment and their switching (Japanese Patent Application No. 7-135979). This method satisfies the above-mentioned requirements, but some photographers tend to more thoroughly focus on manual adjustment by the lens distance ring and use autofocus as an auxiliary means. A camera suitable for use is required. An object of the present invention is mainly to manually adjust a lens distance ring, and when autofocus is used as an auxiliary means, a focus of a film surface moving type autofocus camera capable of performing a focus operation display quickly and more effectively. It is to provide an operation warning device.

[0006]

In order to achieve the above-mentioned object, the present invention provides a fixing portion mainly having a camera appearance having a lens mount for a photographing lens and a back cover for taking in and out a film, and a lens passing through the lens. An optical axis unit that has a finder mechanism, a distance measuring mechanism, an exposure mechanism, and a film opening portion that are arranged at the center of the optical axis, and is movable by a predetermined distance in the optical axis direction with respect to the camera appearance fixing portion, A film surface moving type autofocus camera in which a film feeding mechanism arranged on the left and right of the film opening portion is arranged in a camera appearance fixed portion, and a distance measuring operation is performed with respect to an adjusting position of a distance ring of a photographing lens, The defocus amount of the optical axis unit with respect to the in-focus position is calculated from the obtained distance measurement signal, while the optical axis unit is always positioned at the reference position for back focus. In addition, during the photographing operation, a focusing operation is performed by linearly moving the optical axis unit back and forth from the reference position in the optical axis direction, and a means for returning the optical axis unit to the reference position after the photographing is completed is provided. However, if the defocus amount calculated by the distance measuring operation is within the controllable range with respect to the back focus reference position, the in-focus indication is displayed, and if it exceeds the controllable range, the out-of-focus indication is displayed. It is configured to display a warning indicating that manual adjustment by the distance ring of the taking lens is necessary.
Further, in the above-mentioned configuration, the back focus correction in the in-focus display is activated after receiving a release signal for starting photography, and the shutter is released by a focus determination signal.

That is, the reference position of the optical axis unit, which is the movable part of the camera, is the distance from the lens mounting surface (flange surface) of the camera to the film opening position corresponding to the focal plane of the optical axis unit of the conventional lens flange. The back distance is set, and the habit of always returning to the reference position after the AF operation is given, and the focus point based on the position of the distance ring of the lens to be mounted and the distance measurement result is within the movable range of the back focus with respect to this reference position Whether or not it is judged is displayed.

According to the present invention, the movement habit is provided so that the back focus is always brought to the reference position except for the AF operation. Therefore, like the conventional manual focus camera, the distance ring of the lens can be seen while looking through the viewfinder to the subject. By adjusting, you can roughly adjust the focus. In this case, all you have to do is put it in the movable range, and if the photographer confirms the mark and presses the release button as it is, the back focus is corrected by the error amount for the focus adjustment made by the photographer, and the best focus is achieved. The shutter is released by being knocked down. Also, when the approximate focus adjustment by the photographer's lens distance ring is inappropriate in a range that cannot be corrected by the back focus adjustment, a warning is given. If you are given a warning, release it as it is,
The shutter is not released to prevent out-of-focus shooting.

[0009]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a plan sectional view for explaining the basic structure of a film surface moving type autofocus camera in which a focusing operation warning device according to the present invention is used. The position of the film surface is controlled by an optical axis unit which is a movable part for focusing. The mirror box mechanism 2 is provided on the right side of the mirror box 14 accommodating the mirror 13.
1 and a shutter unit 22 are provided. The optical axis unit B includes the mirror 13, the mirror box 14,
It includes a mirror box mechanism 21, a shutter unit 22, a film opening 10 and a pressure plate holding plate 19.

The fitting portions 14a to 14 of the mirror box 14
c is a slide rod 1 fixed to the camera body fixing portion A
The optical axis unit B is fitted to the optical axis units 1 and 12, and is slidable in the optical axis direction. A cartridge 17 and a spool 18 are housed in the film chambers 15 and 16 of the camera body fixing portion A on both sides of the film opening 10, respectively. The film feeding mechanism includes a cartridge 17, a spool 18, a drive source (not shown) for rotating the spool, and a gear group (not shown) for connecting them. In this AF camera, the movable amount of the flange back is reduced, and the cartridge 17 and the spool 18 are provided on the camera body fixed block A side. This reduces the weight of the movable part and reduces the weight load on the focus control.

Since this AF camera is capable of parallel operation of back focus control and manual adjustment of the lens distance ring of the photographer, the photographer sets the main subject of focusing to manual adjustment and uses auto focus as an auxiliary means. As described above, it is quite possible that there will be a tendency to use it. In consideration of such a tendency, if the reference position of the back focus is set to the flange back size of the lens and this is used as the starting point of the control, and the habit of always returning to this starting point of the reference after the back focus control operation is given, the AF operation In combination with the high speed of MF, the speed of MF shooting and the operability of shooting using both of these are further improved.

