JPS63170630A - Correcting system for diaphragm control in single-lens reflex camera capable of exchanging lens - Google Patents

Abstract

PURPOSE:To improve the exposure accuracy for an automatic exposure control by compensating an error quantity generated at every different kind of lens by the quantity of a motion of an operating system at the time of executing a stopping-down operation toward a lens side from a camera body side. CONSTITUTION:The quantity corresponding to a difference which a full-aperture diaphragm value being different at every interchangeable lens, an illuminance error of a film surface generated in its full-aperture diaphragm value, and an illuminance error generated in relation to a position of a light receiving part have against a full- aperture diaphragm value of a reference lens and these errors is corrected by being replaced with the pre-running quantity which is not concerned in a light quantity control effect by stopping-down, by a release plate 3 for relaying an operation of a diaphragm driving member of a camera body side controlled by an operation of an exposure controlling circuit, to a diaphragm blade S of the lens side, and also, a diaphragm blade stop error corresponding to a delay of an operation generated due to a mechanism of an operating system for relaying the operation of the diaphragm driving member to the diaphragm blade S is added to the pre-running quantity and corrected. In such a way, a stopped-down operation of extremely high accuracy and an exposure control of high accuracy thereby can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION In a single-lens reflex camera with interchangeable lenses, when measuring light using the so-called TTL open metering method in which the lens to be replaced is fully opened and the light transmitted through the same lens is measured inside the camera, this method is used. If you directly link the light meter with the light metering value or perform automatic exposure control, a large error will occur between the exposure adjustment setting and the light metering value, so it is difficult to obtain shooting results with proper exposure. It is already known that it is difficult to obtain.

The causes of this error are mainly due to the optical characteristics of lenses that are accidentally replaced and attached, and those due to the position of the light receiving element installed inside the camera. The front sound is produced by the Prilet school, which uses an aperture adjustment ring! #
! The problem is that the calibration value, which is narrowed down at the same time as the shadow, does not give an accurate multiple change in the illuminance at the actual film plane with respect to the multiple change in the calibration value distributed on the calibration ring.

In other words, since interchangeable lenses have different lens materials, lens configurations, and assembly structures for each individual lens, they are affected by the light transmission characteristics and networking unique to each lens, and the effect of vignetting is particularly large at wide open apertures. This is because the effective illuminance on the film surface is significantly reduced at comparative values close to the open aperture.

As a result, the aperture aperture is small, for example f-number 5, 6L:1.
In the lower small aperture area, the illuminance changes almost evenly on the film surface in multiples according to the adjustment value for each calibration value step)
As the aperture approaches the maximum aperture (fi), the effective value decreases, and the illuminance on the film surface appears as a change in brightness that is far from a multiple change.At the maximum aperture (maximum aperture), the effective value of the illuminance on the film surface decreases significantly. Therefore, even if you try to make a multiple change in exposure to the multiple comparison adjustment value of a smaller aperture using the photometry result performed at this open aperture, it will still correspond to the preset aperture adjustment value. Therefore, proper exposure cannot be obtained.The error caused by the change in illuminance on the film surface, which appears differently for each individual interchangeable lens, is called the illuminance error on the film surface.

On the other hand, when linking with a light meter and automatically controlling exposure to provide proper exposure, the photometric element used to measure the light that passes through the lens under open conditions is normally placed on the film surface. It is desirable to perform photometry at the film plane, but if you try to actually measure the light at the film plane, the photometric element literally becomes an obstacle to film exposure during image transfer, so instead of this position, it is necessary to measure the light at the film plane. This means that the position is located at the position or the position where there is a small photometric difference between the two positions. The photometric position equivalent to the film plane is considered to be the position of the reticle where the light reflected by the reflecting mirror forms an image, and this position is preferable because it is coincident with the film plane. This not only obstructs the field of view but also interferes with the focusing operation, so in most cases the light exit end face of a reflective/inverting optical system such as a pentagonal roof cant prism placed on the reticle is used to pass through the finder eyepiece. The circumferential side of the finder eyepiece was selected so that it does not interfere with the clear view of the field of view, and the photometric element is located on this side. However, the position of this photometric element is deeper than the focal plate position, which is equivalent to the film surface, and is deeper by the length of the reflective and inverted optical path of the prism placed on the focal plate. Considering the light absorption by the prism, etc., the photometry result will actually be given in a state slightly darker than the brightness of the film surface. Therefore, photometry is not accurately equivalent to the brightness on the film surface, and the appearance of errors also changes depending on the difference in focal length of lenses that are replaced. This is called an illuminance error due to the position of the light receiving section.

