JPH05107589A - Camera - Google Patents

Abstract

PURPOSE:To provide a camera in which exposure characteristic is hardly changed even by changing the size of a photographic image frame and appropriate exposure is always attained. CONSTITUTION:A photometric device incorporated in this camera capable of switching the size of the photographic image frame is constituted of a divided photomerty element 1 consisting of 1st 2nd and 3rd photodetectors 1a, 1b and 1c disposed on a finder optical system, amplifier circuits 2a, 2b and 2c, an A/D conversion circuit 3, an exposure arithmetic part 4 for calculating an exposure value based on the A/D convertion output of the circuit 3, and an exposure control part 5 which executes exposure control based on the calculated exposure value. In the exposure arithmetic part 4, the appropriate exposure value is obtained by changing the photometric characteristic of summation ratio (summation coefficient) showing importance degree in response to the switching of the size of the photographic image frame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera, and more particularly, to an exposure control device for a camera capable of switching a shooting screen size on a film.

[0002]

2. Description of the Related Art In recent years, a large number of cameras have been proposed which allow the size of the photographing screen to be switched with one camera.
Moreover, various specifications have come to be marketed. The shooting screen size switching camera of Japanese Patent Application No. 3-200877 proposed by the applicant of the present invention is as follows. The film loaded from the size and length of the film cartridge, the DX code, etc. is a normal 35 mm size film or a large size film. The screen size is switched by determining whether it is for screen shooting and moving the screen mask that determines the shooting screen size according to the judgment. If this camera is used, a larger photographic screen or a higher quality print can be obtained even for films having the same outer width.

On the other hand, in recent years, it has become possible to divide the light amount distribution on the screen to perform photometry, automatically perform exposure correction, and set the degree of emphasis on the pattern photometric value of each area in the screen. Cameras equipped with this photometric device have been widely used. The above-described conventional pattern photometric device incorporated in the camera has, for example, a photometric element composed of divided light receiving elements on which a subject image is projected, and three photometric elements on each photometric pattern shown in FIG. The pattern photometric output of the light receiving element is converted into a digital signal. The average subject brightness is calculated in consideration of the degree of emphasis on each pattern photometric output, the exposure value is calculated from that value, and the exposure control is performed by the exposure control unit configured with a shutter unit based on the exposure value. Is done.

[0004]

Considering the case where the above-mentioned conventional pattern photometric device is incorporated into the photographic screen size switching camera, if the focal length of the photographic lens is constant, the angle at which the photometric element gazes is also constant. is there. However,
When the size of the shooting screen is changed, the normal size screen in the normal size of 35 mm in FIG.
(Referred to as screen) on Gn, the photometric patterns Pa, Pb,
Although it is Pc, on the enlarged size screen (hereinafter referred to as B screen) Gb of FIG.
a ′, Pb ′, Pc ′, and the proportion of the area occupied by the photometric pattern to the photographic screen is relatively reduced as the screen is enlarged. For this reason, when comparing N-picture and B-picture photographed in exactly the same framing set to each size, the difference in the photometric characteristic of the weighting ratio indicating the degree of importance of the photometric value of each photometric pattern at the time of photography. As a result, the exposure state of the finally printed untrimmed photograph is different.

For example, when the output of the central photometric pattern Pa is lower than the output of the peripheral photometric pattern Pb by a certain amount or more as the backlight automatic correction, an algorithm for performing positive correction to prevent the central object from being blackened It is assumed that the photometric processing is performed by. At this time, a backlit subject having the size of the photometric pattern Pa at the time of shooting the N screen will extend to the area of the photometric pattern Pb ′ if the same framing is performed at the time of shooting the B screen. On the other hand, a backlit subject having the size of the photometric pattern Pa 'during B screen photography becomes smaller than the photometric pattern Pa if the same framing is performed during N screen photography. In such a case, even if the difference between the backlight subject and its surrounding brightness is at the backlight determination level, the backlight difference may not be determined because the brightness difference between the two patterns is reduced by switching the screen size.

