JPH0440433A - Camera with automatic exposure controller - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a photometric error caused by a careless photometric action and the great deviation of an exposure value by comparing an actual F-number with a limit F-number, detecting the presence of the vignetting of a photometric sensor, and judging the inhibition or permission of an AE action. CONSTITUTION:An actual F-number convertor 23 converts a shifting quantity from an encoder for shifting 22 provided on the shifting mechanism 21 of a shift lens 1 to an actual F-number Fs, and outputs it to the comparator 25 of a camera main body side. A comparator 25 compares the obtained actual F-number Fs with a limit F-number F1 read out from limit F-number memory 24. Only when Fs <= F1 is satisfied the AE action of an exposure control means 15 is permitted. When it is not satisfied the comparator 25 inhibits the AE action of the exposure control means 15. Thus, a failure that the AE action is carelessly carried out, and a photograph having the deviation of the exposure value is taken, can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is for determining the optimal combination of shutter speed and aperture value from subject brightness output by a photometric sensor, film sensitivity, AE mode, etc. This invention relates to an automatic exposure control device.

[Prior Art] Various photometric optical systems and automatic exposure control devices for cameras have been proposed, one of which is shown in FIG.

In FIG. 4, the left side of the broken line shows the objective lens side, and the right side shows the camera body side. On the objective lens side, 1 is the objective lens, 2 is the focusing lens of objective lens 1, and 3
is an aperture, 4 is an aperture drive control circuit that controls the aperture drive based on the aperture drive amount sent from the camera body and the state of aperture 3, and 5 is data specific to the lens such as the aperture/minimum F number and focal length. This is a memory for stored lens data.

On the camera body side, 6 is a quick return mirror,
7 is a sub-mirror, 8 is a pentaprism, 9 is a photometric lens, 10 is a photometric sensor, 11 is an eyepiece, and 12 is a photometric sensor 10 to constantly obtain the optimum exposure control value based on the brightness information obtained from the sensor. object brightness calculation means,
13 is a film sensitivity reading means; 14 is an AE mode setting means for the user to set how to determine the shutter speed and aperture value; and 15 is an exposure value obtained from the subject brightness calculation means 12 and a film sensitivity reading means. exposure control means for determining the optimum shutter speed and aperture value from the film sensitivity obtained from 13 and the AE mode obtained from AE mode setting means 14;
6 is a shutter; 17 is a shutter drive control circuit for driving and controlling the shutter 16 in accordance with the shutter speed obtained from the exposure control means 15;

Between the aperture drive control circuit 4 and the exposure control means 15, the drive end signal and the aperture drive amount are transmitted via the connection terminal tl-t4, and from the lens data memory 5 to the exposure control means 1.
5, lens data is transmitted via a lens data output terminal t5 and a lens data input terminal t6.

The exposure control means 15 operates based on the exposure value obtained from the subject brightness calculation means 12 and the film sensitivity obtained from the film sensitivity reading means 13, according to a value set by the user using the AE mode setting means 14. It calculates the shutter speed and aperture value, transfers the calculated values to the shutter drive control circuit 17 and the aperture drive control circuit 4, and controls the drive timing of the shutter 16 and the aperture 3. The shutter drive control circuit 17 is the exposure control means 15
The drive time and timing of the actuator for driving the shutter are controlled by the shutter speed obtained from the above. When the driving is finished, a driving end signal is sent back to the exposure control means 15. Further, the aperture drive control circuit 4 controls the driving speed and number of times of driving of the actuator for driving the aperture based on the aperture value obtained from the exposure control means 15) and the state of the aperture 3. When the driving is finished, a driving end signal is sent back to the exposure control means 15. The above is the basic exposure control operation.

Next, the photometric optical system will be explained.

Light entering from the objective lens 1 is reflected by a quick return mirror 6, further reflected by a pentaprism, and enters an eyepiece 11. The photometric lens 9 and the photometric sensor 10 are located, for example, above the eyepiece in FIG. 4, and detect the intensity of light incident from the objective lens 1 and convert it into an electrical signal.

FIG. 5 shows the positional relationship between the objective lens 1 and the photometric sensor 10. In FIG. 5 (8), 18 is an exit pupil of the objective lens 1, and 10 is a photometric sensor.The photometric sensor 10 is located in the center of the exit pupil 18 of the objective lens 1 and is not obscured by the exit pupil 18. Therefore, accurate photometric values can be obtained.