In other words, even if the lenses have the same calibrated aperture value or the same focal length, each error in the upper alignment will appear as a different amount of error in the actual photometric value under the calibrated aperture condition. come. (Details of these errors can be found in 1968.
It is illustrated and explained in the specification of Japanese Patent Application No. 49771. ) In order to compensate for these w4 differences and perform high-precision exposure control, cameras with aperture priority adjustment system use a mechanical compensation device such as a cam f9 (for example, (It is shown in the patent application publication No. 53-33064.)
An information signal corresponding to the adjusted calibration value is transmitted from the lens side to the photometer or its circuit or exposure control circuit on the camera body side using electrical compensation means such as variable resistor control with a special configuration. I try to give the right exposure.

In this invention, the amount of error caused by each different type of lens that is replaced and attached with respect to these two types of errors is compensated for by the amount of movement of the operating system when performing the aperture operation from the camera body side to the lens side. The purpose of this is to improve the exposure accuracy of automatic exposure control, which is performed by adjusting the exposure time preferentially and narrowing down accordingly.

To illustrate the substance of the above concept in the present invention with a simple example, the A lens with an open aperture value of F1.4 is used as a reference lens, and the light transmitted through another X lens with an open aperture value of F1.4 is directed to a light receiving element. Assuming that only the amount of light entering the A lens at the comparative value of F1.7, the X lens will receive 0.5 EV of darker light than the A lens. AV on this paper -
Applying the apex operation of eV +Sv -Tv,
When the formula Av ' - By ' + 3v - Tv holds true for the standard A lens, for the X lens Av '' = (By ' -0, 5) + Sv - T
It becomes v.

As an example, 811 Sv-8 (EV) film sensitivity of the field
Sv -5 (EV) Exposure time Tv -8 (EV), 3v'=7
far.

(However, for the standard A lens, assuming that the effective illuminance of the light receiving element is about 1 EV lower, even if the open aperture is Fl, 4, By' -8 will not be achieved and Bv' -
As a result of calculation using these example values, the multi-values of AV, AV', AY" obtained from the above formula are Ay-5, Ay'
-4 (EV).

A value of AV"-3,5 (EV) is obtained. In this case, Av-5 indicates that the comparison value due to narrowing down is F5.6.

The amount of compensation for the movement of the operating system when performing the aperture operation for error compensation for the standard A lens is 1EV.
If this amount is given to the diaphragm drive member or its relay member as a forward motion amount that does not involve the light amount control effect, the diaphragm drive member's diaphragm motion amount will be substantially Av' +1.
-5 (EV) equivalent amount, and this causes the aperture faAV
-5 (corresponding to the comparison value F5.6), then with the X lens where the amount of forward travel is equivalent to IEV as above, Av ''
+ 1 = 4.5 (EV) Narrowed down to Av-4
, 5 (comparison value 4.5 due to aperture), resulting in a difference of 0.5 EV for the same subject. Therefore, the amount of forward movement of the X lens is 0 compared to that of the standard A lens.
．． If you set it to 5EV less (equivalent to 0.5EV), the aperture of the X lens will be ff1Av” + 1-4.5
EV becomes the position of AV-5 (comparison value F 5, 6), which coincides with the case of the reference A lens.

This is a part of the operating system that relays the operation of the comparison drive member that operates on the camera body steel to the aperture blades on the lens side to compensate for errors as required, and is not related to the light amount control by aperture related to the relay operation. This is intended to be corrected by imposing the amount of actuation as the amount of forward movement,
As a result, various necessary compensations such as differences in the aperture 1 (maximum aperture), illuminance errors on the film surface that differ for each lens, and illuminance errors related to the position of the light receiving part are performed accurately, and the narrowing down results are improved. The comparison value can always be made highly accurate.

Prior to explaining the configuration of the present invention, in order to make it easier to understand, the procedure for correcting the above-mentioned error in a camera using the aperture priority adjustment system will be explained. I will explain the method. In Fig. 1, R is a variable resistor provided on the camera body side, and the aperture linking rod, which is moved by a preset operation that rotates the calibration ring of each lens to be replaced, is set at its maximum aperture. A specific resistance value is selected and set for each variable resistor R. In this case, even if the lenses have the same maximum aperture, if the lens configuration and other factors are different,
The effective value of the illuminance on the film surface at the maximum aperture value is different, and if lenses with the same maximum aperture value have different focal lengths, in addition to the above-mentioned illuminance error on the film surface, there is also an illuminance error due to the position of the light receiving part. Because of this variation, the resistance value selected by the aperture linking rod of each lens for the variable resistor R at the maximum aperture value will be different.