Further, in addition to this, when performing the photometry in which the value of the photometric pattern Pa is emphasized in the center-weighted photometry mode, it is important to emphasize a relatively narrow range when the B screen is photographed rather than when the N screen is photographed. become. FIG. 18 is a diagram showing a photometric characteristic diagram showing changes in the weighting ratio K indicating the degree of importance of the photometric value of the photometric pattern in each shooting screen size in the center-weighted photometric mode. In the figure, the left side from the optical axis shows the photometric characteristic line KL1 of the weighting ratio K with respect to the photometric patterns Pa to Pc between the optical axis O and the screen edge GT in the screen during N screen shooting. On the right side of the optical axis, the photometric patterns Pa 'to Pc' between the optical axis O and the screen edge GT 'on the screen when the screen B is photographed.
Shows a photometric characteristic line KL2 of the weighting ratio K with respect to.
Then, when exposure control is performed, the weighting coefficient for multiplying each photometric value is obtained based on the weighting ratio corresponding to the photometric value of each photometric pattern. An exposure value is obtained from the weighted average luminance L obtained from the weighting coefficient and each photometric value, and exposure control is performed. For example, the photometric values of the photometric patterns Pa to Pc are set to La, Lb, and Lc, the weighting ratios Ka, Kb, and Kb indicating the degree of importance of each photometric value are set, and the weighting factors K1, K2, and K3 obtained from the weighting ratios are used. The weighted average luminance L is expressed by the following equation. That is, L = K1 × La + K2 × Lb + K3 × Lc (1). However, the weighting factors K1, K2 and K3 are expressed by the following equations.

K1 = Ka / (Ka + Kb + Kc) ……………… (2) K2 = Kb / (Ka + Kb + Kc) ……………… (3) K3 = Kc / (Ka + Kb + Kc) ……………… (4) The characteristic line KL1 ′ on the right side of FIG. 18 is a symmetrical line of the characteristic line KL1 at the time of N-screen photography for comparison.

As can be seen from FIG. 18, since the screen size is widened in the B screen, the width of the photometric pattern in the central weighted portion is relatively narrowed with respect to the screen edge GT ', and the characteristic line KL2 is smaller than the characteristic line KL1. Also becomes sharp, and a difference occurs in the photometric characteristics of both. When the photographer is familiar with the photometric characteristics of the camera as the ratio of the range visible in the viewfinder of the camera in N-screen photography, when attempting to perform B-screen photography, the N-screen photography and the B-screen photography described above are performed. Due to such a difference in the photometric characteristics, a problem occurs in which an exposure value different from the intended exposure value is calculated.

Furthermore, when the exposure value is calculated using a plurality of light receiving elements, the screen size can be switched to change the exposure value.
Since the ratio of each pattern to the entire screen changes substantially, with the same configuration and the same algorithm, it is possible that the sameness of the exposure calculation characteristics in the exposure value calculation when changing the screen size is lost. is there. The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a camera that can always obtain appropriate exposure by changing the photometric characteristics even by changing the size of the shooting screen.

[0010]

One of the cameras of the present invention is a changing means for changing the photographing screen size on the film surface, and a photometric means having a plurality of light receiving elements for measuring different areas within the photographing area. An exposure calculation means for performing an exposure calculation based on the output of the photometric means, and changing a weighting coefficient for a photometric value obtained from the plurality of light receiving elements according to the size of the photographing screen. To do.

Further, another one of the cameras of the present invention comprises the changing means, the photometric means, and the exposure calculating means, and the plurality of light receiving elements are provided in accordance with the photographing screen size. It is characterized by changing the selection of.

Still another one of the cameras of the present invention is:
It is characterized by comprising the changing means, the photometric means, and the exposure calculating means, and changing the corresponding angle of view of the plurality of light receiving elements according to the size of the photographing screen.

[0013]

In one of the cameras described above, when the photographing screen size is changed, the exposure value is determined by calculating the photometric value using a weighting coefficient suitable for the changed screen size. Also, in another of the above cameras,
When the shooting screen size is changed, a light receiving element suitable for the changed screen size is selected from the plurality of light receiving elements, and the exposure value is calculated based on the photometric output.
Further, in still another one of the cameras, when the photographing screen size is changed, the exposure value is calculated by changing the corresponding angle of view of the plurality of light receiving elements.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a block diagram of an electric circuit of a photometric device incorporated in a camera showing a first embodiment of the present invention. The present camera is a camera capable of screen switching photography between the normal size N-screen size photography and the enlarged B-screen size photography, and further uses the photometric device to perform photometry on a photometric pattern. Exposure control is performed by obtaining the average brightness based on a weighting coefficient obtained from an appropriate weighting ratio indicating the degree of importance in response to switching of the shooting screen.

