JPH0440699B2 - - Google Patents

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 aperture of the interchangeable lens is fully opened and the light transmitted through the 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 value 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 the lenses that are replaced and attached, and to the position of the light receiving element installed inside the camera. The former uses a preset aperture with an aperture adjustment ring, and the aperture value that is stopped down at the same time as shooting is based on the accuracy of the illuminance on the actual film surface with respect to the change in aperture adjustment value for each multiple placed on the aperture adjustment ring. The reason is that it does not give a significant multiple change. That is, 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 vignetting inherent to each lens, and are compared with an ideal or reference lens. This is because the effective illuminance on the film surface is significantly reduced at each aperture value of the interchangeable lens.
Therefore, since the effective value of the film surface illuminance decreases significantly, even if you try to use the photometry results to change the exposure multiple to the multiple aperture adjustment value,
Although the exposure time corresponding to the preset aperture adjustment value is given, proper exposure cannot be obtained. Errors caused by changes in illuminance on the film surface that appear differently for each individual interchangeable lens are called illuminance errors on the film surface.

On the other hand, in order to perform automatic exposure control and linkage with a light meter to provide proper exposure, the photometric element used to measure the light passing through the lens at maximum aperture is normally placed on the film surface. It is desirable to perform photometry at a position equivalent to the film surface, but if you try to actually measure light at the film surface, the photometric element literally becomes an obstacle to film exposure during shooting, so instead of this position, it is necessary to measure the light at a position equivalent to the film surface. Alternatively, it will be located at a position with a small difference in photometric upper distance from this. The photometric position equivalent to the film surface can be considered to be the position of the focusing plate where the light reflected by the reflecting mirror forms an image, and this position is preferable because it is co-located with the film surface, but on the other hand, this position is Since it not only obstructs the field of view but also interferes with the focusing operation, it is often used at the light exit end face of a reflective/inverting optical system such as a pentagonal roof cant prism placed on the focus plate, and through the viewfinder eyepiece. The circumferential side of the finder eyepiece was selected so that it does not obstruct the view of the field of view, and the photometric element is located here. 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. In addition, considering light absorption by the prism, etc., the photometry results will actually be given in a state slightly darker than the brightness of the film surface. Therefore, photometry cannot be 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, each of the above errors appears as a different amount of error in the actual photometric value at the maximum aperture, even if the lenses have the same maximum aperture value or the same focal length. . (Details of these errors are illustrated and explained in the specification of Patent Application No. 49771 filed in 1960.) In order to compensate for these errors and perform high-precision exposure control, aperture priority adjustment is For cameras using this method,
Depending on the aperture value to be preset, an information signal corresponding to the aperture adjustment value is transmitted from the lens side to the camera body's photometer, its circuit, or exposure control circuit using electrical correction means such as variable resistor control on the camera side. We communicate this information to the public to ensure appropriate exposure.

In this invention, regarding these two types of errors, the amount of error that occurs for each different type of lens that is replaced and attached is not used as a correction factor to be added to the apex calculation, but the narrowing down operation is performed from the camera body side to the lens side. This system compensates for the amount of movement of the operating system at the time of exposure, and thereby improves the exposure precision of automatic exposure control, which adjusts exposure time preferentially and narrows down the aperture accordingly. It is.

Prior to explaining the configuration of the present invention, in order to make it easier to understand, we will first explain the procedure for correcting the above-mentioned error in aperture-priority adjustment type cameras. A method of error correction using a narrowing down operation will be explained. 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 aperture adjustment 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 lenses have the same maximum aperture value, if the lens configuration and other factors differ, the effective value of the illuminance exerted on the film surface will differ at each aperture value, and lenses with the same maximum aperture value will have different focal lengths. In other words, in addition to the illuminance error on the film surface, the illuminance error also changes depending on the position of the light receiving part, so the resistance value selected by the aperture linking rod of each lens with respect to the variable resistor R at the open aperture value is It comes differently.

