JP3260173B2 - Exposure control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure control apparatus which uses a flash of a camera, and more particularly to an exposure control apparatus which can set a minimum aperture value according to film sensitivity and shooting distance.

[0002]

2. Description of the Related Art In a program exposure mode, there is an exposure control device having a program shift function capable of changing a combination of a shutter speed and an aperture value while maintaining the same exposure value. In this program shift, a predetermined shift amount shift is added to or subtracted from each value after obtaining the shutter speed Tv and the aperture value Av based on the exposure value Ev . For example, the formula, Ev = (Av + shift) +
(Tv-shift) realizes a program shift.

However, when a strobe is used, there is a limitation on a high-speed shutter side, ie, a flash tuning speed, and a limitation on a low-speed shutter side, ie, a camera shake limit shutter speed for preventing camera shake. Therefore, the program exposure mode in which the relationship between the shutter speed and the aperture value is programmed in advance and the shutter speed and the aperture value are uniquely set within the range of the above-mentioned limit values based on the brightness (exposure value) of the subject is a flash exposure mode. Sometimes, the settable range of the shutter speed and the aperture value is narrow, and the exposure value range in which the shutter speed and the aperture value change in conjunction is narrow.

[0004] Further, the conventional flash program, when using a high-sensitivity film, narrows the aperture by the number of steps corresponding to the increase in the film sensitivity, and enables flash photography with an appropriate exposure value within a fixed distance range regardless of the film sensitivity. The aperture was controlled so that it would be. Therefore, even if a high-sensitivity film is used, the photographing distance at which proper flash photography can be performed does not increase. On the other hand, if you shoot an object at a short distance with flash, the amount of flash reflected by the object is large,
In the light emission stop control by TTL direct photometry, the stop of strobe light emission is delayed and the exposure tends to be over.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an exposure control apparatus which enables proper flash photography without overexposure even at a short distance while using a high-sensitivity film to increase the proper flash photography distance at the time of flash photography. The purpose is to do.

[0006]

SUMMARY OF THE INVENTION To achieve this object, the present invention provides a photometric device.
If the film sensitivity setting unit, a photographing distance detecting means, and calculating means for calculating a shutter speed and the aperture value based on the film speed set by the photometric value and the film speed setting means of the metering means, the exposure control use
Exposure control means for setting a shutter speed and an aperture value ;
The provided, said calculating means, the <br/> when you shoot Turning the Flash, the first minimum limit aperture value on the open side, film sensitivity by weighting of greater than 1 than 0 to the film speed as well as calculated by the first formula is narrowed high indeed stop, the second minimum limit diaphragm value of the open side, is calculated by a second equation object distance which the photographing distance detection unit detects are narrowed down closer , Dew above
Output control means for setting a smaller one of the first and second minimum limit aperture values calculated by the calculation means as an open-side minimum limit aperture value used in exposure control ; Has features. The weight is 1 /
A 2 definition, when the first minimum limit aperture value APEX value AvMINLMT, the first equation by AvMINLMT = (5-AvMIN) / 2 + (Sv-5) / 2 + AvMIN = Sv / 2 + AvMIN / 2 Assuming that the second minimum limit aperture value is the apex value AvMINLMT2, the second equation is defined as: AvMINLMT2 = 5-Dv + (Sv-3) / 2 = Sv / 2-Dv + 7/2. Exposure control device. Here, AvMIN: Apex value of the open aperture of the photographing lens Sv: Apex value of the set film sensitivity Dv: log {shooting distance (m)} ² / log2

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on illustrated embodiments. FIG. 1 is a block diagram of a main part of a single-lens reflex camera equipped with a flash exposure control device of the present invention. The camera body 1 has a zoom lens 2 mounted thereon, and an externally mounted strobe 3 mounted thereon. The camera body 1 has a main CPU 4, the zoom lens 2 has a lens CPU 5,
The external flash 3 includes a flash CPU 6. The main CPU 4 is connected to the lens CPU 5 and the flash CPU 6 via buses 7 and 8 connected via connectors (not shown). A predetermined data transfer is performed.