As shown in FIG. 1, the photometric device is arranged on the finder optical system 30 (see FIG. 5) of the camera, and is a photometric means, which is the three first and second objects to which a subject image is projected. , 3 light receiving elements 1a, 1b, 1c, a divided photometric element 1, amplification circuits 2a, 2b, 2c for amplifying the photometric output of each light receiving element, and A / D for A / D conversion.
A conversion circuit 3 and an exposure calculation unit 4 which is an exposure calculation means and calculates an exposure value from the A / D converted photometric output.
And the exposure control based on the exposure value, and is configured by the exposure control unit 5 including a shutter unit and the like. In addition, the above three first, second,
The three light receiving elements 1a, 1b, 1c are assumed to perform photometry of the subject image on the photometric patterns Pa, Pb, Pc shown in FIG. 17, for example.

2 and 3 are a front view of the camera of this embodiment and a rear view with the rear lid removed. As shown in FIG. 2, on the front surface of the main body 10 of the camera, there are a photographing lens 12, a zooming operation switch button 11, an objective lens 33 of the finder optical system 30, a size switching switch button 13 between N screen and B screen, and the like. It is distributed. A release button 16 is arranged on the left side of the upper surface. The taking lens 12 is set to a size such that its image circle can correspond to the B screen. Then, as shown in FIG. 3, an eyepiece 34 of the finder optical system 30 is provided on the rear lid side of the camera, a mask opening 14 corresponding to the B screen, a shutter 15,
A cartridge loading chamber 17, a film winding chamber 29 and the like are arranged on both sides of the mask opening 14 with the mask opening 14 interposed therebetween. The film winding shaft 29 is provided in the film winding chamber 29.
A pressing roller 19 for pressing the film and reliably winding the film is provided. Further, the camera body 10
A photographing mask switching mechanism 20 which is a changing means for switching the photographing masks of the N screen and the B screen is incorporated therein, and the photographing screen size is determined by the positions of the mask frames 27 and 28 driven by the mechanism. ..

FIG. 4 shows the photographing screen mask switching mechanism 2 described above.
It is a figure showing the composition of 0. This mask switching mechanism 20
Is arranged in the camera body 10 as described above,
By operating the screen size switching motor 21, the B screen and N
The size of the photographic mask with respect to the screen is switched.
The rotation of the screen size switching motor 21 is controlled in accordance with the operation of the screen size switching switch button 13 by an instruction from a system controller (not shown). Output gear 2 of this switching motor 21
A pinion 23 is rotatably meshed with 2 and a pinion 24 is rotatably meshed with this pinion 23. The mask frames 27 and 28 that are switched and driven by the pinions 23 and 24 are formed so that L-shaped frame plates face each other and move in a diagonal direction with respect to each other. That is, both ends of both mask frames 27 and 28 extend diagonally to each other, and racks 27a and 28a are formed at the edge portions extending upward, respectively. And both racks 27a, 28a
Respectively mesh with the pinions 23 and 24. In addition, guide elongated holes 27b, 2 are provided in the extending portion in a diagonal direction.
8b and 27c, 28c are bored, and the respective guide elongated holes are fitted in the guide pins 25, 26 fixed to the main body.

The switching operation of the photographing screen mask switching mechanism 20 configured as described above will now be described.
It is assumed that the state of FIG. 3 or FIG. 4 is present. In this state, the mask frames 27 and 28 are retracted to the outside of the mask opening portion 14 and the photographing screen is masked by the opening portion 14, so that the B screen photographing size is set. Therefore, the screen size switching motor 21 causes the arrow λ to
When rotated in the direction of 1, the pinions 23 and 24 rotate in the directions of arrows λ2 and λ3, respectively, and the racks 27a and 28a of the mask frames 27 and 28 respectively move to the directions of arrows λ4 and λ4.
Move in the 5 direction. As a result, the mask frames 27 and 28 move inward relative to each other, and the inside of the frame becomes smaller, and N
A screen-size mask frame 20N is formed, and N-screen shooting is possible. In addition, the screen size switching motor 21
When is rotated in the direction opposite to the arrow λ1, the mask frames 27 and 28 move in the opposite direction to the above, that is, in the direction in which the inside of the frame increases, and are retracted to the outside of the mask opening 14 of the B screen size. The B screen photographing state is set.