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, select one lens that is considered the most standard and use it as the standard lens.
Let's base this on the idea of making corrections for all other different lenses using this reference lens as a standard, and then selecting the resistance value at the maximum aperture value of the aperture linking rod of each lens.

Here, based on the illuminance error on the film surface and the illuminance error due to the position of the light receiving part derived with respect to the standard A lens (for example, open aperture value F1.4), follow the multiple aperture value scale arranged at equal intervals on the aperture adjustment ring. By configuring the aperture linking rod to be driven so that each adjustment aperture value selects an appropriate resistance value for the exposure calculation for the photometry circuit or the automatic exposure control circuit, the aperture linking rod of the reference A lens is The relative positional relationship between the variable resistor R on the camera body side, which selects the resistance value by presetting the aperture value, and the aperture adjustment ring a, which drives the aperture linking rod, is shown in A in FIG. With respect to this relative positional relationship, the aperture adjustment ring b of the different B lens with the same open aperture value F1.4 occupies the position indicated by the symbol B in Figure 1, and also has a smaller open aperture than the above B lens. The aperture adjustment ring c of the C lens having the open aperture value F4 occupies the position indicated by the symbol C in FIG. Of course, these positional relationships are shown by the positions of the aperture adjustment rings that each lens occupies when providing an open aperture, and are intended to facilitate understanding of the structural features of the present invention, which will be described later.

Lenses A, B, and C, which use this relative positional 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. A photometric signal corresponding to the actual film surface illuminance given at open aperture is transmitted to the calculation section of the photometric circuit or exposure control circuit, while each aperture adjustment value is adjusted by rotating the aperture adjustment ring from each of these starting points. This will correctly give a multiple exposure change.

This error compensation method uses the aperture priority adjustment method to provide aperture value information to the exposure control calculation circuit.
This method belongs to a method in which control is performed by replacing the resistance value selected by the adjusted aperture value, but looking at this compensation procedure from another perspective, it is possible to adjust the exposure time preferentially and then adjust it. Considering what kind of resistance value corresponds to the aperture to give the appropriate exposure for the given shutter speed, the resistance value determined by the result of the aperture has the above-mentioned film surface illuminance error and light receiving area. Therefore, by substituting this resistance value as a calculation element during the calculation for automatic exposure adjustment, it is possible to compensate for the error due to the difference in illuminance. This means that the amount of operation can be regulated. Therefore, on the premise that the aperture adjustment ring used in the aperture priority adjustment method will be used as is, an aperture adjustment ring for adjusting the minimum aperture value of the aperture adjustment ring of each lens to be replaced. By setting the position rotated by a certain angle (corresponding to a _v in the diagram, but in this case, a _v ≧0) from the rotation position of , as the adjustment position for automatic aperture control operation. Thus, a focusing operation is performed that compensates for the illuminance error on the film surface and the illuminance error in the light receiving section. The adjustment for this automatic aperture control position differs depending on each lens, but
The actual situation is as shown in FIG. That is, standard A
The automatic _aperture control position (Auto
position), the B lens which has the same maximum aperture value and minimum aperture value as the reference A lens is operated by compensating for the film surface illuminance error and the illuminance error in the light receiving section specific to that lens. The diaphragm automatic control position (Auto position) on the diaphragm adjustment ring equipped with the diaphragm linking rod will cause a deviation of ΔAvB from the reference A lens. Similarly, for the C lens, if the minimum aperture value is f32, there will be a deviation of ΔAvC, and when the minimum aperture value is f22 and the automatic aperture control position (Auto position) is determined, there will be a deviation of ΔAv'C. . In other words, these deviations generally ΔAv are:
Not only the deviation (-ΔRvB for B lens, ΔRvC for C lens) due to the difference in the starting point of the aperture adjustment ring determined by the maximum aperture value of the interchangeable lens and its unique characteristics, but also the same aperture adjustment for each lens. It will be understood that this also occurs depending on the minimum aperture placed on the ring.

