JPH01287638A - Flash-photographing device - Google Patents

Abstract

PURPOSE:To apply appropriate exposure to a main object so as to reproduce the impression of the main object taken against the light by controlling the exposure based on the output of a 1st photometric means which makes photometry on the main object at the approximate central part of a photographing picture and a 2nd photometric means which makes photometry on the background of the peripheral section of the main object. CONSTITUTION:In case of backlight, exposure is controlled by a microcomputer 1 so that the background of the peripheral section goes to over-exposure by a 1st prescribed quantity and, at the same time, the main object at the central part is exposed to the natural light and flash light. Moreover, in the case of follow light, exposure control is performed so that the main object goes to under-exposure by a 2nd prescribed quantity when a selecting means selects a forcible light emission mode and, at the same time, a flash light emitting means 16 emits flash light and the main object is exposed to the natural light and flash light. Therefore, appropriate exposure can always be made to the main object irrespectively the lighting condition whether it is backlight or not and, at the same time, the impression of the photographing scene taken against the light can be reproduced in a photograph.

Description

[Detailed description of the invention] "Weighing plate light to m" The present invention relates to a flash photography device.

2. Description of the Related Art Various types of flash photography devices have been proposed in the past as flash photography devices that take pictures with flash light.

For example, in Japanese Patent Application Laid-open No. 62-58229, exposure control is performed so that the background is overexposed when the light is backlit, and a flash is emitted.Thereby, the main subject is properly exposed, and the backlight appears in the photograph. A flash photography device W that can reproduce the impression captured in a scene has been proposed.

However, with this device, when shooting with flash in front light (when the difference in brightness between the main subject and the background is small, or when the main subject is brighter than the background), the background is Since the exposure is controlled to be appropriate, the main subject may end up being overexposed. In particular, when the main subject is brighter than the background, the main subject will be overexposed due to natural light alone, but since the flash light is also added, the main subject will be extremely overexposed.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a flash photography device that can always properly expose the main subject regardless of whether it is frontlit or backlit, and can reproduce the impression of a backlit scene in a photograph. .

In order to achieve the above-mentioned object, the flash photography device of the present invention comprises: a first photometer for metering the main subject located approximately in the center of the photography area; a second photometering means for photometering a background located in the background, and determining whether or not the object field is a backlit layer based on the output of the first photometering means and the output of the second light means. Backlight determination means; Flash emission means for emitting flash light; Selection means for selecting a forced flash mode in which photography is always performed with flash emission regardless of the brightness of the main subject and the brightness of the background; and the backlight determination means. When the means determines that the subject is in a backlit state, the means calculates an exposure control value so that the peripheral area is overexposed by a first predetermined amount, and the backlight determining means determines that the subject is in a backlit state. exposure control value calculation means for calculating an exposure control value so that the main subject is underexposed by a second predetermined amount when the selection means selects the forced flash mode; When the exposure control means for controlling exposure based on the exposure control value calculated by the exposure control value calculation means and the backlight determination means determine that the field is a backlit layer, or
A light emission control means is provided for causing the flash light emission means to emit light when the selection means selects the forced light emission mode.

In the flash photography device of the present invention having the above configuration,
When backlit, exposure control is performed so that the background is overexposed by a first predetermined amount, and the main subject is properly exposed by natural light and flash light. In addition, when the main subject is not in a backlit state, that is, in the case of front light, when the selection means selects the forced flash mode, the main subject is
Exposure control is performed so that the exposure is underexposed by a predetermined amount, and the flash light emitting means emits light, so that the main subject is properly exposed with natural light and flash light.

Actual Picture 11 A camera embodying the present invention will be explained with reference to the drawings. This camera can switch the focal length of the lens (38n+n+, 80mm), and can also be equipped with a teleconverter for telephoto shooting (focal length M105m).
This is a camera that can perform

[Overall Configuration] FIG. 1 is an overall block diagram of a camera embodying the present invention.

In the figure, numeral 1 denotes a microcomputer (hereinafter abbreviated as microcomputer), which controls the entire camera.

Reference numeral 2 denotes a main switch determining means, which outputs a signal S0 to the microcomputer 1 when a main switch (not shown) is ON. When this signal S0 is output, photographing becomes possible. 3 is a release signal generating means, and when a release button (not shown) is pressed down to the first stroke, a signal S1 is generated.
When the release button is pressed down to a second stroke, which is longer than the first stroke, a signal Sze is output.