FIG. 5 is a perspective view showing the structure of the finder optical system 30 in which the size of the field frame can be changed. This optical system is mainly composed of a real image type finder optical system consisting of an objective lens group 33, an erecting prism 31, and an eyepiece lens group 34. Field frame 32 for screen
The transmission type liquid crystal plate 32 capable of displaying a and the field frame 32b for the N screen is provided so that the field frame can be electrically switched. B of the transmissive liquid crystal plate 32
Field-of-view frame 32a during screen shooting and field-of-view frame 32 during N-screen shooting
The display of b is formed as shown in FIGS. 6A and 6B, respectively. The display switching is controlled by the system controller according to the screen size switching operation.

Further, as shown in FIG. 7, a photometric prism 36 is joined to the upper portion 31a of the erecting prism 31, and the photometric element 1 is disposed on the upper surface of the photometric prism 36. The photometric prism 36 and the prism 31
a is formed of the same material, and its joint surface 36a is a half mirror, and since the liquid crystal plate 32 and the photometric element 1 are in an optically conjugate position with the half mirror interposed therebetween, the liquid crystal The real image formed on the plate 32 is the photometric element 1
An image is also formed on the light receiving surface of. As described above, the photometric element 1 includes the three first, second, third light receiving elements 1a, 1b, 1c.
17A is a divided photometric element consisting of
As shown in, the photometry of the area corresponding to the photometric patterns Pa to Pc is performed. However, the angle of view to be measured is the angle of view at the time of N-screen shooting.

Next, the photometry and exposure control operation by the camera of the present embodiment having the above-mentioned configuration will be described with reference to the flow chart of FIG. 8 and the block diagram of FIG. First, the photographing mask is set to a desired screen size by the size switching button 13 shown in FIG. Then, when the release button 16 is pressed halfway to turn on the 1st release switch, the photometric mode process starts, and step S10 is started.
In 1 to step S103, the photometric patterns Pa to P
The photometric outputs of the first, second, third light receiving elements 1a, 1b, 1c for c are amplified by the amplifier circuits 2a to 2c, and A / D converted by the A / D conversion circuit 3. The output is input to the exposure calculation control circuit 4, and steps S104 to S106.
At, the luminances La, Lb, and Lc of the subject for each of the photometric patterns Pa to Pc are calculated. Then, step S1
In 07 to step S110, the weighted average luminance L is obtained by weighting each luminance based on the selected photographing screen size. That is, it is determined whether the selected shooting screen size is the N screen or the B screen (step S107).
In the case of the screen, the process proceeds to step S108, and in the case of the screen B, the process proceeds to step S109 to set the weighting factors K1 to K3 corresponding to each pattern adapted to the selected screen size. Then, in step S110, the luminance value La
~ Lc and weighting factors K1 to K3, a weighted average luminance L described later
Is calculated, and the exposure value is calculated based on the weighted average luminance L in step S111. Then, with the ON signal of the 2nd release switch by pressing the release button 16 in two steps, the exposure based on the exposure value is executed, and this processing is ended.

Next, the method of calculating the weighted average luminance L will be described in detail with reference to FIG. This camera is a camera that performs so-called center-weighted average photometry, and has weighting ratios Ka, Kb, and Kc that indicate the degree of importance of the photometric patterns Pa to Pc.
Are set to 1, 0.7 and 0.5, respectively. From these weighting ratios, the weighting factors K1, K2, and K3 by which the actual photometric values are multiplied can be obtained using the equations (2) to (4). FIG. 9 is a photometric characteristic diagram showing the weighting ratio with respect to the photometric value of the photometric pattern in each shooting screen size of the camera of the present embodiment. Like the above-described FIG. 18, the left side of the optical axis is N screen shooting. Characteristic line KL of the change of the weighting ratio K with respect to the photometric patterns Pa to Pc between the optical axis O and the screen edge GT on the screen at the time
11 is shown. On the right side of the optical axis, the photometric pattern Pa ′ between the optical axis O 1 and the screen edge GT ′ on the screen when the screen B is photographed
A photometric characteristic line KL22 showing the weighting ratio K to Pc 'is shown. The characteristic line KL11 'on the right side is a symmetrical line of the characteristic line KL11 at the time of shooting the N screens for comparison.

In the photometry device of the conventional example, the characteristic line KL2 of the weighting ratio K at the time of shooting the B screen has a characteristic line KL2 compared to that at the time of shooting the N screen. In order to prevent the photometric pattern P from changing as shown by the photometric characteristic line KL22 of the weighting ratio K in FIG.
The weighting ratio Kb 'to b'is changed from 0.7 to 0.8, and the characteristic line KL22 is changed to the photometric characteristic line KL at the time of N screen photographing.
Try to get as close as possible to 11. The weighting ratios Ka 'and Kc' for the other photometric patterns Pa 'and Pc' are also included.
Is set to 1,0.5 as in the case of shooting N screens.