Therefore, in the present invention, information is sent from the conversion lens side to the camera body side for automatic exposure control using an exposure time priority adjustment method (shutter priority method) to compensate for the deviation caused by the minimum aperture value that differs for each type of interchangeable lens. In addition to being transmitted as a signal, deviations such as -ΔRvB and ΔRvC (generally ΔRv), which are predicted for each interchangeable lens including the aperture value that differs for each interchangeable lens, illuminance error on the film surface, and illuminance error due to the position of the light receiving part, are also predicted. The aim is to compensate for this by replacing it with a correction value for the operating amount of the operating system that acts on the aperture member of the interchangeable lens from the camera body side, thereby realizing highly accurate automatic exposure control.

Based on the stance concept above, we will discuss the aperture calculation formula when the aperture adjustment ring is in the automatic aperture control position (Auto position).The exposure time priority adjustment method (shutter priority method) allows all units to be expressed as EV values. Av=Bv′+Sv−Tv+ΔAv−ΔAmin+1
... You can leave it as... In the above equation, Av is the aperture value, Bv' is the brightness value of the subject after passing through the lens, Sv is the sensitivity value of the film to be photographed, Tv is the shutter speed value for priority adjustment, ΔAv is the difference from the standard A lens, and ΔAmin is the difference from the standard A lens. It is the difference between the minimum aperture value and the minimum aperture value of each lens to be replaced, and is based on standard A as shown in Figure 1.
When the minimum aperture value of a lens is f22, if the minimum aperture value of the lens to be replaced is f22, ΔAmin = 0, and if the minimum aperture value of the lens to be replaced is f32, ΔAmin = -1.
This information is sent from the lens side to the arithmetic circuit in the camera body as a distance difference signal at the same time as the lens is replaced.

1 is the EV value given to the standard A lens at its maximum aperture of F1.4.

The aperture value Av obtained from the above equation is compensated for the film surface illuminance error and the light receiving section illuminance error. Incidentally, when the aperture value is preset by rotating the aperture adjustment ring and the aperture priority adjustment method is used instead of using automatic aperture control (Auto), the shutter speed is determined by Av and Tv in the above formula. Both have been transferred.

Tv=Bv′+Sv−Av+ΔAv−ΔAmin+1
The Tv value obtained here is obtained as the shutter speed, and the value can be used for exposure control and display in the viewfinder.

By the way, in automatic aperture control operation, a member that operates in conjunction with the shutter release on the camera body drives a release plate inside the lens, and when the release plate is activated, the aperture changes from the open state to a predetermined EV value. The Av value obtained from the above formula can be used as is because the amount of operation of the release plate and the amount of aperture are in a linear relationship and are given proportionally. cannot be used as a control value. In other words, as a calculated value, for example
When using the value of Av = 5 (f5.6) for aperture control, for a lens with an open aperture of F1.4 (Av = 1)
By stopping down the equivalent of 4EV, a f5.6 aperture can be obtained, and in this case, the maximum aperture of the lens is F4 (Av
= 4), by narrowing down the amount equivalent to 1EV
A narrowing down result of f5.6 (Av=5) is given. In other words, the EV equivalent amount required for narrowing down is the calculation result.
Since it is first obtained from the difference between the EV value and the EV value at the open aperture, the EV value Pv as a control amount is given by the following equation.

Pv=Bv+Sv−Tv+ΔAv−ΔAmin+1−
Amax = Av - Amax ... In the above formula, Amax is the EV value depending on the maximum aperture value that differs depending on the lens that is replaced.

As is clear from the above equation, the EV value as a control amount
Pv is affected by the maximum aperture value, which differs from lens to lens.
It can be seen that this governs the accuracy of the control amount Pv.
Therefore, each time a lens is replaced and installed, it is necessary to accurately send a signal specific to that lens to the camera body.