[Problems to be Solved by the Invention] However, in the conventional example described above, the photometric sensor 1 is
If a part of 0 is vignetted at the exit pupil 18 of the objective lens 1, that is, if a part deviates from the exit pupil, the photometric sensor 10 cannot detect light in the vignetted part (deviated part). Therefore, it becomes impossible to obtain accurate subject brightness, and as a result, it becomes impossible to obtain an appropriate exposure value. Therefore, when configuring a general photometric optical system and automatic exposure control device as shown in FIG. No, Figure 5 (8)
The relative relationship is as follows.

In particular, when the photographic lens equivalent to objective lens 1 is replaceable, such as in an eye reflex camera, the size of the photometric sensor should be adjusted to match the one with the smallest exit pupil of all available photographic lenses. Since it is set at a certain angle, vignetting does not occur.

By the way, among the photographing lens systems of these conventional single-lens reflex cameras, there are special lenses called shift lenses and tilt lenses.

A shift lens is a lens that can move the optical axis of the photographic lens in parallel, and allows correction of perspective. A tilt lens is a lens that can tilt the optical axis of the photographic lens, and it makes it possible to tilt the surface of the object that can be focused, which is usually parallel to the film plane.

When such a shift lens or tilt lens is used as the objective lens 1 in Fig. 4, the exit pupil will be large if the lens has a certain brightness without shifting or tilting, and as mentioned above, the exit pupil will be large. Photometric sensor 10
Although no vignetting will occur, vignetting will occur in the photometric sensor 10 if the lens is shifted or tilted significantly. If you perform photometry carelessly under these conditions,
This may lead to metering errors, and in the worst case, there is a risk of taking a photo with a greatly incorrect exposure value. As a countermeasure, it is necessary to decide in advance not to include shift lenses or tilt lenses in the photographic lens series for cameras equipped with automatic exposure control devices, or to avoid using conventional tilt and shift lenses. One possible method is to devise a method in advance so that it cannot be attached to an automatic exposure camera. However, with this, when you want to perform shift lens or tilt lens photography, you have to prepare a manual exposure camera in addition to the automatic exposure camera, which is extremely inconvenient. Considering the further development of automatic exposure mechanisms of cameras in the future, such countermeasures cannot be said to be preferable. Furthermore, even though they are automatic exposure cameras, most of them allow manual exposure control by switching, so the problem is that these shift lenses and tilt lenses cannot be used at all. Furthermore, even if it is a shift lens or tilt lens,
If the amount of shift or tilt is within a certain small range, there is no vignetting of the photometric sensor and photometric operation is possible, so in that sense as well, the above-mentioned measures are not preferable.

[Object of the Invention] An object of the present invention is to solve the above-mentioned problems, and to solve the problem that when a shift lens or a tilt lens is attached as an objective lens, the photometry operation is performed carelessly, causing photometry errors, and
An object of the present invention is to provide an automatic exposure control device that can prevent large deviations in exposure values.

[Characteristics of the Invention] In order to achieve the above object, the present invention provides a method for adjusting the effective F-number of the objective lens, which is determined according to the direction and amount of parallel movement or inclination of at least a part of the optical axis of the objective lens. A real F number input terminal input from the side,
Limit F that stores the minimum F number required for automatic exposure operation (hereinafter abbreviated as AE operation) to be performed normally.
A number storage means and a determination means for comparing the actual F-number and the limit F-number before operating the exposure control means and prohibiting the operation of the exposure control means when the former is larger than the latter, The present invention is characterized in that the presence or absence of vignetting of the photometric sensor is detected by comparing the actual F-number and the limit F-number, and it is determined whether the AE operation is prohibited or permitted.

[Embodiment of the Invention] FIG. 1 is a block diagram showing an embodiment of the present invention when a shift lens is installed, FIG. 2 is a flowchart showing the AE operation thereof, and FIG. It is a figure which shows the vignetting of the photometry sensor in the illustrated example.

First, FIG. 3 will be explained.

FIG. 3(8) shows the positional relationship between the exit pupil 19-1 of the shift lens and the photometric sensor 1o when the shift amount is O, and there is no vignetting in the photometric sensor 10. Figure 3 (B
) is the exit pupil 19- when the sensor is shifted to a certain extent.
2, and even in this state, vignetting of the photometric sensor 10 has not yet occurred, so the photometric operation is performed normally. FIG. 3(C) shows the exit pupil 19-3 when shifted further, and the lower part of the photometry sensor 10 is vignetted, so the photometry operation is not performed normally. It is.