The weighted average luminance L is calculated by using the weighting coefficient obtained from the weighting ratio by the photometric characteristic line KL11 at the time of N screen photographing, and from the weighting ratio by the photometric characteristic line KL22 at the time of B screen photographing. The weighted average brightness L is calculated by using the obtained weighting coefficient, the exposure value is obtained, and the exposure control is performed. In the weighted average luminance calculation process, as shown in FIG. 9, first, when the set size is N screens, the weighted ratios Ka, Kb,
Kc of 1, 0.7, 0.5 is applied as it is, and the weighting factors K1, K2, K are calculated from the equations (2), (3) and (4).
As 3, K1 = 1 / (1 + 0.7 + 0.5) = 0.455 K2 = 0.7 / (1 + 0.7 + 0.5) = 0.318 K3 = 0.5 / (1 + 0.7 + 0.5) = 0.227 is required. On the other hand, when the set size is B screen,
The weighting ratios Ka, Kb, and Kc for the B screen are 1,0.
8 and 0.5 are applied, and from the above formulas (2), (3) and (4), as weighting factors K1, K2 and K3, K1 = 1 / (1 + 0.8 + 0.5) = 0.435 K2 = 0.8 / (1 + 0.8 + 0.5) = 0.348 K3 = 0.5 / (1 + 0.8 + 0.5) = 0.217 is obtained.

In the photometric exposure control process of FIG. 8, the above-mentioned weighting factors corresponding to the photographing screen size are set in steps S108 and 109. Then, step S11
At 0, the weighted average luminance L is obtained from the equation (1) from the pattern photometric values La, Lb, Lc and the weighting factors K1, K2, K3, and if the exposure is controlled, the normal N-screen photography is performed. Even a photographer who is accustomed to the center-weighted average photometry using the weighting ratio can perform B screen photography with the same feeling.

As described above, in the camera of the present embodiment, the change of the photometric characteristic caused by the change of the size ratio of the photometric pattern to the entire screen due to the change of the screen size is completely changed by changing the addition ratio. Even if the average brightness is calculated by the same algorithm, characteristics very close to those before the screen change can be obtained. Therefore, the will and habit of the photographer are not impaired. It should be noted that in the present embodiment, the photometric element is
Although the divided light receiving elements are used, of course, the number of divisions may be any number, and the weighting ratio is not limited to the above value and can be a value convenient for photometry.

Next, a camera showing the second embodiment of the present invention will be described. This camera, like the camera of the first embodiment, is a camera capable of screen switching between normal size N screen size shooting and enlarged B screen size shooting, and includes a shooting lens and a viewfinder. The optical system and the photographing mask switching mechanism 20 as the changing means shown in FIG. 4 are incorporated. The photometric device built into this camera also has a photometric element composed of a plurality of light receiving elements. However, the photometric element on each pattern is selected by selecting the light receiving element corresponding to the switching of the photographing screen. Then, calculate the average brightness from the selected photometric output,
The exposure is controlled. However, the photometric element 41 (FIG. 11) which is the photometric means for projecting the subject image of the photometric device.
10), as shown in the layout of the photometric pattern in FIG. 10, a first light receiving element 41d having a photometric pattern Pd at the center of the image frame and a second photometric pattern Pe arranged outside the photometric pattern Pd. A light receiving element 41e, a third light receiving element 41f having a photometric pattern Pf outside the photometric pattern Pe and corresponding to the N frame outer frame Fn, and photometry outside the photometric pattern Pf and corresponding to the B screen outer frame Fb. And a third light receiving element 41g having a pattern Pg.
The ratio of the outer diameter of the photometric pattern Pd to the size of Pf is equal to the ratio of the outer diameter of the photometric pattern Pe to the size of Pg.

FIG. 11 is a block diagram of an electric circuit of the photometric device incorporated in the camera. In the photometric device, photometric outputs from the first, second, third and fourth light receiving elements 41d, 41e, 41f, 41g onto which a subject image is projected are amplified by amplifier circuits 42d, 42e, 42f, 42g, and A / It is digitally converted by the D conversion circuit 43 and input to the exposure calculation section 44 which is the exposure calculation means. Therefore, the corresponding photometric output is selected to calculate the exposure value, and the exposure control is performed by the exposure control unit 45 including a shutter unit or the like based on the exposure value.