By the way, the brighter the lens is when used for photography, 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 range and 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 ensure that all of the various types of interchangeable lenses are exactly as described above. in the expression
Extracting the Amax signal and transmitting it to the camera body is difficult to implement considering the installation space, cost, operational reliability, and other aspects, and is even disadvantageous.

Therefore, in the present invention, errors in automatic control of the aperture value caused by such differences in the open aperture value, illuminance errors on the film surface inherent to the lens, and illuminance errors due to the position of the light receiving part are corrected by using the apex calculation. An adjustment means is provided to give a specific operation to a member that controls the aperture value without making corrections when the aperture value is adjusted, that is, an aperture drive member on the camera body side or a related member that brings the aperture value to a desired value. , I tried to correct this.

The specific operation of the adjustment means mentioned above is a part of the operation of the members in the operating system starting from the diaphragm drive member on the camera body side and ending at the diaphragm blades. This imposes an unrelated operation, and this uninvolved operation is hereinafter referred to as forward movement, and the above-mentioned unrelated operation is performed until the aperture blade's narrowing operation exceeds its open aperture value and begins to narrow the aperture diameter for light intensity control. The amount of displacement of the members of the movement system while performing the involved motion is hereinafter referred to as the amount of forward travel.

In the above formula, if we put ΔAv - ΔAmin + 1 - Amax = ΔRv ... and replace the value corresponding to ΔRv, which differs depending on each lens, with the amount of forward movement described above, the signal due to Amax, which is the EV value at the open aperture, is disappears from the above equation, and the EV value Pv as a controlled variable is given as Pv=Bv′+Sv−Tv...

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 open aperture value, the illuminance error on the film surface inherent to the lens, and the illuminance error due to the position of the light receiving part are eliminated.

FIG. 2 shows an example of a camera that automatically controls the aperture in accordance with the apex calculation formula. In FIG. 2, CA is a camera, and Bv indicates subject brightness. The amount of light transmitted through the lens and given to the photodetector PE due to the subject brightness Bv is a unique value depending on various factors such as the aperture of the lens, the light absorption rate of the lens material, internal reflection, pinetting, etc. As mentioned above. The output given by the light receiving element PE is logarithmically compressed by the Bv' generating circuit _C1 and sent to the arithmetic circuit _C2 as Bv'=Bv-(ΔAv-ΔAmin+1)...( ₁ ). In addition, an information signal Tv based on the priority adjusted exposure time (shutter speed) and an information signal Sv based on the sensitivity of the film used are introduced from the shutter speed adjusting member _C3 and the film sensitivity adjusting member _C4 , respectively. , an information signal Bv'+Sv-Tv (2) calculated by the calculation circuit _C2 is output.

On the other hand, when an interchangeable lens is attached to the camera CA and the aperture adjustment ring is rotated to adjust it to the automatic aperture control position (Auto position), ΔAv, which shows a unique value depending on each attached lens, is The output of ΔAv+1 (3), which is obtained by adding a constant 1 to this through circuit processing, is output from the correction signal member C ₅ and input to the arithmetic circuit C ₇ . By attaching the above lens, on the other hand, an information signal ΔAmin indicating the difference between the minimum aperture value unique to that lens and the minimum aperture value of the standard A lens is obtained from the minimum aperture signal member C ₆ from the calculation circuit C ₇ , and the arithmetic circuit C ₇ generates the output ΔAv−ΔAmin+1 (5) as a result of computation using these information signals.

This output is input to the arithmetic circuit _C8 together with the output of (2) above from the arithmetic circuit _C2 , and is calculated by the same arithmetic circuit ((2)+(5)) Bv′+Sv−Tv+ΔAv−ΔAmin+1=Av becomes.