Although not shown in detail, the camera body 1 has a main switch for turning on / off the power, a photometry switch, a release switch, an ISO sensitivity setting, a manual, a program, a shutter priority, and an aperture priority, which are collectively denoted by reference numeral 11. A switch for selecting a camera function for selecting an exposure mode and a strobe light emission mode from among them, and an up switch 11U and a down switch 11D for performing a program shift operation are provided. Checked by CPU4.

The camera body 1 further includes a photometric circuit 12 for measuring the brightness of the subject, a flash dimming circuit 13 for controlling the stop of the flash by performing TTL direct metering of the subject light after the start of the exposure (after the flash emission), And a DX code reading circuit 14 for reading a DX code relating to the ISO sensitivity of the film. These output signals are input to the CPU 4. In the camera body 1, a shutter / aperture control circuit 1 is provided as an exposure control system.
The main CPU 4 drives and controls the shutter 16 and the aperture 21 of the zoom lens 2 via the shutter / aperture control circuit 15.

The zoom lens 2 has a zoom code plate 22 for detecting a current focal length and a distance code plate 23 for detecting a photographing distance ( subject distance) at which a focus lens (not shown) is focused. The lens CPU 5 reads the current focal length data and the current shooting distance data via these code plates 22 and 23. In addition,
The ROM of the lens CPU 5 stores lens information such as maximum aperture value Av and minimum aperture value Av (open F number) data of the zoom lens 2.

The ROM of the strobe CPU 6 stores various data required for strobe light control, such as a guide number and an irradiation angle. The strobe CPU 6 outputs strobe data such as a guide number to the main CPU 4 and inputs signals such as strobe light emission preparation, light emission, and light emission stop from the main CPU 4.

This single-lens reflex camera has a flash program and a program shift function that function in flash light emission (flash light emission mode) in addition to a normal photographing function. The strobe program of the present invention assigns a weight of 0 to less than 1 to the film speed Sv, that is, reduces the amount of narrowing down when a high-speed film is used. However, proper exposure is possible. On the other hand, in the case of a subject at a short distance, by narrowing down according to the shooting distance, it is possible to perform flash photography with an appropriate exposure value even at a short distance. Furthermore, with this single-lens reflex camera, program shift is enabled even in flash photography,
The setting range of the shutter speed Tv and the aperture value Av is widened.

The main photographing operation of this single-lens reflex camera will be described with reference to the flow charts shown in FIGS.
This will be described with reference to the program diagram shown in FIG. This photographing operation is totally controlled by the main CPU by a program stored in the ROM of the main CPU 4.
The definitions and contents of main abbreviations used in the description of this flowchart are described below. Note that these values are all apex values.

Lv: Exposure value (exposure value Ev with predetermined correction) AvMIN: Minimum aperture value ｛Zoom lens 2
Open aperture (open F value)｝ AvMAX: maximum aperture value 最小 minimum aperture (maximum F value) of zoom lens 2｝ TvMIN: minimum shutter speed (lowest shutter speed that camera body 1 can control) TvMAX: maximum shutter speed (The fastest shutter speed that can be controlled by the camera body 1; however, for flash photography, the flash synchronization limit speed) AvMINLMT
: Minimum limit aperture value (first minimum limit aperture value)
(Aperture limit and fixed aperture for flash photography) AvMINLMT2: Second minimum limit aperture (open aperture limit for short-distance flash photography) AvMAXLMT : Maximum limit aperture (aperture aperture for flash photography) Limit value) TvMINLMT: Minimum limit shutter speed (limit value on the low-speed shutter side during flash photography) fv:
Focal length (apex-converted value of focal length f (mm) of zoom lens 2) fv = logf / log2Dv: shooting distance (apex-converted value of shooting distance D (m)) Dv =
logD ² / log2Tvf: shake limit shutter speed (a value according to the focal length f of the zoom lens 2) Tvf =
(3/4) × fv + 2

"CPU MAIN processing" The CPU MAIN flow, which is the main flowchart of the camera, is as follows.
5 is a simplified flowchart for explaining an outline of main operations of the camera. The CPU MAIN process is started when the main switch is turned on. In this process,
First, initialization processing (S101 to S105) of the RAM relating to the initialization, photographing processing, and automatic focusing (AF) processing of each port of the CPU 4 is executed.
The following intermittent processing by the 00 ms timer and the 4 ms timer is repeated.