2 and 3 are schematic sectional views showing an embodiment of an autofocus camera in which the operation start position of the back focus control is set at a reference position. FIG. 2 is an example adopting a DC servo motor drive method. Reference numeral 3 shows an example in which a voice coil type linear motor drive system having a structure for providing a spring for returning to the BF reference position is adopted. In FIG. 2, the camera body fixing block A is an interchangeable lens 9,
It includes an AF drive mechanism 7 that drives the optical axis unit B in the AF mode using the lens mount 1 and the flange back drive motor 7a as a drive source. The optical axis unit B is configured to include the mirror box, the distance measuring mechanism 3 and the like as described in FIG. Light from a subject (not shown) passes through the interchangeable lens 9, the optical path is guided upward by the mirror 13, and enters the finder mechanism 5. In the finder mechanism 5, the penta prism 5a guides the light into parallel light with respect to the main optical axis and reaches the eyepiece 5b.

Part of the subject light that has passed through the interchangeable lens 9 is
The light is also incident on the AF mirror 3a of the distance measuring mechanism 3, the optical path is guided to the lower portion, and reaches the AF sensor 3c via the AF lens 3b. A flange-back drive motor 7a is provided below the camera body fixing block A, and the rotation output of the flange-back drive motor 7a is fixed to the motor shaft.
It is transmitted to the lead screw 7d via the gear 7c by b. By rotating the lead screw 7d, the female screw 7e moves back and forth, and the optical axis unit B can move. The optical axis unit B is moved to the in-focus position, and after the photographing is finished, it is driven by the flange back drive motor 7a to be moved to the back focus reference position.

Next, FIG. 3 will be described. The camera body fixed part A and the optical axis unit B have the same configuration as in FIG.
Only the drive mechanism part is different. The spring 28 has one end fixed to the camera body fixing portion A and the other end fixed to the optical axis unit B. A biasing force is applied to the optical axis unit B by the spring 28 in the direction of arrow c, and the end of the optical axis unit B abuts against the inner wall of the camera body fixing portion A and stops at the position of the BF reference distance, that is, the fixed position as shown in FIG. There is. An outer peripheral yoke 24 is fixed to the camera body fixing portion A, and a magnet 23 is installed at the center of the outer peripheral yoke 24. The magnet 23 has N-S poles arranged in the central axis direction. A center yoke 25 is further provided on the upper end of the magnet 23 (above the N pole).

On the other hand, a moving coil 27 is arranged coaxially with the center yoke 25 in a gap between the center yoke 25 and the outer peripheral yoke 24, and one end of the moving coil 27 is fixed to the optical axis unit B. A voice coil type linear motor is formed by the center yoke 25, the outer peripheral yoke 24, the magnet 23 and the moving coil 27.
By passing a current through the moving coil 27, the optical axis unit B moves in the optical axis direction against the spring 28 and reaches the focal point. When shooting is finished, the moving coil 2
The current of 7 is cut off, and the optical axis unit B has a spring 28.
The urging force of returns to the back focus reference position. In both the DC servo motor drive method and the voice coil type linear motor drive method, after the focusing operation, the flange back (back focus) of the photographing lens is always inevitable.
It returns to the reference position of and this reference position is made into the operation starting point.

FIG. 4 is a diagram showing an embodiment of a focus operation warning display in the viewfinder. This focus operation warning display is provided on the back focus control type AF camera (FIGS. 2 and 3) configured so that the optical axis unit is operated from the reference position for each focus operation. A warning is displayed whether or not the defocus amount calculated by the obtained distance measurement signal is within the focusable range from the back focus reference position. A focusable display unit 33, a front focus display unit 31, and a rear focus display unit 32 are arranged in the lower part of the finder. Focusable display 33 is ○
This is a display and is different from the one displayed when the focus is reached, which is used in the display of a general AF camera. In addition, the front pin display section 31 and the rear pin display section 32 on both sides
When is lit, it indicates that the setting position of the distance ring of the lens is inappropriate for the distance to the subject and the back focus adjustment movable range is exceeded. The direction of the arrow indicates the adjustment direction required by the distance ring, and when the front pin display section 31 on the left side is lit, the best focus position of the subject is farther than the BF adjustment movable range, and the distance ring is manually moved to the far side. It warns you to turn to the side, that is, to the right. Contrary to the above, lighting of the right rear pin display section 32 indicates that the best focus position is closer to the adjustment movable range, and a warning is given to turn to the left.