If Bv' is replaced by equation (1), Bv + Sv - Tv = Av (6), and the apex display amount Av 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 simply indicates the aperture value that provides the appropriate exposure in accordance with the priority-adjusted exposure time (shutter speed), and does not indicate the amount of automatic control of the aperture. Already mentioned.
In order to perform aperture reduction in relation to the shutter release operation using the automatic aperture control amount Pv, the above output (2) output by the arithmetic circuit C ₂ and the aperture value of the lens must be used. Aperture signal generating member
The aperture value signal Av' obtained from _C10 is input to the comparator circuit _C11 for comparison, and when the output Av' reaches the above output Av, a signal output is given to the aperture control circuit _C12 to control the aperture control magnet EEmg. By opening the aperture, the aperture value can be controlled to the Av value, which is the result of the above calculation.

Based on this knowledge, FIG. 3 shows the aperture drive member on the camera body side when carrying out the method of the present invention, and
An example of a configuration in which a part of the operating system between the lens-side diaphragm blades is used as an adjustment means to cause the above-described forward movement before the diaphragm blades operate from the open state to narrow down the light amount control. This shows that.

In FIG. 3, S is a diaphragm blade forming an iris diaphragm, and 11 is a diaphragm blade operating ring for rotating a plurality of diaphragm blades S around each support pin 21, and the diaphragm blade operating ring 11 is a lens. Rotates around the optical axis relative to the stationary part of the lens barrel. Reference numeral 12 denotes a cam groove formed in the aperture blade operating ring 11, and the plurality of cam grooves 12 have respective aperture blades S.
A driven pin 22 is inserted. Further, a pin 13 is fixed to the side of the diaphragm blade operation ring 11 to engage 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. 1
1, a spring pressure acting in the direction opposite to the arrow mark in the figure is applied potentially, and the diaphragm operating ring 11 normally applies a force in the direction of fully opening the iris diaphragm. The position of the release plate 31 shown in the figure is
In this position, the aperture blade S occupies a position I indicated by a broken line.
That is, the inner edge of the diaphragm blade S is located inside the circumferential aperture indicated by the maximum aperture of the lens, and
When the diaphragm drive member or its relay member pushes up the diaphragm blade S in the direction of the arrow in the figure, as the diaphragm blade operating ring 11 rotates via the pin 13, the diaphragm blade S gradually moves so that its driven pin 22 moves into the cam groove. 12 and rotates around the support pin 21, and eventually reaches a position where its inner edge coincides with the circumferential opening indicated by the maximum opening. This position is indicated by a dashed line with a symbol. This position 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, from the position of the aperture blade S,
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 effect on 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 movement in the present invention, and the amount of displacement Lv is given as the forward movement amount. Although 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, it may also be set between the diaphragm drive member of the camera body and the release plate 31. Of course.

In order to give the amount of displacement Lv, which is the amount of forward movement, to each lens, for example, the B lens and the C lens, if Lv for the reference A lens is set as Lv=α, then for the B lens, Lv=α−ΔRvB,
Further, as described above, in the case of a C lens, Lv=α+ΔRvC.

However, these forward travel distances do not take into account the mechanical load on the operating system when performing the focusing operation in each interchangeable lens, and are based on the fact that there is no time delay caused by the operating mechanism system in the actual focusing operation. This is a premise. 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 signal until the aperture operation completely stops. .