First, an up / down switch 11U, 1
The ON / OFF state of each switch including 1D is input, and a process (only a program shift process is shown) corresponding to the turned on switch is executed (S107). Here, if the up / down switches 11U and 11D are turned on, the program shift up / down processing of FIGS. 4 and 5 is executed on condition that the program exposure mode or the strobe program exposure mode is set.

If none of the switches are turned on,
When the predetermined process corresponding to the switch that has been turned on is completed, although not shown in detail, a process related to a known automatic focus adjustment is executed to move the focus lens group of the zoom lens 2 to a focus position (S109). And check if the 4ms timer has expired,
If the time is up, check the state of the release switch. If it is on, release processing (not shown)
If it is not turned on, the process returns to S107 (S111, S11
9).

When the 4 ms timer has not expired, it is checked whether the 100 ms timer has expired.
It returns to 101 (S111, S113). When the 100 ms timer has expired, predetermined lens data and strobe data are input from the lens CPU 5 and the strobe CPU 6, respectively (S115). Then, a predetermined process related to exposure is executed by calling the photometry / calculation subroutine of FIG. 3, and the process returns to S107 (S11)
7, S107).

[Photometry / Calculation Processing] The photometry / calculation processing called in step S117 will be described with reference to the flowchart shown in FIG. In this processing, first, the luminance of the subject is measured, and the photometric data is set at a predetermined address.
The data relating to the AE operation is cleared and an initial value is set (S201, S203). Further, the photographing distance D input from the lens CPU 5 is converted into a photographing distance value Dv, data necessary for exposure processing such as a minimum aperture value AvMIN and a maximum aperture value AvMAX are set, and an exposure value Lv is calculated (S2).
05, S207, S209).

When the strobe is not fired, the process branches depending on whether or not the strobe is fired. When the strobe is not fired, a subroutine (not shown) corresponding to the selected exposure mode is called to perform exposure control. The shutter speed Tv and the aperture value Av are calculated and set (S21).
1, S223 to S229). To make the flash fire, set the flash tuning speed to the maximum shutter speed TvMAX, and then call the exposure subroutine corresponding to the selected exposure mode to set the shutter speed Tv for exposure control.
And the aperture value Av are calculated and set (S211 and S2).
13 to S221). Here, when the program exposure mode is selected, the flash program processing subroutine shown in FIG. 6 is called (S215, S21).
9). When returning from the exposure subroutine, data such as the shutter speed Tv and the aperture value Av calculated in each exposure subroutine are set, and the process returns to the main routine.

"Program shift up / down processing"
FIGS. 4 and 5 are flowcharts relating to program shift up / down processing for setting a program shift. The program shift of this embodiment is set based on the shift amount with respect to the shutter speed Tv. That is,
The plus one step program shift means the shutter speed T
v is added by 1 Tv (shifted in the plus (positive) direction), and the program shift of minus one step means the shutter speed Tv
Is subtracted by 1 Tv (shifted in the minus (negative) direction). In the present embodiment, the shift value is subjected to absolute value processing, the magnitude thereof is represented by a program (P) shift amount, and positive or negative is identified by a P shift direction bit.

In the switch data reading process of S107, if the up switch 11U is on, P
(Program) The shift-up process is started, and if the down switch 11D is turned on, the shift-down process is started.

In the P shift up process, the program (P) shift amount after S305 is increased on condition that the control shutter speed Tv is lower than the maximum shutter speed TvMAX and the control aperture value Av is larger than the minimum aperture value AvMIN. If the program shift amount is increased when the above condition is not satisfied, the shutter speed Tv becomes uncontrollable.
Alternatively, since the aperture value becomes Av, the process returns without increasing (S301, S303, S305).