Now, in each shift state, the exit pupil 19-1 of the shift lens
, 19-2, and 19-3, and whose center is the optical axis of the camera, are 20-1.2, respectively.
0-2.20-3, and the F numbers corresponding to these inscribed circles are called the real F numbers Fs in each shift state.As the shift amount increases, the real F numbers Fs also become thicker. . On the other hand, if the minimum maximum F-number of the objective lens required for normal photometry operation is the limit F-number F1, as long as Fs≦F1 (1), normal photometry operation will occur even with a shift lens. It can be said that it is possible. Regarding the tilt lens, if the effective F-number Ft in each tilt state is defined in the same way, normal photometry operation is possible when Ft≦Fl (2).

Therefore, in order to prevent exposure control from being performed inadvertently when a shift lens or tilt lens is attached to a camera equipped with an automatic exposure control device, the amount of shift or tilt of the objective lens must be adjusted. The actual F numbers Fs and Ft corresponding to the above may be compared with the limit F number F1 determined by the AE system, and the AE operation may be prohibited when conditional expression (1) or (2) is not satisfied.

FIG. 1 is a block diagram of the actual flow of the present invention to realize this, and is an improved version of FIG. 4. Since there is no physical difference between a shift lens and a tilt lens in applying the present invention, a shift lens is shown in FIG. be.

In FIG. 1, 1 is a shift lens, 2 is a focusing lens of the shift lens 1, 21 is a shift mechanism of the shift lens 1, 22 is a shift encoder for detecting the shift amount of the shift mechanism 21, and 23 is a shift encoder for the shift lens 1. This is an actual F-number converter that converts the shift amount of F into the previously defined actual F-number Fs.

24 is a limit F-number memory that stores the limit F-number F1, etc., and 25 is a comparison result between the actual F-number Fs sent from the actual F-number converter 23 on the objective lens side and the limit F-number F1. This is a comparison circuit that prohibits or allows the AE operation of the exposure control means 15 depending on the situation.

From the actual F-number converter 23 to the comparison circuit 25, the actual F-number Fs is transmitted from the actual F-number output terminal t7 to the actual F-number input terminal 78.

The exposure control means 15 controls the exposure based on information from the subject brightness calculation means 12, the film sensitivity reading means 13, the AE mode setting means 14, etc. in the same way as explained with reference to FIG. In the example, prior to this,
Determine the presence or absence of pupil vignetting.

That is, the actual F-number converter 23 is a shift encoder 2 provided in the shift mechanism 21 of the shift lens 1.
The shift amount from 2 is converted into the above-mentioned actual F-number Fs, and outputted to the comparison circuit 25 on the camera body side. The comparison circuit 25 compares the obtained actual F-number Fs with the limit F-number read from the limit F-number memory 24, and allows the AE operation of the exposure control means 15 only when the above-mentioned formula (1) holds true. . If equation (1) does not hold, the comparison circuit 25 prohibits the AE operation of the exposure control means 15. As a method of prohibiting, no matter what mode the AE mode is set by the AE mode setting means 14,
There is a method of forcibly switching to manual mode,
If the mode set by the E-mode setting means 14 is other than manual mode (manual exposure mode), a method of prohibiting the release operation can be taken.

In practice, the exposure control means 15 and the comparison circuit 25 are often incorporated together in one microcomputer, and a flowchart showing the flow of processing in this case is shown in FIG.

Figure 2 (8) shows a method of prohibiting AE operation by forcibly switching to manual mode, and Figure 2 (B) shows a method of prohibiting release operation when AE mode is other than manual mode. The flowchart is shown below. Such a microcomputer often incorporates, for example, control of a photometric system in addition to the AE operation, and on this premise, only the AE operation will be described.

In FIG. 2 (8), when switching from control other than AE operation to AE operation, first, in step (2), lens data is read from the lens data memory 5. Here, the lens data is a set of a series of lens-specific data including the aforementioned substantial F-number Fs. Next, in step ■,
A comparison is made between the actual F-number Fs and the limit F-number F1, and if the condition of the above-mentioned equation (1) is satisfied, the process proceeds to step (2), where the exposure value is read from the subject brightness calculation means 12. In step (2), the film sensitivity is read from the film sensitivity reading means 13), and in step (2), the AE mode set by the AE mode setting means 14 is set. In step ■, the shutter speed and aperture value are calculated from the exposure value read in step ■, the film sensitivity read in step ■, and the AE mode read in step ■.In step ■, these are displayed and the AE operation is Canceled, A
Shift to control other than E operation. On the other hand, in step (2), if equation (1) does not hold, the process proceeds to step (2), where the manual mode is forced, the shutter speed and aperture value are read in step (2), and the process proceeds to display step (2).