Next, the photometry and exposure control operation by the camera of the present embodiment having the above-described configuration will be described with reference to the flow chart of FIG. 12 and the photometry patterns of FIGS. First, the photographing mask is set to a desired screen size with the size switching button. Then, when the release button is pressed halfway to turn on the 1st release switch, the photometric mode process starts. Whether the selected shooting screen size is the N screen or the B screen is determined (step S201). If the shooting screen size is the N screen, the process proceeds to step S202, and if the screen size is the B screen, the process proceeds to step S206.

In step S202, the photometric outputs of the first to third light receiving elements 41d, 41e and 41f are A / D converted.
Then, the photometric outputs of the second and third light receiving elements 41e and 41f, which are the photometric outputs related to the photometric patterns Pe and Pf, are added (step S203). The brightness L2 for the photometric patterns Pe and Pf is calculated by the added value (step S
204). Then, the brightness L1 of the pattern Pd is calculated by the photometric output of the first light receiving element 41d (step S20).
5) and proceeds to step S211. Here, the brightness L1
The central part of FIG. 13 is N in FIG. 13 (A) or (B).
The pattern Pd (hatched portion) in the center of the screen Gn corresponds. The peripheral portion showing the brightness L2 is shown in FIG.
3A or 3B corresponds to the portion to which the pattern Pe and the pattern Pf, which are the peripheral portion of the N screen Gn, are added. Here, FIG. 13B is a diagram in which the boundary line between the patterns Pe and Pf in FIG. 13A is not shown.
In addition, in FIG. 13A, B outside the N screen Gn is displayed.
The pattern Pf for the screen Gb is also shown by a broken line.

On the other hand, if the process proceeds to step S206, the photometric outputs of the first to fourth light receiving elements 41d, 41e, 41f, 41g are A / D converted. Then, the photometric patterns Pd and P
e, the photometric output of the first and second light receiving elements 41d and 41e,
Further, the photometric outputs of the third and fourth light receiving elements 41f and 41g related to the photometric patterns Pf and Pg are respectively added (steps S207 and S208). The brightness L1 of the central portion with respect to the photometric patterns Pd and Pe is calculated by the added value.
, And the luminance L2 of the peripheral portion with respect to the photometric patterns Pf and Pg are calculated (steps S209, 210). Then, the process proceeds to step S211. Here, the brightness L1
14A is a center portion of FIG. 14A or B of FIG.
The pattern Pd and the pattern Pe which are the central part of the screen Gb
The shaded area corresponds to the added area, and the peripheral area showing the brightness L2 is (A) in FIG. 14 or
The part to which the pattern Pf and the pattern Pg which are the peripheral parts of the B screen Gb of (B) correspond. Note that FIG. 13B is a diagram in which the boundary line between the patterns Pe and Pf in FIG. 13A is not shown. Thus, the brightness L1 in the central part and the brightness L2 in the peripheral part corresponding to each setting screen are
Therefore, the brightness L1 and the brightness L2 when the N screen is set and the brightness L1 and the brightness L2 when the B screen are set are the brightness L and the brightness L without distinguishing between the setting screens.
As 1 and L2, it is possible to use them for backlight judgment in post-processing and exposure value calculation. Next, in step S211, it is determined whether or not the backlight is on. This determination is to determine a backlit state when the difference between the central luminance L1 and the peripheral luminance L2 is 2 Ev or more. Then, when the brightness difference is less than 2 Ev and the backlight is not generated, the process proceeds to step S212, and the exposure value is calculated from the average value of the brightnesses L1 and L2 without correction. On the other hand, if the backlight is determined, the process proceeds to step S213, and the exposure value determined from the average value of the luminances L1 and L2 is plus-corrected by +1.5 Ev to determine the exposure value. Then, in step S214,
In response to the ON signal of the second release switch caused by pressing the release button in two steps, the process proceeds to step S215, the exposure based on the exposure value is executed, and the process is finished.

Since each pattern size is set to the dimension described in the pattern layout of FIG. 10,
The ratio of the size of the central part pattern (Pd + Pe) to the size of the B screen Gb for B screen shooting in FIG. 14B is the size of the N screen Gn for N screen shooting in FIG. 13B. It becomes equal to the ratio of the size of the central part pattern (Pd) to the height. Therefore, in the present embodiment, as described above, the central luminance L1 and the peripheral luminance L2 when the N screen is set, and the central luminance L1 and the peripheral luminance L2 when the B screen is set are as follows. , And can be used for back light determination in post-processing and exposure value calculation without distinction. Then, the processing can be performed in a state in which the change in the photometric characteristics due to the screen size switching is eliminated, and the photometric processing with high identity of the exposure calculation can be performed.