In step S305, the current program shift direction is checked by the P shift direction bit. If it is positive ("0"), the P shift amount becomes the maximum value 15 4/8 (Tv
) Or more until it becomes greater than 0.5Tv, and returns (S305-S309). If negative ("1"), P is added.
The shift amount is subtracted in units of 0.5 Tv and the process returns. When the P shift amount becomes 0, the positive value of the P shift direction bit: “0”
And returns (S305, S311 to S3)
15).

In the P shift down process, the program (P) shift amount shift down from S355 is performed on condition that the calculated shutter speed Tv is larger than the minimum shutter speed TvMIN and the calculated aperture value Av is smaller than the maximum aperture value AvMAX. If the program shift amount is reduced when the above conditions are not satisfied, the shutter speed Tv becomes uncontrollable.
Alternatively, since the aperture value becomes Av, the process returns without going down (S351, S353, S355).

In S355, the current program shift direction is checked by the P shift direction bit, and if it is negative ("1"), it is added in units of 0.5 Tv until the P shift amount reaches the maximum value of 15 4/8 or more. And return (S3
55, S363, S365), if it is positive (“0”), P
The shift amount is subtracted in units of 0.5 Tv. If the P shift amount becomes 0 or less, the P shift amount is subjected to absolute value processing, the P shift direction flag bit is set to negative: "1", and the process returns (S
355, S357-S361). The program shift amount and the program shift direction bit set in the above processing are used in the flash program shift processing of FIG. Note that the magnitude of the program shift amount that can be changed by one operation is not limited to 0.5 Tv.

"Strobe program exposure calculation processing" FIG. 6
5 is a flowchart relating to a flash program process called in S219 of the photometry / arithmetic subroutine of FIG. The flash program according to the present embodiment has a minimum limit shutter speed TvMINLM according to the focal length of the taking lens.
T and set the maximum limit aperture value AvMAXLMT and the minimum limit aperture value AvMIN according to the film speed Sv.
LMT is set, and the minimum limit aperture value AvMINLMT is changed according to the shooting distance. Shutter speed Tv and aperture value Av
Is the maximum limit aperture value AvMAXLMT, the minimum limit aperture value AvMINLMT, and the minimum limit shutter speed TvM
It is determined by INLMT and the maximum shutter speed TvMAX (strobe tuning limit speed). Further, when the program shift is executed, the interlocking range of the maximum aperture value AvMAX, the minimum aperture value AvMIN, the minimum shutter speed TvMIN, and the maximum shutter speed TvMAX of the photographing lens is expanded.

FIG. 12 is a program diagram of the present embodiment obtained by the flash program processing of FIG. In the figure, an exposure value E determined by a minimum limit aperture value AvMINLMT and a minimum limit shutter speed TvMINLMT.
v1 is the lower limit exposure value and the minimum limit aperture value AvMINLMT
And the maximum shutter speed TvMAX is the second exposure value Ev2.
The exposure value Ev3 determined by the maximum shutter speed TvMAX and the maximum limit aperture value AvMAXLMT is the upper limit exposure value.

In this process, first, the film sensitivity S
Corrected film speed SX obtained by subtracting the exposure correction value Xv from v
v is obtained (S401). Then, the correction film sensitivity SXv is set to 3 (equivalent to ISO 25 ) or more and
(Corresponding to 0) or less (S403 to S40)
9). This is because the correction film sensitivity SXv is ISO400
When it is larger than the equivalent value, the maximum limit aperture value AvMAXLMT (= SXv + 2) set in S411 becomes too large and exceeds the practical range (controllable range) . On the other hand, when the correction film sensitivity SXv is smaller than ISO25 equivalent, it becomes practical. This is because it is smaller than the range (controllable range).