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 terms of EV value, and the horizontal axis shows the time required for narrowing down. If a relative linear relationship is established between the amount of movement of the release plate 31 and the aperture value obtained by the aperture stop, the change in aperture value of the lens indicated by the amount of movement of the release plate 31 will always return to the open direction. Depending on the strength of the specially designed springs, the inertia of each moving member, the frictional load, etc., uneven characteristics such as an M lens with a fast operating speed, an average N lens, and a θ lens with a slow operating speed may occur. It does not occur uniformly. 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 from start to stop, and there is a tendency that the speed immediately after start is particularly slow, but this change is caused by the automatic control of the aperture by the release plate 31. From the perspective of the overall operation, the forward movement before the area of light amount control by aperture is slow, so even if it is considered to be an approximate linear change, it has almost no effect on the result, so here it is a linear change. It was clearly shown. In the figure, a straight line parallel to the horizontal axis indicates the forward travel amount Lv of the release plate 31 until the initial movement of the aperture blades reaches the aperture opening value.
After starting the release plate 31 for the M lens in the figure,
If a stop signal is issued to the release plate 31 at the time _M1 , the aperture blades actually stop at the time _M2 . Similarly, for the N lens, release plate 3
A stop signal at time N ₁ for 1 will stop the diaphragm blades at time N ₂ , and in the case of a θ lens, a stop signal at time θ ₁ will cause the diaphragm blades to stop at time θ ₂ . In other words, for any lens, there is a delay time from when the aperture stop signal is issued until the aperture blades stop.
This will result in Td. Therefore, in order to stop the actual aperture stop operation, an aperture stop signal must be issued as early as the delay time Td caused by the mechanical system, otherwise the aperture will be excessively reduced due to automatic control. This will result in

The present invention further proposes countermeasures for this point.

To explain again with reference to FIG. 4, there are differences in the amount of aperture operation during the delay time Td of the mechanical system for each lens, and when these are replaced by the amount of movement of the release plate 31, Lvm for the M lens, Lvm for the N lens Now, in the Lvn θ lens, it is indicated by Lvθ, and it is clear that the faster the operating speed of the lens, the larger the amount of subsequent aperture after receiving the stop signal.

This means that regarding the camera circuit that issues the aperture stop signal, based on the N lens which has an average operating speed, Lvn
If you set the aperture stop signal to be emitted as early as possible, the aperture will be stopped down by Lvn - Lvθ for a θ lens, and by Lvm - Lvn for an M lens. It becomes an obstacle. Also, regarding the forward travel amount Lv determined by the open aperture value for an N lens with an average operating speed, Lv=Lvn
Even if lenses have the same maximum aperture value, if the operating speed differs due to the mechanical configuration specific to that lens, the aperture control error indicated by the above-mentioned difference will appear. Therefore, for M lenses, Lv = Lvm, for N lenses, Lv = Lvn, and for θ lenses, Lv = Lvθ.If you set the amount of forward travel by taking into account the delay of the mechanical system for each type of lens, regardless of the slope of the traveling straight line. It is possible to correct the narrowing down error corresponding to the delay time Td.

Regarding cameras and lenses that use an automatic aperture control method that compensates for differences in the maximum aperture value of each interchangeable lens, and also compensates for differences in the aperture speed of each lens,
FIG. 5 shows an example of a preferred lens mounting structure configured to transmit unique signals from the lens side to the camera body side.

In Figure 5, the part indicated by the symbol CM is the lens mounting mount on the camera side, and the part indicated by the symbol LM.
The part shown with is the mount of the lens attached to the camera. Regarding the lens attachment mount CM and the lens mount LM, the drawings show the surfaces in close contact with each other when they are connected to each other.
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, and these have ON and OFF signals using binary codes. A counter-contact contact is provided to convey, which contact may also be used for conveying a current dominated by an electrical component, such as the resistance given by the minimum aperture, or other electrical quantities. . In the present invention, a mutual pair is provided for transmitting information determined from the lens side to the camera body side regarding the minimum aperture value that differs for each interchangeable lens and the automatic aperture control position (Auto position) determined by the minimum aperture value. Contact points 19 and 91 are provided to transmit a signal of ΔAmin 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 _C6 in FIG.