Lenses that are interchangeably installed include lenses with the same maximum aperture value and different lens configurations, lenses with the same focal length but different maximum aperture values, lenses with the same maximum aperture value and different focal lengths, etc. Since there are a wide variety of lenses, we select the lens considered to be the most standard 11iI and use it as the reference lens. We then make corrections for all other different lenses using this reference lens as the standard, and then calculate the calibration rod for each lens. Let's base this on the concept of selecting the resistance value at the maximum aperture. Of course, even with the reference lens mentioned above (hereinafter referred to as the reference A lens, shown in Figure 1), at calibrated values at or near the maximum aperture, the brightness of the film surface was lower than the brightness based on these nominal calibrated values. 1. It only gives the effective value illuminance. In areas where the aperture is smaller than the reference value below these ranges, a multiple change in the reference value has the general characteristic that the illuminance on the film surface changes almost multiple times, and in addition to this characteristic, the photometric element Needless to say, it is affected by illuminance errors depending on the position of the parts. Standard A in this 1
Based on the illuminance error on the film surface and the illuminance error due to the position of the light receiving part derived from the lens (for example, open aperture fil! F 1.4), each adjustment is made according to the multiple calibration value scale arranged at equal intervals on the aperture adjustment ring. If the calibration value is configured to drive the calibration lever so that it selects an appropriate resistance value for exposure calculation for the photometry circuit or the automatic exposure control circuit, then the aperture coupling lever of the reference A lens will be set to the calibration value. The relative positional relationship between the variable resistor R on the camera body side, which selects a resistance value according to a preset value, and the aperture adjustment ring a, which drives the calibration rod, is shown in FIG. 1 (A). With respect to this relative inner position 11fllff, the aperture adjustment rings of eight different types of lenses having the same open aperture value F 1.4 occupy the positions indicated by the symbol (B) in Figure 1, and furthermore, from the above B lens. The diaphragm adjustment ring C of the C lens, which has a small open aperture value F4, occupies the position indicated by the symbol (C) in FIG. Especially like these! ! ! The relationship is shown by the position of the aperture adjustment ring that each lens occupies when giving its maximum aperture, and this makes it easier to understand the structural features of the present invention, which will be described later.

Such a relative internal position l! Lenses A, B, and C, which use this relationship as the starting point of the aperture adjustment ring, compensate for the illuminance error on the film surface and the illuminance error due to the position of the light receiving part occupied by the photometric element, and as a result, the actual values given at their open apertures are While transmitting the photometry signal corresponding to the film surface illuminance to the photometry circuit or the exposure control circuit's display section, it is also possible to accurately adjust the multiple exposure change based on each standard value by rotating the aperture adjustment ring from each of these starting points. It will be given.

This error compensation method belongs to a control method in which the calibration value information given to the exposure control path 11B is replaced by the resistance value selected by the adjustment calibration value using the narrowing penetration adjustment method. However, looking at this compensation procedure from another perspective, it is necessary to adjust the exposure time preferentially, and what resistance value corresponds to the aperture to give the correct exposure for the adjusted shutter speed. Considering this, the resistance value determined by the narrowed down result has been compensated for the film surface illuminance error and the error due to the illuminance a difference at the light receiving section, so this resistance value By substituting this as a calculation element during calculation for automatic exposure adjustment, it becomes possible to regulate the operation wJfR of automatic calibration motion control. Therefore, on the premise that the aperture adjustment ring used in the aperture-priority adjustment method is used as is, the aperture adjustment ring is used to adjust the minimum calibration value of the calibration adjustment ring for each lens that needs to be replaced. By setting the position U-turned by a certain angle (corresponding to ay in the figure, but in this case aV≧0) consisting of the rotational position of , as adjustment position 1 for automatic calibration control operation, the film surface can be adjusted. A narrowing down operation is performed that compensates for the illuminance error and the illuminance error in the light receiving section. Although the adjustment for such internal movement control position differs depending on each lens, the actual situation is as shown in FIG.