FIG. 5 is a diagram showing an example of a warning display in an actual photographing operation when the 135 mm lens is mounted. This figure shows a commercially available cz planar T * lens 135mm / F
2 shows the relationship between the AF operation range and the focus impossible display when No. 2 is attached. The horizontal axis represents the shooting distance and the vertical axis represents the adjustment position of the distance ring, and the AF response range with respect to the adjustment position of the distance ring is shown. In the case of perfect MF (manual focus without back focus control mechanism), since there is only one optimum focus position corresponding to each adjustment position of the range ring, the shortest shooting distance (1.5 m) from infinity to the range ring (1.5 m ) Can be represented by an AB straight line. This is called an MF line.

Now, assuming that the maximum movable amount of the back focus is 3 mm, the AF response range for each adjustment position of the distance ring of this lens is a range surrounded by ABCD. AD (∞ ~ 6m) if the distance ring of the lens is set to infinity
Although the response range is wide, it is shown that the response range becomes narrower when the range ring is adjusted to the finite side. A feature of this camera is that the photographer can arbitrarily adjust the range ring, so that the range ring can be adjusted according to the subject distance, as in the MF camera. A specific example will be described. Now, it is assumed that the adjustment position of the range ring is set to 20 m even though (i) the proper distance to the subject is 3 m. As is clear from FIG. 5, since it is outside the adjustable movable range of the BF, the rear pin display portion 32 of the left-pointing arrow lights up so as to rotate the distance ring to the left. That is, if the setting conditions of the subject distance and the distance ring are such that they fall within the area on the left side of the DC line, the distance ring warns that left-handed adjustment on the short distance side is necessary.

In accordance with this instruction, the photographer turns the range ring to the left to FH (5.3 m to 3 m), which is the AF response range.
It can be seen that the focusable display section 33 lights up and the proper focus can be obtained if the range is set to. Next, (ii) it is assumed that the adjustment position of the distance ring is 20 m even though the proper distance to the subject is 40 m. AB line (MF
Since it is the condition on the right side of the line), the front pin display portion 31 of the rightward arrow is turned on this time to give a warning to adjust to the long distance side. According to this instruction, the photographer turns the range ring to the right and adjusts the focus ring so that it falls within the range of EG (40 m to ∞), and the focusable display section 33 lights up to obtain the proper focus. In this way, the photographer only needs to perform an operation of roughly adjusting the distance ring so as to enter the ABCD area of the controllable range while watching the warning display for the subject distance, and the conventional AF is performed.
The in-focus position can be obtained much faster than with a camera.

FIG. 6 is a circuit block diagram showing an embodiment of a control circuit of a camera using the focusing operation warning device according to the present invention, and FIG. 7 is a flow chart for explaining the operation of the control circuit of FIG. . When the power of the camera is turned on and the control circuit is activated, the ranging CPU 36 first determines whether the optical axis unit B is at the reference position based on the reference position detection signal from the BF position detection SW 8 (see FIG. 1). A judgment is made (step (hereinafter referred to as "S") 701). If not completely returned, the motor drive circuit 35 is controlled to drive the drive motor 7a to move the optical axis unit B to the reference position (S702). This is because it is premised that everything is started from the reference position of BF. On the other hand, when it is confirmed that the photographer is in the reference position, the photographer determines which of the AF and MF photographing modes is selected (S7).
03). When MF is selected, the MF mode is obtained only by prohibiting the BF drive (S704) because the MF is located at the reference position which is the reference flange back of the taking lens, so the response becomes very fast.

In the AF mode, the AF sensor 3c
The defocus amount (Lx) from the BF reference position to the in-focus position is calculated from the obtained distance measurement signal (S705, S7).
06), it is determined whether or not the defocus amount of the focus is within the BF controllable range (S707). Distance measurement CPU3
6 drives the display drive circuit 37 based on the above judgment to control the display of the warning display section 34. If the adjustment of the distance ring of the lens is inappropriate and exceeds the controllable range, the front pin display section 31 or the rear pin display section 32 of the arrow warning that the manual adjustment of the distance ring is necessary in the viewfinder is displayed. The light is turned on (S708). According to the warning display, the photographer adjusts the distance ring so that it enters the center ABCD area shown in FIG. 5 (S709).

On the other hand, if it is within the controllable range, the focusable display portion 33 marked with a circle is turned on (S710). Therefore, if the photographer operates the release for photographing, the distance measuring CPU
The encoder 36 receives the information from the camera operating CPU 38 and outputs the amount of movement corresponding to the defocus amount (Lx) to the encoder 6
The motor drive circuit 35 is controlled while being detected by S to drive the drive motor 7a to move the optical axis unit B (S71).
1). Then, it is determined whether or not the focal point is reached (S7
12) If not reached, fine adjustment is performed (S713), and focus determination is performed again. When you reach the focal point in this way,
The distance measurement CPU 36 sends information to that effect to the camera operation CPU 38. The camera operation CPU 38 shifts to a series of operations such as mirror quick return operation, exposure operation, and film feeding photographing (S714). When the above shooting is completed, the distance measurement CPU
36 controls the motor drive circuit 35 based on the image pickup completion signal sent to return the optical axis unit B to the original BF reference position. As a result, one shooting operation is completed and the next shooting command is awaited.