Next, the processed corrected film sensitivity S
Based on Xv, the maximum limit aperture value AvMAXLMT is obtained from the equation AvMAXLMT = SXv + 2 (S411). Then, the maximum limit aperture value AvMAXLMT is set to the minimum aperture value AvMIN
The minimum aperture value AvMIN is controllable if it is less than the minimum aperture value AvMIN.
Is set to the maximum limit aperture value AvMAXLMT (S41).
3, S415). Furthermore, the maximum limit aperture value AvMAXLM
It is determined whether T is equal to or smaller than the maximum aperture value AvMAX. If T is equal to or smaller than the maximum aperture value AvMAXLMT, the controllable maximum aperture value AvMAX is set to the maximum limit aperture value AvMAXLMT (S417, S419).

Then, a minimum limit aperture value AvMINLMT for flash photography is obtained by the following equation (S42).
1). AvMINLMT = (5-AvMIN) / 2 + (Sv-5)
/ 2 + AvMIN ... This equation gives 0 to the film speed Sv.
By weighting less than 1 (1/2) as described above, even if the film sensitivity Sv becomes high, the amount of narrowing down according to the film sensitivity Sv is reduced, and a further distant subject can be properly exposed. is there. For example, zoom lens 2
Is F4 (AvMIN = 4), when the film is ISO 100 (Sv = 5), AvMINLMT = 4 1
/ 2, and when the film sensitivity is ISO400 (Sv = 7), AvMINLMT = 51/2. In addition, (5-AvMIN) / 2 + (Sv-5) / 2 in the formula is usually 0 or more. Here, the minimum limit aperture value AvMINLMT may be smaller than the minimum aperture value AvMIN. Therefore, it is checked whether the minimum limit aperture value AvMINLMT is less than the minimum aperture value AvMIN. If the minimum aperture value is less than the minimum aperture value AvMIN, the minimum aperture value AvMIN is set to the minimum limit aperture value AvMINLMT.
(S423, S425).

Next, when the subject is a short distance, the minimum limit aperture value AvMINLMT is changed according to the photographing distance Dv, that is, in order to enable proper strobe photography even for a short distance subject. Second minimum aperture value A
vMINLMT2 is calculated by the following equation (S427). AvMINLMT2 = 5-Dv + (Sv -3) / 2 ... This expression, for a nearby subject, the weighting of 0 or more and less than 1 in film sensitivity Sv (1/2), and Ta
The feature is that the aperture is narrowed down according to the shadow distance Dv.

[0033] Then, the second minimum limit diaphragm value AvMINLMT2 according to the shooting distance and the minimum limit diaphragm value AvMIN
The larger value compared to LMT is used as the fixed aperture value. For example, if the second minimum limit aperture value AvMINLMT2 is larger, the second minimum limit aperture value AvMINLMT2 is set to the minimum limit aperture value AvMINLMT (S429, S429).
S431). That is, the second minimum limit aperture value AvMIN
If LMT2 is larger, the normal photographing distance is very short, so the second minimum limit aperture value AvMINLMT2, which increases as the photographing distance decreases, is set to the minimum limit aperture value A.
vMINLMT. For example, when the open aperture value of the zoom lens 2 is F4 (AvMIN = 4) and the film is ISO10
In the case of 0 (Sv = 5), the shooting distance D is 1 m (Dv = 0).
AvMINLMT2 = 6 at the time of
(= 4 1/2), so in this case AvMINLM
T2 = 6 is set to the minimum limit aperture value AvMINLMT,
The aperture is reduced by two steps from the open aperture.

Further, the minimum limit aperture value AvMINLMT is compared with the maximum limit aperture value AvMAXLMT, and the minimum limit aperture value AvMINLMT is larger than the maximum limit aperture value AvMAXLMT.
If it is larger than T, the maximum limit aperture value AvMAXLMT is set to the minimum limit aperture value AvMINLMT (S435).

After obtaining the limit aperture values AvMINLMT and AvMAXLMT, the control shutter speed Tv is obtained. First, a value obtained by subtracting 0.5 Tv from the camera shake limit shutter speed Tvf is set to the minimum limit shutter speed TvMINLMT (S
437). Then, the minimum aperture value A is set to the aperture value Av.
vMINLMT is set and Tv calculation subroutine (Fig. 10)
To calculate the shutter speed Tv based on the aperture value Av (S439, S441).