That is, in the standard A lens, move 111!1st 1! at a position separated by an amount corresponding to a from the scale point on the aperture adjustment ring a for presetting the minimum comparison value f22. (A
For the B lens which has the same open aperture value and minimum comparison value as the m-quasi A lens, compensation for the film surface illuminance error and the illuminance error in the light receiving part peculiar to that lens is performed. The internal movement control position (A auto position) on the calibration ring with the calibration link operated by the reference A
This will result in a deviation of ΔAVB for the lens. Similarly, for the C lens, if the minimum calibration value is f 32, there is a deviation of ΔAVC, and when the minimum calibration value is 122 and the calibration movement control position (A auto position) is determined, the deviation is ΔAVC.
There will be a deviation of 'C. That is, these deviations, ΔAV, are generally the deviations due to the difference in the starting point of the calibration adjustment ring, which is determined by the maximum aperture value of the lens to be replaced and its unique characteristics (-ΔRV B for the B lens).

It will be understood that in the case of a C lens, this occurs not only depending on ΔRye but also on the minimum calibration value placed on the respective calibration ring.

Therefore, in the present invention, the deviation caused by the minimum comparison value that differs for each type of interchangeable lens is transmitted as an information signal from the conversion lens side to the camera body side for automatic exposure control using an exposure time priority adjustment method (shutter priority method). At the same time, deviations such as ~ΔRvB, ΔRvC (generally ΔRv), etc., which are predicted including the maximum aperture value, illuminance error on the film surface, and illuminance error due to the position of the light receiving part, which differ for each interchangeable lens, are calculated by the replacement lens. This is compensated for by replacing it with a correction value for the operating amount of the operating system that acts on the diaphragm member from the camera body side of the lens, thereby realizing highly accurate automatic exposure control.

From the stance concept above, the aperture adjustment ring is at the internal movement control position (Aut).
Regarding the aperture calculation formula when the aperture is at position o), if all units are expressed as EV values using the exposure time priority adjustment method (shutter priority method), AV -3v' +5V-
TV+ΔAV−ΔAll1n+1 ・・・・・・・・・
・・・・It can be written as ■. In the above equation, Av is the calibration value By' is the brightness value of the subject after passing through the lens S■ is the sensitivity value of the film used for photography Tv is the shutter speed value to be adjusted with priority ΔAV is the difference ΔA from the reference A lens mtn is the reference A The difference between the minimum calibration value of the lens and the minimum calibration value of each lens to be replaced, as shown in Figure 1, when the minimum calibration value of the standard A lens is f22, the difference is If the minimum comparison value of the lens is f22, ΔAmi=O, and if the minimum comparison value of the lens to be replaced is f32, it is obtained as ΔAm1n=-1. It is sent to the circuit as a difference signal at the same time as the lens is replaced and installed.

1 is the standard A lens open aperture F1.4 EVla given to

The comparison value AV obtained by the above equation 0 is compensated for the film surface illuminance error and the light receiving part illuminance error. As a general rule, the calibration value can be set in advance by the presetting method by rotating the calibration adjustment ring, without using the internal motion control II (Auto) (in this case, the shutter speed is as above). Av and Tv of Equation 0 were transposed respectively.

Tv −3v′ +Sv −Av +ΔAv−ΔAw
in + 1 ・・・・・・・・・・・・・・・
The Tuff obtained in (2) is obtained as the shutter speed, and the value can be used for exposure control and display in the finder.

By the way, the automatic aperture control operation is performed by a member that operates in conjunction with the shutter release on the camera body side driving a release plate inside the lens, and when the release plate is activated, the aperture is opened until a predetermined EV value is given. It is obtained when the release plate moves and stops. Here, the operating amount of the release plate and the aperture control value have a linear relationship and are given proportionally, so AVla obtained from the above formula 0 can be directly used as the aperture control value. cannot be used as That is, as a calculated value, for example, Av
-5 (f 5,6>) for aperture control For a lens with an open aperture of F 1.4 (Ay -1), it is possible to obtain an aperture of f 5.6 by stopping down as much as JEV. In this case, the maximum aperture value of the lens is F4 (A
If y-4), by narrowing down the lEV equivalent old
The narrowing down result of r5.6 (AV-5> is given. In other words, the EV equivalent amount required for narrowing down is obtained only by the difference between the EV value of the performance result and the EV value of the open aperture value, so the control t[lff1 The EV value Pv is given by the following formula.

Pv −By +5v−Tv+ΔAV−ΔA win+
1-Amax leakage Av -Asax ・・・・・・・・・・・・・・・
...... ■In the above formula, A l1aX is the EVm depending on the open aperture value that differs depending on the lens to be replaced.

As is clear from the above equation, the EV value pv as the control amount is influenced by the aperture value rMtli, which differs from lens to lens, and it can be seen that this governs the accuracy of the control amount Pv.

