JP2884691B2 - TTL automatic light control camera - Google Patents

Description

The present invention relates to a TTL automatic light control camera.

B. Prior Art FIG. 7 is a diagram showing a configuration of a conventionally known TTL automatic light control camera. The state at the time of viewfinder observation will be described. A light beam (stationary light) that has passed through the taking lens 2 of the single-lens reflex camera body 1 is reflected by the mirror 3 in the mirror-down state shown by the broken line, and passes through the screen 4 and the pentaprism 5 Then, a part is guided to the eyepiece 6, and the other part is guided to the exposure calculation photometric element 8 through the condenser lens 7. Also, the state during the shooting operation of the camera will be described, for example,
In the case of flash photography by backlight in fine weather,
Since the mirror 3 is retracted to the position indicated by the solid line, both the light emitted from the flash unit 9 and reflected by the subject and returned by the subject and the stationary light pass through the photographing lens 2 and pass through the shutter 10 which is opened. To reach the film surface 11. The light reflected by the film surface 11 passes through a condenser lens 12 and a light control photometric element 13
Is led to.

Here, the photometric output of the photometric element 8 for exposure calculation is used to determine the exposure value. Further, the photometric output of the photometric photometric element 13 is used to determine the emission stop time of the flash unit 9. That is, the light emission is stopped when the integrated value of the light control photometric output reaches a predetermined light amount.

In such a conventional TTL automatic light control camera, the amount of light emission is affected by the ratio of the main subject (for example, a person) on the screen and whether or not there is a high-reflectance object such as a mirror or a folding screen in the background. Dimming may not be performed properly. Therefore, as proposed in the specification of Japanese Patent Application No. 63-238976 by the present applicant, the light control photometric element 13 is divided into a plurality of areas to perform photometry, and preliminary light emission is performed before main light emission. By obtaining the reflectance distribution (luminance distribution) of the object scene from the photometric output from the photometric photometric element 13 and correcting the output of each photometric area by weighting according to the reflectance distribution, accurate photometric control is achieved. I do it.

C. Problems to be Solved by the Invention By the way, the light emission of the flash device 9 is usually performed by the light emission energy stored in the main capacitor, but the light emission energy stored by one charge has a limit as a matter of course. On the other hand, the main light emission requires more light quantity, that is, more light emission energy, as the sensitivity (ISO sensitivity) of the film loaded in the camera is lower. However, in the above-mentioned conventional TTL automatic light control camera, the flash is always pre-flashed and the weight correction is performed irrespective of the sensitivity of the film. When the sensitivity film is loaded, the light emission energy during the main light emission is insufficient due to the preliminary light emission, and proper light control may not be performed due to the insufficient light amount.

SUMMARY OF THE INVENTION An object of the present invention is to provide a TTL automatic light control camera that performs a proper light control even when a low-sensitivity film is loaded, while adopting a method of correcting a photometric output during light control according to a reflectance distribution of an object scene. Is to provide.

D. Means for Solving the Problems The present invention will be described with reference to FIG. 1 which is a diagram corresponding to claims. The present invention provides a main light emission for emitting a flash for photographing an object scene and a light emission before the main light emission. Flash means 9 capable of performing preliminary light emission to be performed; photometric means 13 for dividing the object field into a plurality of areas, measuring the reflected light from the plurality of areas by the flash means 9 and outputting respective photometric signals; Based on the photometric signal of the photometric means 13 obtained at the time of the preliminary flash, based on the photometric signal of the photometric means 13 obtained at the time of the main light emission, The light control means 102 for stopping the light emission of the flash means 9 in accordance with the photometric signal and the weight amount from the weight amount calculation means 101, and the sensitivity output means 105 for outputting the sensitivity of the loaded film.
Determining means 103 for determining whether the film sensitivity output from the sensitivity output means 105 is equal to or higher than a predetermined sensitivity, and determining means 1
When the film sensitivity is determined to be lower than the predetermined sensitivity by 03, the main light emission is performed without performing the preliminary light emission. Control means 10
4 to solve the above problem.

In the invention of claim 2, when the film sensitivity is determined to be lower than the predetermined sensitivity by the determination means 103, each photometric signal of the photometric means 13 is weighted by a predetermined weight. .