Therefore, when the signal S2 is being output, the signal S1 is always being output. As will be described later, when the microcomputer 1 receives the signal Sl, it starts the photometry/distance measurement operation.
When the signal S2 is input, a photographing operation is performed.

4 is a forced light emission signal output means, which outputs a signal Sfl when a forced light emission switch (not shown) is ON.

As will be described later, when the microcomputer 1 receives the signal Sfl, the microcomputer 1 always causes the flash device 16 to emit light and performs photography (flash photography), regardless of the brightness of the scene.

Reference numeral 5 denotes a light emission prohibition signal output means, which outputs a signal 5nfl when a light emission prohibition switch (not shown) is ON. As will be described later, when the microcomputer 1 receives the signal 5nfl, the microcomputer 1 always turns on the flash device 16 regardless of the brightness of the subject.
Take pictures without using the flash (natural light photography).

Reference numeral 6 denotes a focal length switching signal output means, which outputs a pulsed focal length switching signal Sst in synchronization with a focal length switching switch (not shown) being turned on. When the microcomputer 1 receives this signal Sst, the focal length switching means 18
A signal is sent to switch the focal length of the photographing lens, and a signal is output to a flash light distribution switching means 17 and a finder switching means 19 to switch the flash light distribution and the finder according to the switched focal length.

Note that each of the switching means 17, 18, and 19 is constituted by a well-known means, so a description thereof will be omitted. Also,
The pulse width of the signal Sst is shorter than the time required for these switches, but is set to a somewhat longer time (for example, 0.1 seconds).

Reference numeral 7 denotes a teleconverter detection means, which outputs a mounting signal Stc when a teleconverter is mounted on the camera.

Reference numeral 8 denotes a back cover opening/closing detection means, which outputs a signal S back indicating whether or not the back cover (not shown) is closed.

As will be described later, when the microcomputer 1 detects that the back cover changes from the open state to the closed state, it outputs a signal to the film winding means 20 to cause the film to be initially loaded.

Reference numeral 9 denotes a rewind signal output means, which outputs a rewind signal Sr- when the film reaches the final frame or when a rewind switch (not shown) is turned on. As will be described later, when the microcomputer 1 receives the signal Srw, it outputs a signal to the film rewinding means 21 to cause the film to be rewinded.

The switches (not shown) provided in each of the above means 2 to 6 and 9 are not limited to mechanical switches, but may also be electrical (e.g., touch switches), optical (e.g., photocouplers), etc. It may also consist of
Each detection by the teleconverter detecting means 7 and the back cover opening/closing detecting means 8 may be performed using any mechanical method using a movable member, an electrical method using conductivity, an optical method using a photocoupler, etc. You may do so.

Reference numeral 10 denotes a film sensitivity reading means, which reads the film sensitivity from the DX code formed on the cartridge, converts it into an APEX value, and then outputs film sensitivity information Sv to the microcomputer 1.

Further, the film sensitivity reading means 10 has an operating member that is manually operated, so that the film sensitivity information Sv to be output can be changed according to the intention of the photographer.

Reference numeral 11 denotes a charge detection means, which detects whether the main capacitor (not shown) in the flash device 16 is charged. The S voltage is the voltage required to emit flash light (e.g. 300V).
) is detected, and if the charging voltage of the main capacitor reaches a voltage that allows flash emission, a charging completion signal Scc is output.

12 is a distance measuring means, which receives a control signal C from the microcomputer 1.
Based on TRL, the photographing distance of the subject within a plurality of distance measurement areas within the photographic screen is measured, and distance measurement data Z is output. Reference numeral 13 denotes an external light type photometry means, which measures the brightness of a subject within a plurality of photometry zones within the photographic screen based on a control signal CTRL2 from the microcomputer 1, and outputs photometry data By. These two means 12.13 will be described in more detail later.

Reference numeral 14 denotes a lens driving means, which drives the lens based on data output from the microcomputer 1 and performs focus adjustment.

Reference numeral 15 denotes a shutter driving means, which opens and closes a shutter (not shown) which also serves as an aperture blade, based on a signal output from the microcomputer 1.