Therefore, each time a lens is replaced, it is necessary to accurately send a signal specific to that lens to the camera body.

By the way, the brighter the lens is, the brighter the viewfinder image becomes, which is convenient for finding the focal point for focus alignment and for viewing the image condition. It is advantageous to be able to expand the aperture range and expand the exposure range that can be photographed, but on the other hand, there are restrictions on the optical performance and size of the lens, so it is necessary to accurately check all of the various types of interchangeable lenses. Extracting the A wax signal in the above-mentioned 0 type and transmitting it to the camera body is difficult to realize and is rather disadvantageous, considering the problems of the installation space, the cost, and the reliability of operation.

Therefore, in the present invention, the error on the automatic υ1wJ of the calibration value caused by the difference in the open aperture value, the illuminance error on the film surface specific to the lens, and the illuminance error due to the position of the light receiving part is calculated by performing the calibration value II1wJ. This is corrected by applying a specific operation to the member, that is, the diaphragm drive member on the camera body side or a related member that brings the required comparison value.

The unique operation mentioned above is a part of the interference of the members in the operating system starting from the diaphragm drive member on the camera body side and ending at the diaphragm blades, but is not involved in the operation of narrowing down the aperture from the open aperture value at all. This non-involved action is hereinafter referred to as forward movement, and the above-mentioned non-involved movement occurs until the aperture blade's narrowing operation exceeds its open aperture value and begins to narrow the aperture diameter to control the amount of light. The displacement of the movement system members during movement is hereinafter referred to as the amount of forward travel.

In the above formula 0, ΔAV −ΔA15in + 1 −A+sax
-Δ RV-...■, and convert the value corresponding to ΔRV, which differs depending on the individual lens, into the amount of forward travel described above. Then, the signal from A The EV value pV as a control amount is Pv By '+Sv -Tv ・・・・・・・・・
... It is given as ■.

To explain this using the C lens and B lens in Figure 1 as an example, the C lens has a forward travel amount larger than that of the A lens by ΔRvC, and the forward travel amount of the B lens is set to be smaller by ΔRvB. As a result, the distance difference due to the rf@discharge value, the illuminance error on the film surface specific to the lens, and the illumination error due to the position of the light receiving part are eliminated.

FIG. 2 shows an example of a camera that performs automatic IIJtall of schools based on such arithmetic expressions. In FIG. 2, CA is a camera, and Bv indicates the subject's sensitivity.

When the subject brightness is 3V, it passes through the lens and the light receiving element PE
As mentioned above, the amount of light given to the lens has a specific value depending on various factors such as the aperture of the lens, the light absorption rate of the lens material, internal reflection, and vignetting. The output given by the light-receiving element PE is logarithmically compressed by the Bv r generation circuit CI and By'=8v-(ΔAY-ΔAgain+1
)-(1) to the arithmetic circuit C2, and the arithmetic circuit C2 also receives an information signal TV based on the priority adjusted exposure time (shutter speed) and an information signal 3v based on the sensitivity of the film used, respectively. Information signals By' +Sv -Tv introduced from the speed adjustment member C3 and the film sensitivity adjustment member C4 and calculated by the calculation circuit C2, respectively.
・・・・・・・・・(Ri outputs.

On the other hand, attach the interchangeable lens to the camera OA and rotate its calibration ring to set it to the calibration automatic control position If (AutO position).
When adjusting to・・・
. . . The output of (3) is output from the correction signal member C5 and input to the arithmetic circuit C7. By wearing the lens, on the other hand, an information signal ΔA sin indicating the difference between the minimum calibration value specific to that lens and the minimum calibration value of the reference A lens is generated.
・・・・・・・・・・・・・・・・・・・・・・・・
(4) is given to the performance circuit C7 from the minimum diameter signal member C11, and the arithmetic circuit C? Then, the output of the result of calculation using those information signals is ΔAV−ΔAm1n + 1 ・・・・・・・・・・・・
・・・・・・・・・ (5) occurs.

This output is input to the arithmetic circuit C8 together with the output (2) from the arithmetic circuit C2, and is computed by the opening σ circuit to obtain ((,2) + (5) ')Bv' +5v-T
v+ΔΔV−ΔA1n+1=AV.

If B■' is replaced by formula (1) for the younger sister, 13v +Sv
−Tv=Av ・・・・・・・・・・・・・・・
(Q, and the apex display ff1AV of the aperture value can be obtained.