The control shutter speed Tv is set to a minimum limit shutter speed TvMINLMT and a maximum shutter speed TvMAX.
(S443 to S449) A limit process is performed to fall within the range of (tuning shutter speed Tv). That is, if the control shutter speed Tv is lower than the minimum limit shutter speed TvMINLMT, the minimum limit shutter speed TvMINLMT is set to the control shutter speed Tv (S443, S447). If the control shutter speed Tv is higher than the maximum shutter speed TvMAX, the maximum is set. Set the shutter speed TvMAX to the control shutter speed Tv, and set the proper shutter speed Tv
Is set to "1" in the Tv over flag for identifying a larger value (S443, S445, S44
9).

Next, an Av calculation subroutine (FIG. 11) is called to obtain a control aperture value Av based on the control shutter speed Tv, and the control aperture value Av is set to a maximum limit aperture value AvMAXLMT and a minimum limit aperture value AvMINLMT. Is performed (S453-S459).
That is, the control aperture value Av is equal to the maximum limit aperture value AvMAXLM
When it is larger than T , the maximum limit aperture value AvMAXLMT
Is set to the control aperture value Av (S453, S455),
If the control aperture value Av is smaller than the minimum limit aperture value AvMINLMT, the minimum limit aperture value AvMINLMT is set to the control aperture value Av.
(S457, S459).

When the setting of the control shutter speed Tv and the control aperture value Av is completed, the flash program shift subroutine (FIG. 9) is called, the control shutter speed Tv and the control aperture value Av are shifted, and the process returns (FIG. 9). S461).

[Tv, Av calculation processing] Tv, Av calculation processing for performing Tv, Av value limit processing is shown in FIG.
0, and will be described with reference to the flowchart shown in FIG. In the Tv calculation process, first, “0” is set to the Tv under flag and the Tv over flag, and the exposure value Lv
And the appropriate control shutter speed Tv from the control aperture value Av
(S601, S603). Then, it is checked whether the appropriate control shutter speed Tv is between the minimum shutter speed TvMIN and the maximum shutter speed TvMAX,
If it is during this period, the process returns (S605, S607).

Here, when the proper control shutter speed Tv is smaller than the minimum shutter speed TvMIN, the minimum shutter speed TvMIN is set to the control shutter speed Tv, and T is used to identify that the proper shutter speed is smaller than this value TvMIN.
v Set "1" to the under flag and return (S605, S609). When the proper control shutter speed Tv is higher than the maximum shutter speed TvMAX, the maximum shutter speed TvMAX is included in the control shutter speed Tv, and the Tv over flag for identifying that the proper shutter speed is higher than this value TvMAX is set to “1”. Then, the process returns (S605, S607, S611).

In the Av operation process, similarly to the Tv operation process, first, the Av under flag and the Av over flag are set to "0", and an appropriate control aperture value Av is obtained from the exposure value Lv and the control shutter speed Tv (S651, S
653). Then, it is checked whether or not the proper control aperture value Av is between the minimum aperture value AvMIN and the maximum aperture value AvMAX, and if it is between them, the process returns (S655, S655).
657).

Here, when the proper control aperture value Av is smaller than the minimum aperture value AvMIN, the minimum aperture value AvMIN is set in the control aperture value Av, and an Av under flag for identifying that the appropriate aperture value is smaller than this value AvMIN. Is set to "1" and the process returns (S655, S659). When the appropriate control aperture value Av is larger than the maximum aperture value AvMAX,
The maximum aperture value AvMAX is set in the control aperture value Av, and the Av over flag for identifying that the appropriate aperture value is larger than this value AvMAX is set to "1", and the routine returns (S65).
5, S657, S661).

With the above processing, the control shutter speed Tv
And the control aperture value Av is set to a value that can be actually controlled by the camera body 1 and the zoom lens 2.

"Strobe P shift process" Next, the strobe program (P) shift of the present invention will be described with reference to FIG.
12 and the program diagram shown in FIG. The strobe P shift of the present invention is characterized in that the shift is performed within a wide range indicated by a broken line in the program diagram of FIG. This flowchart is based on step S of the flash program subroutine.
Called at 461.