Next, a modification of the photometric device for the camera of the second embodiment will be described. In the second embodiment, the photometric output of each pattern is added after the A / D conversion, but in the modified example, the addition is not performed by calculation, and the photometric element 41 is selected by a predetermined value. This is done by adding outputs on a circuit. That is, FIG.
It is a block configuration diagram of a photometric device of the present modified example. First, the output of the light receiving element 41d is directly connected to the amplifier circuit 47a. Further, the output of the light receiving element 41e is input to the amplification circuit 47a via the analog switch 46a, and further input to the amplification circuit 47b via the analog switch 46b. Further, the output of the light receiving element 41f is directly output from the amplifier circuit 4
7b is input. Further, the output of the light receiving element 41g is input to the amplifier circuit 47b via the analog switch 46c. Then, the analog switches 46a to 46c described above.
Is controlled on and off in relation to the selection of screen size. The photometric pattern corresponding to each of the light receiving elements is the same as that of the second embodiment.

The output of the amplifier circuit 47a is used as the value corresponding to the central portion luminance L1 of the second embodiment, and is output from the A / D conversion circuit 4.
Input to 3. On the other hand, the output of the amplifier circuit 47b is the second
It is input to the A / D conversion circuit 43 as a peripheral luminance L2 corresponding value of the embodiment. Thereafter, similarly to the second embodiment, the exposure value is calculated and the exposure control is executed based on the central brightness L1 and the peripheral brightness L2.

In the photometric device of this modification having the above-described configuration, first, the analog switch 4 is used for N screen photographing.
Only 6b is turned on. Then, the output of the light receiving element 41d is taken in from the amplifier circuit 47a as the corresponding value of the central portion luminance L1. At the same time, the added output of the light receiving elements 41e and 41f is fetched from the amplifier circuit 47b as the corresponding value of the peripheral luminance L2, and the exposure value is calculated. On the other hand, at the time of shooting the B screen, the analog switches 46a and 46c are turned on and 46b is turned off. Then, the light receiving element 41
The added output of d and 41e is taken in from the amplifier circuit 47a as the corresponding value of the central luminance L1. At the same time, the light receiving element 41f
And 41 g are output from the amplifier circuit 47b as the corresponding value of the peripheral luminance L2, and the exposure value is calculated. As described above, in the present modification, the brightness of the central portion and the peripheral portion is obtained by a simple circuit, and it is not necessary to perform addition calculation of the photometric output in the exposure control unit, and the processing is simplified.

Next, a camera showing the third embodiment of the present invention will be described. The photometric device of the camera of the present embodiment changes the ratio of the size of the photometric pattern to the image frame based on the switching of the screen size, rather than controlling the electrical output as in each of the embodiments. The correction optical system is inserted in a photometric element section including a plurality of light receiving elements to change the angle of view of the plurality of light receiving elements for correction.

FIG. 16 is a layout diagram around the photometric element of this embodiment corresponding to the layout diagram of the photometric element of the finder optical system of FIG. On the photometric prism 36 having the half mirror portion 36a joined to the erecting prism 31a of the finder optical system, a photometric element 51 composed of a plurality of light receiving elements, which is a photometric device, is arranged. The photometric element 51
Is fixed to the rack 54 which is moved by the pinion 55 in the incident optical axis direction. In addition, the converter lens 5 fixed to the rack 56 driven by the pinion 57
2, when the photometric element 51 is retracted to the position 51 ', it can be inserted into the position 52' above the photometric prism 36. This converter lens 52 is inserted in the above position 52 'to change the corresponding angle of view of the light receiving element when the shooting screen size is switched to the B screen, and a subject image having a reciprocal magnification of the above screen size switching magnification is obtained. An image is formed on the light receiving surface of the photometric element 51.