This Av value can be displayed in the finder using a display circuit C9 using a meter or the like. The information signal AV used for this display only indicates the calibration value that provides the appropriate exposure corresponding to the exposure time (shutter speed) that has been prioritized and does not indicate the amount of automatic control of the aperture. has already been mentioned.

In order to perform aperture reduction in relation to the shutter release operation using the automatic aperture v control amount pv, an arithmetic circuit C2 is used.
The comparison circuit C compares the output (2) outputted by the lens with the calibration value signal AV' obtained from the calibration value signal generating member C which corresponds to the calibration value of the lens.

When the output AV' reaches the above output AV, a signal output is given to the diaphragm control circuit CI2, and the diaphragm control magnet EEIICI is opened to control the comparison value to the AV value which is the result of the above calculation. can do.

Figure 3 shows some members of the operating system between the comparison drive member on the camera body side and the diaphragm blades on the lens side, when the diaphragm blades operate from an open state to narrow down the light amount control. This shows an example of a configuration in which a forward run occurs previously.

In Fig. 3, S is a diaphragm blade forming an iris diaphragm, and 1
Reference numeral 1 denotes an aperture blade operating ring for rotating a plurality of aperture blades S around each spindle pin 21, and the aperture blade actuator m11 rotates around the optical axis relative to a stationary portion of the lens barrel. Reference numeral 12 denotes a cam groove formed in the aperture blade operating ring 11, and a driven pin 22 mounted on each aperture blade S is inserted into the plurality of cam grooves 12. Further, on the side of the diaphragm blade operating ring 11, there is a bottle 1 that engages with a release plate 31 that is moved by an diaphragm drive member that is moved on the camera body side in connection with the release operation of the shutter.
3 is fixed to the diaphragm blade operating ring 11, and a spring pressure that acts in the direction opposite to the arrow in the figure is potentially applied to the diaphragm blade operating ring 11, and the iris blade operating ring 11 normally exerts a force in the direction of fully opening the iris diaphragm. is given. The position of the release plate 31 shown in the figure indicates the start position of the release plate 31, and in this position, the aperture blade S occupies the position (2) shown by the broken line. That is, the inner edge of the aperture blade S is located inside the circumferential aperture indicated by the maximum aperture of the lens, and when the release plate 31 is pushed up in the direction of the arrow in the figure by the aperture drive member or its relay member,
As the aperture blade operating ring 11 rotates via the pin 13, the aperture blade S gradually moves so that its driven pin 22 moves into the cam groove 1.
2 and rotates around the spindle pin 21, and eventually reaches a position where its inner edge coincides with the circumferential width indicated by the maximum opening. This position is indicated by the symbol ■ and a chain line. This position (2) occupied by the diaphragm blades S is the position of the diaphragm blades at the open aperture value, and the actual diaphragm is stopped by the subsequent rotation of the diaphragm blade operating ring 11. Therefore, the position of the aperture blade S■
During the period from to (3), the aperture blades do not play any role in controlling the amount of incident light, and the operation of the release plate 31 has no involvement in the actual aperture operation. That is, the movement of the release plate 31 from the start position to the displacement positions indicated by the dotted lines in the figure is the forward travel referred to in the present invention, and the displacement ff1Lv is given as the forward travel amount. This amount of forward travel is given to the correlated movement between the release plate 31 and the diaphragm blade S as in the case shown in the figure.
Of course, it may be set between the aperture drive member of the camera body and the release plate 31.

In order to give the displacement ff1LV, which is the amount of forward travel, to each lens, for example, the B lens and the C lens, if the LV in the reference A lens is LV=α, then in the B lens, it becomes LV−α−ΔRVB, and As mentioned above, in the C lens, LV-α+ΔRvC.

However, these forward travel amounts do not take into account the mechanical load on the operating system when performing the focusing operation in each interchangeable lens, and it means that there is no time delay caused by the operating mechanism system in the actual focusing operation. This is based on the premise that However, in actual operation, consideration must be given to the fact that there is a mechanical delay in the aperture operation mechanism for the aperture stop operation, especially after the aperture stop signal is received until the aperture operation completely stops. No.

FIG. 4 is a diagram showing the delay of this mechanical system. The vertical axis shows the amount of movement of the release plate 31 described above in EvM, and the horizontal axis shows the time required for narrowing down. If a relative linear relationship is established between the moving layer of the release plate 31 and the calibration value obtained by the aperture, the change in the lens calibration value indicated by the amount of movement of the release plate 31 is designed to always return to the open direction. Depending on the strength of the springs, etc., the inertia of each moving member, the frictional load, etc., uneven characteristics may occur such as an M lens with a fast operating speed, an average N lens, and a composite lens with a slow operating speed. Must not be.