In this flowchart, it is checked whether or not the program shift amount is 0. If the program shift amount is 0, the program shift is not performed and the routine returns. If not, the following shift processing is executed (S501). First, the exposure value Lv obtained by the photometry and calculation processing of FIG. 3 is set in the Lv memory, and the sum of the control shutter speed Tv and the control aperture value Av obtained by the flash program processing is set in the exposure value Lv (S503, S505). By this processing, when the exposure value Lv obtained by the photometry and calculation processing is smaller than the lower limit exposure value Ev1, the combination of the control shutter speed Tv and the control aperture value Av can be shifted along the lower limit exposure value Ev1 line. When the exposure value Lv is equal to or larger than the lower limit exposure value Ev1 and equal to or smaller than the upper limit exposure value Ev3, the control shutter speed Tv and the control aperture value Av are adjusted along the exposure value Ev line corresponding to the subject brightness.
Can be shifted, and when the exposure value Lv is greater than the upper limit exposure value Ev3, the combination of the control shutter speed Tv and the control aperture value Av can be shifted along the upper limit exposure value Ev3 line. Become.

Next, the program shift direction bit is checked (S507). If "0" (positive), the program shift amount is added to the control shutter speed Tv, and if the added control shutter speed Tv is larger than the maximum shutter speed TvMAX, the maximum shutter speed TvMAX is set to the control shutter speed Tv ( S507, S509-S51
3). If the program shift direction bit is "1" (negative), the program shift amount is subtracted from the control shutter speed Tv, and it is checked whether the control shutter speed Tv after the subtraction is less than the minimum shutter speed TvMIN. The minimum shutter speed TvMIN is set to the control shutter speed Tv (S507, S515 to S519).

Then, by calling the Av calculation subroutine, an appropriate control aperture value Av that can be controlled based on the control shutter speed Tv obtained as described above is obtained (S521).
It is checked whether the control aperture value Av is an appropriate value (S5).
23, S525). Here, if "1" is set in the Av over flag or the Av under flag, S
Since the control aperture value Av obtained in 521 is not an appropriate value,
The proper shutter speed Tv corresponding to the control aperture value Av is calculated again by calling the Tv calculation subroutine (S523, S52).
527 or S523, S527).

When the above processing is completed, step S50
In step 3, the exposure value Lv stored in the Lv memory is returned to the exposure value Lv, and the process returns (S529). By the above-described program shift processing, at the time of flash photography, the exposure value Lv is set to the minimum limit aperture value AvMINLMT and the minimum limit shutter speed T
Even when the aperture value is smaller than the value determined by vMINLMT, the aperture value Av can be shifted between the minimum aperture value AvMIN and the maximum aperture value AvMAX by the program shift processing as shown by the broken line in FIG. One can shift between the minimum shutter speed TvMIN and the synchronized maximum shutter speed TvMAX, and the shutter speed and the aperture value are linked within the range surrounded by the broken line.

As described above, according to the flash program of the single-lens reflex camera of the present embodiment, 1/100 is added to the film sensitivity Sv data.
The minimum limit aperture value AvMINLMT (fixed aperture value) is set using a variable weighted 2 (0 or more and less than 1), so when using high-sensitivity film, proper exposure is possible even for subjects at longer distances. Becomes possible. on the other hand,
For a subject at a short distance, the smaller the shooting distance D, the smaller the fixed aperture value. Therefore, even at a short distance, flash photography with an appropriate exposure value becomes possible.

Further, the flash program according to the present embodiment enables a program shift even in flash photography.
Since that, when flash photography is also a combination of the shutter speed Tv and the aperture value Av widely that can be set, it is captured by the combination according to the preferences of a wider shooting conditions and the photographer.

In this embodiment, the case where the external strobe 3 is mounted has been described. However, the present invention can be used for a camera having a built-in strobe, and is not limited to a single-lens reflex camera. The present invention is also applicable to a shutter type camera and the like.