Further, according to a third aspect of the present invention, there is provided an exposure compensating means for compensating exposure information determined in advance in response to an external operation, and, when exposure compensation is performed by the exposure compensating means, a predetermined sensitivity is set in accordance with the compensation amount. And a sensitivity correcting means for correcting the temperature.

E. Operation The sensitivity output means 105 outputs the sensitivity of the loaded film, and the determination means 103 determines whether or not the film sensitivity output from the sensitivity output means 105 is equal to or higher than a predetermined sensitivity. The flash control means 104 performs main light emission without performing preliminary light emission when the determination means 103 determines that the film sensitivity is lower than the predetermined sensitivity. Therefore, when a low-sensitivity film that requires a large amount of light emission energy for the main light emission is loaded, the preliminary light emission is not performed, and the light emission energy during the main light emission does not run short.

In particular, in the second aspect of the present invention, when the determination means 103 determines that the film sensitivity is lower than the predetermined sensitivity, each photometric signal of the photometric means 13 is weighted by a predetermined weight.

According to the third aspect of the invention, when the exposure correction is performed, the predetermined sensitivity is corrected according to the correction amount.

F. Embodiment Hereinafter, an embodiment in which the present invention is applied to the single-lens reflex camera shown in FIG. 7 will be described with reference to FIGS.

FIG. 2 is a block diagram of a camera according to the present invention. The exposure calculation photometry element 8 is divided into five areas 8a to 8e, and the field of view is divided into five areas for photometry. The five outputs of the exposure calculation photometric element 8 are input to a microcomputer 21 having a CPU 21A, a D / A converter 21B, and the like, and used for a well-known exposure value calculation. Also, the photometric element 13 for dimming is 13a-1.
3e is divided into 5 areas, and the field of view is
Photometry is performed by dividing into areas. The scene divided by the five regions corresponds to the scene divided by the five regions of the exposure calculation photometric element 8. This light control photometric element 13-5
The two outputs are input to the weighted dimming circuit 40.

The microcomputer 21 receives a release signal from a release button 22, ISO information from an ISO information setting circuit 23, an open F-number signal from a lens memory 24, and exposure correction information from an exposure correction circuit 25. The ISO information is, for example, read from the DX code of the loaded film, and is information indicating the ISO sensitivity of the film. The exposure correction information is set in the exposure correction setting circuit 25 in accordance with the operation of an operation member (not shown), and the calculated exposure value is corrected based on this information.
In a camera of a type in which the user sets the ISO sensitivity with an operation member, the ISO information is set according to the operation of the operation member.

The microcomputer 21 calculates the aperture value and the shutter speed from the exposure value by a known method, and controls the shutter 27 and the aperture 28 via the exposure control circuit 26. Further, it is determined whether or not the flash photography is performed, and a flash start signal is input to the flash control circuit 29 at a predetermined timing during the flash photography. Further, the microcomputer 21 calculates a weighting amount Dn from the reflectance distribution of the object scene, as described later, converts the Dn into a voltage value En by the following equation (1), and inputs the voltage value En to the weighting dimming circuit 40.

En = K (1-Dn) Er (1) where n is 1 to 5 Er is a reference voltage K is a value corresponding to ISO information A weighted dimming circuit 40 is used for dimming as shown in FIG. Logarithmic compression circuits 41a to 41e that logarithmically compress and output the outputs from the respective areas 13a to 13e of the photometric element 13, and logarithmic compression circuits 41a
Integration circuits 42a to 42e for integrating the outputs of
Weighting correction circuits 43a to 43e for performing weighting processing on the outputs of the logarithmic compression circuits 41a to 41e, and a power supply voltage according to the five outputs of the weighted logarithmic compression circuits 41a to 41e.
A capacitor 44 for integrating the current flowing from Vcc, and a comparison between the voltage signal integrated by the capacitor 44 and the voltage signal of the reference power supply 45, and outputting a light emission stop signal when the voltage signal of the capacitor 44 exceeds the reference voltage signal. And a vessel 46.

The logarithmic compression circuits 41a to 41e are operational amplifiers OPe to OPe, respectively.
, Feedback diodes Da to De, and a reference voltage Er. Each of the weighting correction circuits 43a to 43e includes transistors Tra to Tre and variable power supplies VEa to VEe. The variable power supplies VEa to VEe output from the microcomputer 21 have a voltage value En ( n = 1 ~
5). The light emission stop signal of the comparator 46 is input to the flash control circuit 29 to stop the light emission of the flash device 9.