The three characteristics shown in FIG. 4 are those of each lens. Strictly speaking, the movement of the release plate 31 itself changes its speed moment by moment from start to stop, and the speed tends to be especially slow immediately after start, but this change is due to the entire automatic control operation of the aperture by the release plate 31. From this point of view, the foregoing motion before the area of light m control by aperture is near and far, so even if it is regarded as an approximately linear change, it has little effect on the result, so in this case, it is a straight line. It was clearly shown. In the figure, a straight line parallel to the horizontal axis indicates the forward movement ff1LV of the release plate 31 until the initial movement of the aperture blades reaches the aperture opening value. The origin of the release plate 31 for the M lens in the figure! When a stop signal is issued to the release plate 31 at the time M1 after 11, the aperture blades actually stop at the time M2. Similarly, in the N lens, the stop signal applied to the release plate 31 at the time point Nt causes the aperture blades to stop at the time point N2, and in the case of the 0 lens, the stop signal at the time e+ causes the stop signal to stop at the time point N2.
The diaphragm blades will be stopped at this point. In other words, for any lens, there is a delay time Td from when the aperture stop signal is issued until the aperture blades stop. Therefore, in order to stop the actual aperture operation, the aperture stop signal must be issued as early as the delay time Td caused by the mechanical system, otherwise the aperture will be further reduced due to automatic control. become.

The present invention further proposes countermeasures for this point.

To explain again with reference to FIG. 4, there are differences in the amount of stop-down operation during the delay time d of the mechanical system for each lens, and when these are replaced by the amount of movement of the release plate 31, for the M lens, LVll N For lenses, l, vn 0 lenses are shown by LV combination, and it is clear that the faster the operating speed of the lens, the larger the subsequent aperture after receiving the stop signal.

This means that if the camera circuit that issues the aperture stop signal is set to emit the aperture stop signal lvn earlier than the amount of movement of the release plate 31, based on the N lens with an average operating speed. , → 1vn-L for lens
Ve is more, and in M lens L vs −
Since each aperture is narrowed down by L vn , this becomes an aperture control error and becomes an obstacle to providing proper exposure. Also, regarding the forward travel amount LV determined by the open aperture value for the N lens with an average operating speed, Lv, -
When set to the same ratio as LVn, even if lenses have the same maximum aperture value, if the operating speed differs due to the mechanical configuration specific to that lens, this will appear as an aperture control difference indicated by the above-mentioned difference. Therefore, for an M lens, LV -LVI, for an N lens, LV -1-Vn, and for a θ lens, LV -1,ve, and the delay of the mechanical system for each type of lens is sIi! ! By setting the amount of forward travel, it is possible to correct the narrowing down error corresponding to the delay time Td, regardless of the slope of the travel straight line.

For cameras and lenses that use the automatic control method, which compensates for differences in the maximum aperture value of each interchangeable lens and for differences in the aperture speed of each individual lens, the camera body is An example of a preferred lens mounting arrangement configured to transmit unique signals to each side is shown in FIG.

In FIG. 5, the part designated by the symbol CM is a lens mounting mount on the camera side, and the part designated by the symbol LM is a mount for the lens attached to the camera. Regarding the lens mounting mount CM and the lens mount LM, in the drawings, they are mutually connected! ! [This shows the side.

In other words, the camera lens mount CM is shown as seen from the front of the camera, and the lens mount LM is shown as seen from the back of the lens.
These are provided with counter-contact contacts to send ON and OFF signals according to a binary code, which carry currents or other electrical quantities dominated by electrical elements such as resistance values given by minimum calibration values. Sometimes used for. In the present invention, mutual communication is provided for transmitting information determined regarding the minimum comparison value and the internal motion control position 2j (Auto position) determined by the minimum comparison value for each interchangeable lens to be exchanged and attached from the lens side to the camera body side. Contact points 19 and 91 are provided to form a diaphragm, thereby transmitting a signal of ΔA win determined by the minimum aperture diameter from the lens side to the camera body side.

These pairs of contacts form part of the smallest diameter signal member Cs in FIG.