[0052]

As is clear from the above description, the exposure control apparatus of the present invention is used when shooting with a strobe light emitting.
Sets the first minimum limit aperture value on the open side
Weighting the film speed more than 0 and less than 1
According to the first formula, the aperture is narrowed down as the sensitivity increases
Calculate and open second minimum limit aperture value
When the shooting distance detected by the shooting distance detecting means is shorter.
Calculate with the second formula
Because the aperture value is used for shooting,
First minimum limit value is selected when
However, although the film sensitivity is high, the narrowing down amount is small.
Effectively use strobe light even for distant subjects.
Exposure can be used to take advantage of film sensitivity characteristics
While the subject is in close range.
When setting the aperture, the second minimum
Mitt aperture value is selected, so even subjects at close range are exposed
Flash photography with proper exposure without overexposure
Wear.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of an embodiment of a single-lens reflex camera equipped with a flash program exposure control device of the present invention.

FIG. 2 is a main flowchart relating to a main operation of a CPU of the same-lens reflex camera.

FIG. 3 is a flowchart relating to photometry and calculation processing of the camera.

FIG. 4 is a flowchart relating to a program shift-up process of the camera.

FIG. 5 is a flowchart relating to a program shift-down process of the camera.

FIG. 6 is a flowchart showing a program strobe process of the camera .
It is a low chart.

FIG. 7 is a flowchart showing a program strobe process of the camera .
It is a low chart.

FIG. 8 is a flowchart showing a program strobe process of the camera .
It is a low chart.

FIG. 9 is a flowchart relating to a program shift process in a flash program of the camera.

FIG. 10 is a flowchart related to a shutter speed Tv limit process of the camera.

FIG. 11 is a flowchart relating to aperture value Av limit processing of the camera.

FIG. 12 is a program diagram illustrating a flash program line and a program shift of the camera.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Nobuhiko Matsudo 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Asahi Optical Industry Co., Ltd. (56) References JP-A-62-255924 (JP, A) Hei 4-50833 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B ^7/ 28-7/26 G03B ^7/ 00-7/28 G03B 15/05

Claims (3)

(57) [Claims] 1. A and photometric means, for calculating the film sensitivity setting unit, a photographing distance detecting means, the shutter speed and the aperture value based on the film speed set by the photometric value and the film speed setting means of the metering means Calculation means for setting the shutter speed and aperture value used for exposure control.
Comprising an exposure control means that, the said calculating means, the when you shoot Turning the Flash, the first minimum limit aperture value on the open side, and the weighting of greater than 1 than 0 to the film speed as well as calculated by the first formula film speed is narrowed high indeed stop, the second minimum limit diaphragm value of the open side <br/>, the shooting distance to the photographing distance detection unit detects are narrowed down closer The exposure control means calculates the aperture value of the first and second minimum limit aperture values calculated by the calculation means , the aperture value being the smaller one of the first and second minimum limit aperture values used in the exposure control. An exposure control device, which is set as an aperture value. 2. The exposure control apparatus according to claim 1, wherein when the strobe is fired, the interlocking range of the shutter speed is regulated between a strobe tuning limit speed and a lower speed limit shutter speed lower than this speed. An exposure control device having a flash program mode including an interlocking range in which an aperture value is fixed to the minimum limit aperture value that is equal to or greater than a minimum aperture value of a photographing lens and a shutter speed is changed within the interlocking range. 3. A exposure control apparatus according to claim 1 or 2, wherein the weighting is 1/2, if the apex value AvMINLMT the first minimum limit diaphragm value, the upper
Serial first equation, AvMINLMT = (5-AvMIN) / 2 + (Sv-5) / 2 + AvMIN = defined by Sv / 2 + AvMIN / 2, apex value AvMINL the second minimum limit diaphragm value
The exposure control device, wherein MT2 is defined as follows: AvMINLMT2 = 5−Dv + (Sv−3) / 2 = Sv / 2−Dv + 7/2. Here, AvMIN: Apex value of the open aperture of the photographing lens Sv: Apex value of the set film sensitivity Dv: log {shooting distance (m)} ² / log2