As is clear from the detailed description above, according to the present invention, the problem is caused by differences in the open aperture values of individual lenses that are exchangeably attached to the camera body, and changes in illuminance on the film surface that appear differently depending on each lens. 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 position of the light receiving part are easily corrected by taking into account the aperture operation, and the error is easily corrected by the amount specific to the lens. Since we have imposed a forward movement that is not involved in the aperture effect, it is possible to perform extremely high-precision aperture movement and highly accurate exposure control. Automatically performs highly accurate exposure control that takes into account the delay in mechanical operation that is controlled by the aperture operation speed and compensates for the advance movement of the aperture operation system, correcting all the differences in specifications that differ depending on the lens. This has the advantage that it can be carried out on a regular basis. Despite performing high-precision exposure control in this way, signal information based on the open aperture is transmitted from the lens side to the camera body via the lens mount, and this is used to adjust the circuit for exposure control. There is no need to incorporate it as an element, and the structure of the mount part, which is the part that connects the lens and camera, is simplified.
This has the advantage that it is useful for simplifying the configuration of the exposure control circuit, and does not require means for switching the open aperture value signal for correction, particularly when a zoom lens with F-number fluctuations is attached. Therefore, the overall structure is simple and small, and it exhibits the excellent feature of being able to provide a desired automatic exposure control camera with fewer failures while keeping production costs low.

[Brief explanation of the drawing]

FIG. 1 shows the basic principle of the present invention by showing 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. This is a conceptual diagram, and FIG. 2 is a schematic diagram schematically showing an automatic diaphragm control system, and FIG. 3 is an actual example of an adjustment means that provides forward movement of the diaphragm drive system that is not involved in the light amount control effect by the diaphragm. FIG. 4 is a characteristic diagram showing the delay in operation that occurs in the mechanical system during the aperture operation, and FIG. 5 shows a lens mounting mount of a camera body suitable for carrying out the present invention. This is a developed view of a portion of the lens that is relatively close to the mount. R...Variable resistor, A...Reference lens, B...
Other lens, C...Other lens, a...Aperture adjustment ring of reference lens A, b...Aperture adjustment ring of lens B, c
... Lens C aperture adjustment ring, CA ... camera, PE ...
...Light receiving element, C ₁ ...Bv′ generation circuit, C ₂ ...Arithmetic circuit, C ₃ ...Shutter speed adjustment member, C ₄ ...Film sensitivity adjustment member, C ₅ ...Correction signal member, C ₆
...Minimum diameter signal member, C ₇ ...Arithmetic circuit, C ₈ ...
...Arithmetic circuit, C ₉ ... Display circuit, C ₁₀ ... Aperture value signal generation member, C ₁₁ ... Comparison circuit, C ₁₂ ... Aperture control circuit, EEmg ... Aperture control magnet, S ... Aperture blade,
11...Aperture blade operating ring, 12...Cam groove, 13...
...Pin, 21... Support pin, 22... Driven pin,
31...Release plate, M...lens, N...lens,...lens, Td...delay time, CM...
Lens mounting mount, LM... Lens mount, 19, 91... Pair of contacts for transmitting the minimum aperture value signal.

Claims (1)

[Claims] 1. Apex calculation is performed based on exposure determining factors such as shutter speed information that is preferentially determined by the photographer's will, subject brightness information measured by TTL open metering, and film sensitivity information. In the shutter speed priority adjustment automatic exposure control method, which calculates an appropriate aperture value and controls the aperture according to this calculated aperture value, the difference in aperture value caused by the different aperture value for each individual interchangeable lens compared to the reference lens. The diaphragm blades correspond to illuminance errors and illuminance errors caused by the position of the light-receiving part that is not at a position equivalent to the film surface, and the delay in operation caused by the mechanism of the operating system that relays the operation of the diaphragm drive member to the diaphragm blades. An adjustment means is provided in a part of the operating system from the aperture drive member on the camera body side to the aperture blades on the lens side to reduce the stop error, and this adjustment means adjusts the error amount by adjusting the amount of error when the aperture blades start to stop down. A method for correcting aperture control in a single-lens reflex camera with interchangeable lenses, characterized in that each of the above-mentioned error amounts is mechanically corrected by taking into account a forward movement amount that is not involved in a change in light amount in a narrowing down operation of the aperture blades.