The operation of the thus configured TTL automatic light control camera will be described with reference to the flowcharts of FIGS.

In FIG. 4, when the release button 22 is turned on, a step is performed.
Proceeding to S1, the luminance values BVn (n = 1 to 5) of the five photometric outputs from the exposure calculating photometric element 8 are read, and proceeding to step S2, the use / non-use of the flash unit 9 is determined. . If it is used, the process proceeds to step S3. If it is not used, the process proceeds to step S10.

In step S3, the brightness value BVn is processed by a predetermined algorithm to determine the exposure value BV (see, for example, FIG. 5 of JP-A-63-83713). In step S4, the ISO information SV and the exposure correction information ΔEV are read and the
Proceeding to 5, the aperture value AV and the shutter speed TV are determined based on the exposure value BV, the ISO information SV, and the exposure correction information ΔEV. That is, when the exposure compensation operation is performed (Δ
In EV ≠ 0), the exposure value BV is corrected based on the exposure correction information ΔEV, and the aperture value AV is calculated based on the corrected exposure value BV and the ISO information SV.
And determine the shutter speed TV. If the exposure correction operation has not been performed, AV and TV are determined from the exposure value BV obtained in step S3 and the ISO information SV.

Next, at step S6, whether the exposure correction has been performed is determined from .DELTA.EV, step S8 performs the correction of the predetermined ISO sensitivity value SV _x in step S7 it is determined that the exposure correction has been performed if .DELTA.EV ≠ 0 Proceed to. That is, a predetermined IS
And O sensitivity value SV _x exposure compensation value .DELTA.EV a new predetermined ISO sensitivity value SV _x plus _{(SV x = SV x + ΔEV} ). Also when it is determined that .DELTA.EV = 0 in step S6, the exposure compensation proceeds directly to step S8 without correction of it it is determined that not performed predetermined ISO sensitivity value SV _x.

In step S8, the ISO information SV is set to a predetermined ISO sensitivity value SV _x
It is determined whether or not smaller than (SV <SV _x or not), and SV <SV _x
When to step S21 of FIG. 5, when the SV ≧ SV _x processing proceeds to step S31 in FIG. 6. Here, SV _x is, for example, SV _x = 3 (ISO25) when the exposure compensation is not performed, and
If the preliminary light emission is performed when the information SV is lower than this, the light amount at the time of the main light emission will be insufficient, and the value will be set so that accurate light control cannot be performed. Therefore, in the procedure after step S21, shooting is performed by setting a predetermined center-weighted amount before performing main emission without performing preliminary emission.

FIG. 5 shows the procedure after step S21.
At 21, the aperture value is reduced to the determined aperture value AV and the mirror is raised, and the process proceeds to step S22 without performing the preliminary light emission.
To set the weighting amount Dn. In this embodiment, securing the weighting amount Dn in a low speed film preloaded central focus, the central D ₁ = 2/6 peripheral _{D 2 ~ 5 = 1/6} . Next, in step S23, the voltage value En corresponding to the weighting amount Dn is obtained by the above equation (1), and the microcomputer 21 sets the variable power supplies VEa to VEe of the weighting dimming circuit 40 to those values. Next, in step S24, the microcomputer 21 inputs a light emission start signal to the flash control circuit 29 to start main light emission, and drives the shutter 27 at a predetermined timing. Then, dimming is performed in step S25.

 The light control in this embodiment is performed as follows.

Outputs of the respective regions 13a to 13e of the light control photometric element 13 are amplified by logarithmic compression circuits 41a to 41e and input to bases of transistors Tra to Tre constituting weight correction circuits 43a to 43e. As a result, the transistors Tra to Tre are turned on and the power supply voltage Vc
A collector current flows from c through the capacitor 44. The variable power supplies VEa to VEe connected to the emitters of the transistors Tra to Tre are set to a voltage value En weighted with a central emphasis, and the collector current increases as the voltage value En decreases.

Therefore, in this case, the capacitor 44 is charged depending on the photometric output of the central region 13a rather than the peripheral region of the light control element 13. When the potential of the capacitor 44 exceeds the reference potential, the comparator
A flash stop signal is input from 46 to the flash control circuit 29, and flashing is stopped.