In Fig. 2 (B), the same operations as in Fig. 2 (A) are performed from Steps ■ to ■, but in Fig. 2 (B), (
1) If the formula does not hold and you are in manual mode in step ■, read the shutter speed and aperture value in step ■ and proceed to step ■. If it is not the manual mode, the release is prohibited in step 10, the AE operation is terminated, and control is shifted to a control other than the AE operation.

According to the illustrated embodiment, even if it is possible to attach a shift lens or a tilt lens to a camera equipped with an automatic exposure control device, if the photometry sensor 12 is vignetted by the shift or tilt, the AE This operation can be prevented from being performed, thereby preventing photographing with incorrect exposure.

[Modification] Generally, in a shift lens or a tilt lens, the direction of shift or tilt can be changed freely, so the actual F-number converter 23 may be configured to output the actual F-number for each direction. In that case, the luminous flux can be used more effectively, and the possible range of AE operation can be expanded.

Further, even for lenses that can be shifted and tilted at the same time, it would be even more effective if the effective F-number is determined in a matrix from the respective amounts and directions.

The actual F-number converter 23 may be an arithmetic circuit that calculates the actual F-number from the amount of shift and tilt;
It may be a memory such as a ROM in which F numbers are stored in advance in correspondence with shift and tilt amounts.

Although the comparison circuit 25 is placed on the camera side, it may be placed on the objective lens side.

[Effects of the Invention] As explained above, according to the present invention, the effective F number of the objective lens is determined according to the direction and amount of parallel movement or inclination of at least a part of the optical axis of the objective lens. A real F number input terminal input from the side,
a limit F-number storage means for storing a minimum limit F-number necessary for normal AE operation; and before the AE operation, the actual F-number and the limit F-number are compared, and the former is larger than the latter. In some cases, a determination means for prohibiting the AE operation is provided, and by comparing the actual F-number and the limit F-number, the presence or absence of vignetting of the photometric sensor is detected and a determination is made as to whether to prohibit or permit the AE operation. Therefore, even when a shift lens or tilt lens is used as the objective lens, it is possible to prevent the mistake of taking a photograph with an incorrect exposure value due to an inadvertent AE operation. It becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 (
A), CB) are flowcharts of the embodiment in FIG. 1, and FIGS. 3 (A), (B), and (C) are diagrams explaining pupil vignetting in the case of a shift lens in the embodiment in FIG. 1,
FIG. 4 is a block diagram showing a conventional photometric optical system and an automatic exposure control device, and FIGS. 5(8) and 5(B) are diagrams illustrating the state of pupil vignetting in the case of a normal lens. DESCRIPTION OF SYMBOLS 1...Objective lens, 2...Focusing lens, 3...Aperture, 4...Aperture drive control circuit, 5...Memory for lens data, 6...Quick return mirror 7...Submirror , 8...Pentaprism,
9... Lens for photometry, 10... Sensor for photometry 11... Eyepiece, 12... Subject brightness calculation means, 13... Film sensitivity reading means, 14... AE
mote setting means, 15...exposure control means, 16...shutter 17.
...Shutter drive control circuit, 18...Exit pupil of normal lens, 19-1.19-2.19-3...Exit pupil of shift lens, 20-1.20-2.20-3. ...Circle indicating the actual F number, 21... Shift mechanism, 22... Shift encoder, 23... Actual F number converter, 24... Memory for limit F number, 25... Comparison circuit , tl~t4...Aperture data transmission connection terminal, t5...
Lens data output terminal, t6... Lens data input terminal, t7... Actual F number output terminal, t8... Actual F number input terminal. (B) (C)

Claims (1)

[Scope of Claims] 1. A camera equipped with an automatic exposure control device to which a shift lens or tilt lens can be attached, in which the amount of shift or tilt can be detected, wherein the shift lens is determined according to the amount of shift or tilt of the shift lens or tilt lens. , an actual F-number input terminal for inputting the actual F-number of the tail lens from the shift lens or tilt lens side, and a minimum F-number input terminal necessary for normal automatic exposure operation.
The apparatus further comprises a number storage means, and a determination means for comparing the actual F-number and the limit F-number before operating the automatic exposure means, and prohibiting the operation of the automatic exposure means when the former is larger than the latter. A camera with an automatic exposure control device featuring: 2. A camera with an automatic exposure control device according to claim 1, characterized in that the operation of the automatic exposure means is prohibited and the mode is forcibly switched to a manual mode. 3. The camera according to claim 1, characterized in that the method for prohibiting the operation of the automatic exposure means includes means for prohibiting the release operation when the metering mode is set to a mode other than manual. A camera with automatic exposure control.