The control circuit of FIG. 6 and the flow chart of FIG. 7 show an example in which the optical axis unit control is performed by a DC servo motor. However, when the voice coil type linear motor of FIG. 3 is used, a moving coil is used. When the current is cut off, the optical axis unit automatically returns to the FB reference position by the spring, so in the flowchart of FIG.
It suffices to cut off the F control current.

[0024]

As described above, according to the present invention,
As with the conventional exposure display, the circuit is activated to display in the viewfinder whether or not the adjustment position is within the controllable range for AF in the back focus control when adjusting the lens distance ring. Therefore, the photographer can perform the focusing operation accurately and quickly, and in combination with the small back focus correction working distance, the focusing operation is much faster than the current AF camera. There is an effect of doing.

[Brief description of drawings]

FIG. 1 is a plan sectional view for explaining the basic structure of a film surface moving type autofocus camera using a focusing operation warning device according to the present invention, in which an optical axis unit serving as a movable portion for focusing is used to move a film surface. The state to control is shown.

FIG. 2 is a schematic cross-sectional view showing an embodiment of an autofocus camera in which an operation start position of back focus control is set to a reference position, which is an example adopting a DC servo motor drive system.

FIG. 3 is a schematic cross-sectional view showing an embodiment of an autofocus camera in which an operation start position of back focus control is set to a reference position, and a voice coil type linear motor drive having a structure biased by a spring so as to come to a BF reference position. This is an example of adopting the method.

FIG. 4 is a diagram showing an embodiment of a warning display section in the finder.

FIG. 5 is a diagram for explaining a warning display example of actual shooting when a 135 mm lens is attached.

FIG. 6 is a circuit block diagram showing an embodiment of a control circuit according to the present invention.

FIG. 7 is a flow chart for explaining the operation of the camera using the focus operation warning device according to the present invention.

[Explanation of symbols]

 1 ... Lens mount 2 ... Film surface 3 ... Distance measuring mechanism 5 ... Viewfinder mechanism 7 ... AF driving mechanism 8 ... Position detection switch 9 ... Interchangeable lens 10 ... Film opening 13 ... Mirror 14 ... Mirror box 15, 16 ... Film chamber 17 ... Patrone 18 ... Spool 19 ... Pressure plate holding plate 20 ... Film 22 ... Shutter unit 23 ... Magnet 24 ... Outer peripheral yoke 25 ... Center yoke 27 ... Moving coil 28 ... Spring 30 ... AF sensor target display section 31 ... Front pin display section 32 ... Rear pin display unit 33 ... Focusable display unit 34 ... Warning display unit 35 ... Motor drive circuit 36 ... Distance measurement CPU 37 ... Display drive circuit 38 ... Camera operation CPU

Claims (2)

[Claims] 1. A fixing portion mainly having an outer appearance of a camera, which has a lens mount for a photographing lens and a back lid for taking in and out a film, a finder mechanism, a distance measuring mechanism arranged at the center of an optical axis passing through the lens, An optical axis unit that has an exposure mechanism and a film opening, and is movable in the optical axis direction by a predetermined distance with respect to the camera appearance fixing section is provided, and the camera appearance fixing section is arranged on the left and right of the film opening. A film surface moving type auto-focus camera with a film feeding mechanism, in which a distance measurement operation is performed at the adjustment position of the distance ring of the taking lens, and the obtained distance measurement signal causes the optical axis unit to defocus with respect to the in-focus position. While calculating the focus amount, the optical axis unit is always positioned at the reference position of the back focus, and the optical axis unit is set to the reference position during the photographing operation. From the position of the optical axis unit to the front-back direction to perform a focusing operation, and has a means for returning the optical axis unit to the reference position after the completion of photographing, and the defocus amount calculated by the distance measuring operation is If it is within the controllable range with respect to the reference position of the back focus, the focusable display is displayed, and if it exceeds the controllable range, the out-of-focus display is displayed and manual adjustment by the distance ring of the taking lens is required. A focusing operation warning device for a film surface moving type autofocus camera, which displays a warning to that effect. 2. The back focus correction in the focusable display is activated after receiving a release signal for starting photographing, and the shutter is released by a focus determination signal. A focusing operation warning device for the film surface moving type autofocus camera described.