If it is determined that SV ≧ SV _x in step S8 in FIG. 4, i.e., the ISO information SV is equal to or higher than a predetermined ISO sensitivity value SV _x 6
The process proceeds to step S31 in the figure. The procedure after step S31 is to perform preliminary light emission, estimate the reflectance distribution of the object field from the reflected light, determine the weight of the output of the light control photometric element 13, and perform light control.

In step S31, the mirror 3 is raised and the diaphragm 28 is stopped down. Then, in step S32, the microcomputer 21 outputs a preliminary light emission signal to the flash control circuit 29 to perform preliminary light emission. The reflected light from the subject accompanying the preliminary light emission passes through the photographing lens 2, is reflected by the shutter curtain surface 10, passes through the condenser lens 12, and reaches the light control photometric element 13. As described above, the element surface of the light adjusting photometric element 13 is 13a to 13e.
The subject field is divided into five regions and photometry is performed. The photometric output according to the amount of light reflected from the subject is integrated by integrating circuits 42a to 42e, and in step S33 each integrated signal is taken into the microcomputer 21, and in the next step S34, the reflectance distribution Rn is expressed by the following equation. Is calculated.

In steps S35 to S41, the reflectance distribution Rn (n =
A photometry area (Rn> 0.8) with very high 1-5) and a photometry area with very low (Rn <0.1) are extracted and cut. The existence of a photometric region with a very high Rn means that, for example, a gold screen, a white wall, or the like is behind the main subject (person). Also, the existence of a photometric region having a very low Rn means that, for example, the background of the main subject (person) has been lost due to a scenery-like background. In any case, these are factors that have an adverse effect on TTL dimming. That is, the reflectance distribution Rn (n = 1 to 5) of the region to be cut is set to 0.
In order not to contribute to subsequent calculations.

When the high-luminance or low-luminance cut is completed for the entire area of the light control photometric element 13, the process proceeds to step S42, and the weighting amount Dn is calculated using the reflectance distribution Rn (n = 1 to 5) after the cut processing. Ask by Then, in step S43, (1)
The weighting amount Dn is converted into a voltage value En based on the equation and input to the weighting dimming circuit 40.

Then, in step S44, the microcomputer 21
An emission start signal is output to the flash control circuit 29 to make the flash unit 9 emit main light. At this time, the main mirror 3 is mirrored up, and the aperture 28 of the lens is also reduced to the photographing aperture value, and the reflected light from the subject of the main emission passes through the lens 2 and is reflected by the film surface. The light reaches the light control photometric element 13, and the reflected light of the main light emission from the subject is divided into five regions to perform photometry. The photometric output from the photometric
At the timing of S45, the weighting is performed by the weighting dimming circuit 40 and integrated by the capacitor 44. Then, the light emission stop signal is input from the comparator 46 to the flash control circuit 29 when the integrated amount of the five regions exceeds the reference value, and light emission is stopped.

Therefore, when the reflectance of the central region 13a is higher than that of the other peripheral regions, the photometric output of the peripheral region contributes to the detection of the light emission amount more than the photometric output of the central region, and the reflectance distribution Rn of the central region 13a has a predetermined value. If the value is higher or lower than the value, the photometric output in that area does not contribute to the light emission amount detection. As a result, appropriate dimming is possible even when the subject has a very high reflectance.

On the other hand, if it is determined in step S2 of FIG. 4 that the flash device 9 is not used, in step S10, the exposure value BV is determined by the normal photographing algorithm using the luminance value BVn.
Then, in step S11, the ISO information SV and the exposure correction information ΔEV are read, and based on these, the shutter speed TV and the aperture value AV are determined in step S12. After that, the mirror is raised and the aperture 28 is stopped down in step S13, and photographing is performed in step S14.

In the configuration of the above embodiment, the flash unit 9 is a flash unit, the dimming photometric element 13 is a photometric unit, the microcomputer 21 is a weighting amount calculating unit, the capacitor 44 of the weighted dimming circuit 40, the reference power supply 45 and The comparator 46 constitutes light control means, the ISO information setting circuit 23 constitutes sensitivity output means, the microcomputer 21 constitutes determination means, and the microcomputer 21 and the flash control circuit 29 constitute flash control means. The exposure compensation setting circuit 25 constitutes an exposure compensation unit, and the microcomputer 21 constitutes a sensitivity compensation unit.