As is clear from the detailed description above, according to the present invention, the problem is caused by the difference in the maximum aperture value of the individual lenses that are exchanged and attached to the camera body, and the illuminance changes on the film surface that appear differently depending on each lens. After compensating for the illuminance error on the film surface and the illuminance error due to the position of the light receiving part caused by the specifications of the lens on the light receiving part position, automatic control of the comparison by the aperture operation is performed, and the I have a narrowing effect with light! Since we have imposed a forward motion that does not affect the lens, it is possible to perform extremely high-precision aperture operation and highly accurate exposure control. The advantage is that it takes into account the delay in mechanical operation that is controlled by speed and corrects it as a pre-travel layer in the aperture operation system, and automatically performs highly accurate exposure control that corrects all the differences in specifications that differ from lens to lens. There is. In this way, high-precision exposure 11. Despite performing II control, there is no need to transmit signal information from the lens side to the camera body side via the lens mount, and incorporate this as an adjustment element in the exposure control circuit. , the structure of the mount part that connects the lens and camera is simplified, and the exposure & 1J
It is useful for simplifying the configuration of the t[1 circuit and has the advantage that there is no need for means for switching the open aperture signal for correction, especially when a zoom lens with F-number fluctuations is attached.

Therefore the overall composition! ! ! It has the excellent feature of being able to provide a camera with automatic exposure control that is easy to use, has few failures, and maintains production costs at a low level.

[Brief explanation of the drawing]

FIG. 1 shows the basic principle of the present invention based on the relationship between the resistance value selected from a variable resistor by the diaphragm linking rod that interlocks with the diaphragm adjustment ring in various interchangeable lenses and the starting point of the diaphragm adjustment ring. FIG. 2 is a schematic diagram schematically showing the automatic aperture control system of the present invention, and FIG. 3 provides a forward running operation of the calibration drive system that is not involved in the light amount control effect by the aperture. FIG. 4 is a characteristic diagram showing the delay in operation that occurs in the mechanical system during the aperture operation; FIG. 5 is a rear view of the comparison mechanism showing an example; FIG. This is a developed view of a portion where the lens mount and the lens mount are relatively close to each other. R... Variable resistor A... Reference lens B... Other lens C... Other lens a... Reference lens A
Aperture adjustment ring b...Calibration adjustment ring for lens B C...Aperture adjustment ring for lens C OA...Camera PE...Photodetector CI...3v' generation circuit C2... Performance n circuit C3... Shutter speed adjustment member C4... Film sensitivity adjustment member CIi... Correction signal member C6
...Minimum diameter signal member C7...Arithmetic circuit C8.
...Arithmetic circuit Cg...Display circuit CI)...Comparison value signal generation member C11...Comparison circuit CI2...Aperture control circuit EEs+a...Aperture control magnet S...
・Aperture blade 11...Aperture blade operating ring 12...Cam groove 13...Bin 21...Support pin 22...Driven pin 31...Release plate M...Lens N.
...Lens combination...Lens Td...Delay time C
M... Lens mounting mount LM... Lens mount 19.91... Pair of contacts for transmitting the minimum comparison value signal Patent applicant Asahi Optical Co., Ltd. Figure 1 Figure 3 Figure 4 September 11, 1985 Kunio Ogawa, Commissioner of the Japan Patent Office 1, Indication of the case 1987 Patent Application No. 187327 2, Name of the invention Aperture in a single-lens reflex camera with interchangeable lenses Control amendment method 3, relationship with the case of the person making the amendment Patent applicant 2-36-9 Maeno-cho, Itabashi-ku, Tokyo (052) Asahi Optical Co., Ltd. Representative Toru Matsumoto 4, Agent Shinjuku-ku, Tokyo 2-14-1-5 Shimochiai, Date of amendment order Voluntary amendment 6, Subject of amendment Full text of the specification 7, Contents of amendment As shown in the attached document, we will supplement the specification 1 (no change in content).

Claims (1)

[Claims] The difference between the maximum aperture value that differs for each interchangeable lens, the illuminance error on the film surface that occurs at that maximum aperture value, and the illuminance error that occurs in relation to the position of the light receiving section is equivalent to the difference between the maximum aperture value of the standard lens and these errors. This amount is corrected by replacing it with a forward travel amount that does not affect the light amount control effect due to aperture by a release plate that relays the operation of the aperture drive member on the camera body side to the aperture blades on the lens side, which is controlled by the operation of the exposure control circuit. At the same time, an aperture blade stop error corresponding to a delay in operation caused by a mechanism of an operating system that relays the operation of the aperture drive member to the aperture blades is corrected by adding it to the forward travel amount. A correction method for aperture control in interchangeable single-lens reflex cameras.