In the camera of this embodiment constructed as described above, the converter lens 52 is in the retracted position during N-screen photography, and each photometric pattern of the photometric element 52 similar to that of the first embodiment. A subject image in the field frame of the N screen is formed on the top. Then, the exposure value is calculated based on the photometric value of each photometric pattern, and the exposure is controlled. On the other hand, when the photographing screen size is switched to the B screen, the photometering element 51 retracts to the position 51 'in conjunction with the operation, and the converter lens 52 is inserted to the position 52'. In this state, the field frame of the finder is enlarged for the B screen, but the angle of view of the photometric element 51 is changed by the converter lens 52, the subject image on the photometric element 51 is reduced, and the size of the frame is increased. The size is the same as the size when the N screen is photographed. Then, the ratio of the size of each photometric pattern to the size of the image frame has the same value as the ratio at the time of shooting the N screen. Therefore, in this photometric device, the same calculation process can be used for the exposure value calculation processing for the N-screen shooting and the B-screen shooting, and the processing in the exposure calculation unit becomes simple. However, the converter lens 5
When the light amount of the subject light may change due to 2, the correction calculation is necessary.

[0039]

As described above, the camera of the present invention uses the means for adjusting so that the photometric characteristics of the photometric element are less likely to change in response to the switching of the size of the photographing screen. Even if the shooting screen size is changed, the exposure characteristic is unlikely to change, and appropriate exposure can always be obtained, which has many remarkable effects.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a photometric device incorporated in a camera according to a first embodiment of the present invention.

FIG. 2 is a front view of the camera shown in FIG.

FIG. 3 is a rear view of the camera of FIG. 1 with a rear lid removed.

4 is a front view of a photographing screen mask switching mechanism of the camera shown in FIG.

5 is a perspective view of a finder optical system of the camera shown in FIG.

6A and 6B are front views of a liquid crystal display panel of the viewfinder optical system of the camera of FIG. 1, in which FIG. 6A shows a display state at the time of B screen shooting, and FIG. 6B shows a display state at the time of N screen shooting. Show.

7 is a side view of a photometry section of the finder optical system of the camera shown in FIG.

8 is a flowchart of a photometric exposure control process of the camera of FIG.

FIG. 9 is a photometric characteristic diagram of the photometric device of the camera shown in FIG.

FIG. 10 is a diagram showing a photometric pattern of a photometric element of a camera showing a second embodiment of the present invention.

11 is a block configuration diagram of a photometric device incorporated in the camera of FIG.

12 is a flowchart of a photometric exposure control process of the camera of FIG.

FIG. 13 is a photometric pattern on a shooting screen when shooting N screens of the 10 cameras described above, in which (A) is a diagram in which each pattern is distinguished and (B) is divided into a central portion and a peripheral portion. Figure shown.

FIG. 14 is a photometric pattern on a photographic screen when a B screen is photographed by the above-mentioned 10 cameras, in which (A) is a diagram in which each pattern is distinguished, and (B) is divided into a central portion and a peripheral portion. Figure shown.

FIG. 15 is a block configuration diagram of a modified example of the photometric device for the camera of the second embodiment.

FIG. 16 is a side view of a photometry section of a photometry device for a camera showing a third embodiment of the present invention.

17A and 17B are diagrams showing a photometric pattern for a photographing screen of a conventional camera, in which FIG. 17A shows a photometric pattern during N-screen photographing, and FIG. 17B shows a photometric pattern during B-screen photographing. ..

FIG. 18 is a photometric characteristic diagram of the photometric device of the camera of FIG.

[Explanation of symbols]

1, 41, 51 ... Photometric elements (photometric means) 1a, 1b, 1c, 41d, 41e, 41f, 41g ...
……………… Light receiving element (photometric means) 20 …………………………………… Shooting screen mask switching mechanism (means for changing screen size) 4,44 ………………………… Exposure calculation unit (exposure calculation means) K1, K2, K3 ………………… Weighting coefficient

Claims (3)

[Claims] 1. A changing means for changing a photographing screen size on a film surface, a light measuring means having a plurality of light receiving elements for measuring different areas within a photographing area, and an exposure calculation based on an output of the light measuring means. A camera, comprising: an exposure calculation means, wherein a weighting coefficient for a photometric value obtained from the plurality of light receiving elements is changed according to the size of the photographing screen. 2. A changing means for changing a photographing screen size on a film surface, a photometric means having a plurality of light receiving elements for measuring different areas in a photographing area, and an exposure calculation based on an output of the photometric means. A camera, comprising: an exposure calculation means, wherein the selection of the plurality of light receiving elements is changed according to the size of the photographing screen. 3. A changing means for changing a photographing screen size on a film surface, a photometric means having a plurality of light receiving elements for measuring different areas in a photographing area, and an exposure calculation based on an output of the photometric means. A camera comprising: an exposure calculation means, wherein the corresponding angle of view of the plurality of light receiving elements is changed according to the size of the photographing screen.