In the above description, the weighting amount is calculated for each area of the light control photometric element 13 to correct the photometric output of each area. However, it is not always necessary to perform the weighting correction for each area, and some May be grouped, and the weight may be calculated and corrected for each group. In any case, any correction method may be used as long as the correction is performed in accordance with the reflectance distribution of the object scene.

Also, an example has been described in which preliminary light emission is performed to obtain a weighting amount. However, this preliminary light emission may be used, for example, for subject distance detection for determining the aperture diameter of a diaphragm at the time of main light emission.

G. Effects of the Invention According to the present invention, when the sensitivity of the loaded film is lower than the predetermined sensitivity, the main light emission is performed without performing the preliminary light emission. Even when a low-sensitivity film is loaded, the amount of light at the time of main light emission does not become insufficient, and proper light control can be performed. On the other hand, when the sensitivity of the film is equal to or higher than the predetermined sensitivity, preliminary light emission is performed. Therefore, appropriate light control can be performed based on the preliminary light emission as in the related art.

In particular, according to the second aspect of the invention, when the low-sensitivity film is loaded, the photometric output is corrected in accordance with a predetermined reflectance distribution, so that more appropriate light control can be performed.

According to the third aspect of the invention, when the exposure correction is performed, the predetermined sensitivity is corrected according to the correction amount. Therefore, even when the exposure correction is performed, regardless of the correction amount. The determination as to whether or not to perform the preliminary light emission is appropriately performed, and it is possible to reliably prevent the light amount shortage when the low-sensitivity film is loaded.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims. 2 to 6 illustrate an embodiment of the present invention.
FIG. 2 is a block diagram showing the overall configuration, FIG. 3 is a detailed diagram of a weighted dimming circuit, and FIGS. 4 to 6 are flowcharts showing examples of processing procedures. FIG. 7 is a sectional view of a TTL automatic light control camera. 9: Flash device, 13: Photometric element for dimming 13a to 13e: Photometric area 21: Microcomputer, 21A: CPU 23: ISO information setting circuit 25: Exposure compensation setting circuit, 29: Flash control circuit 40: Weighted dimming circuit 42a to 42e: integration circuit 43a to 43e: weight correction circuit 44: capacitor, 45: reference voltage 46: comparator, 101: weight calculation means 102: dimming means, 103: determination means 104: flash control means, 105: sensitivity Output means

Claims (3)

(57) [Claims] 1. A flash unit capable of performing main light emission for emitting light for flash photography of an object field and preliminary light emission for emitting light before the main light emission, and dividing the object field into a plurality of regions. A metering means for metering each reflected light from the plurality of areas by the flashing means to output respective metering signals; and obtaining the light metering signal based on the metering signal of the metering means obtained at the time of the preliminary flash. Weighting means for calculating a weighting amount for correcting the photometric signal of the photometric means, and the flash means according to the photometric signal from the photometric means and the weighting amount from the weighting amount calculating means during the main light emission. Dimming means for stopping the light emission of the above, sensitivity output means for outputting the sensitivity of the loaded film, determination means for determining whether or not the film sensitivity output from the sensitivity output means is equal to or higher than a predetermined sensitivity; By means When the film sensitivity is determined to be lower than the predetermined sensitivity, the main light emission is performed without performing the preliminary light emission, and when the film sensitivity is determined to be equal to or higher than the predetermined sensitivity by the determination unit, the main light emission is performed. A TTL automatic light control camera, comprising: a flash control means for performing the main light emission. 2. A camera according to claim 1, wherein when the determination means determines that the film sensitivity is lower than the predetermined sensitivity, each photometric signal of the photometric means is weighted by a predetermined weight. TTL automatic light control camera characterized by performing. 3. An exposure compensating means for compensating exposure information determined in advance in accordance with an external operation, and when the exposure compensation is performed by the exposure compensating means, the predetermined sensitivity is adjusted in accordance with the compensation amount. 2. The apparatus according to claim 1, further comprising: a sensitivity correction unit configured to perform correction.
Or the TTL automatic light control camera described in 2.