The flash device 16 receives a trigger signal S from the microcomputer 1.
A flash is emitted in response to x, and the boost control signal S
In response to dd, a booster circuit (not shown) is controlled.

Note that each of the means 14 to 21 is a well-known means, so a detailed explanation thereof will be omitted.

[Overall control] Next, the operation of the microcomputer 1 will be explained.

FIG. 2 is a flowchart showing the operation of the microcomputer 1. When the power is turned on, the microcomputer 1 starts operating according to this flowchart.

First, the microcomputer 1 checks whether the rewind signal Srw is being output (#10). If the rewind signal Srw is being output, the process proceeds to #11; if the signal Srw is not being output, the process proceeds to #15. Proceeding to #11, the microcomputer 1 outputs the boost control signal Sdd to stop charging the main capacitor, and stops the operation of the boost circuit. Thereafter, a signal is output to the film rewinding means 21 to cause the film to be rewinded (#12), and the process returns to #10.

Proceeding to #15, microcomputer 1 checks whether the back cover is open or closed. If the back cover is open, proceed to #2o; if the back cover is closed, proceed to #16. In #16, microcomputer 1 checks the open/closed state of the back cover. Check the opening/closing status of the back cover, and if the back cover was open last time, it is determined that the back cover has just been closed, and proceed to #17. If not, proceed to #20, #17
In step #11, the microcomputer 1 stops the voltage increase, proceeds to step #18, outputs a signal to the film winding means 2o to perform initial loading of the film,
After that, return to #10.

Proceeding to #20, the microcomputer 1 checks the state of the main switch, and if the signal S0 is output, the microcomputer 1 proceeds to #21 and outputs the signal S. If not output, proceed to #28.

In #21, the microcomputer 1 checks whether the teleconverter is installed. If the signal Stc is output, the process proceeds to #22; if the signal Stc is not output, the process proceeds to #2.
Proceed to step 3. In #22, the microcomputer 1 determines the focal length of the photographic lens, and determines if the focal length is short focus (38 mm) fil.
If it is l, proceed to #24, and if it is on the long focus (80 mm) side, proceed to #26. As described above, in the camera of this embodiment, when the teleconverter is attached, the focal length of the photographing lens is always set to the long focal length (80m+*) side, and as described later, the focal length of the photographic lens is set to #24. Proceeding, at #25,
(The focal length of the lens can be changed.) By the way, in short focal length photography, the angle of view is wider than in long focal length photography, so if you attach a teleconverter, part of the screen may be vignetted. However, since the camera of this embodiment is always set to long focal length photography when the teleconverter is attached, no vignetting occurs due to the teleconverter.

In #23, the microcomputer 1 checks the state of the focal length switch (not shown), and if the signal SsL is output,
Proceed to #4, and if the signal Sst is not output, proceed to #26. Proceed to #24, where the microcomputer 1, as in #11,
Stop pressurization. After that, proceed to #25 and microcomputer 1
The flash light distribution switching means 17 and the focal length switching means 1
8. Output a signal to one finder switching means to switch flash light distribution, focal length, and finder. Thereafter, the microcomputer 1 returns to #10 and continues processing. As mentioned above, since the signal SsL disappears at this time, even if the focal length changeover switch is kept on, the focal length changeover operation will not be performed continuously.

In addition, a flag (referred to as Fst for convenience) is provided that is set immediately after the focal length has been switched, and it is determined whether or not flag Fst is set on the way from #23 to #24, and flag Fst is set. #2 if it is
4. Omit #25 and skip to #10, flag Fs
If t is not set, the flag Fst may be set and the process proceeds to #24. In this case, #23
If the signal Sst is not output in the flag F
After resetting st, proceed to #26. In this case, the focal length switching signal output means 6
While the focal length switch (not shown) is ON, the signal S
It is also possible to continue outputting st.

At #26, the microcomputer 1 checks whether the signal S1 is being output, and if the signal S1 is being output, the microcomputer 1 checks #30 if the signal S1 is being output.
If the signal S1 is not output, the process goes to #27. In #27, the microcomputer 1 checks the charging state of the main capacitor, and if the main capacitor has been charged and the signal Scc is output, the process goes to #27. Proceed to #28, and if charging is not completed and signal Scc is not output, proceed to #29
Proceed to.

In #28, the microcomputer 1 stops boosting the voltage as in #11, and then returns to #1o. In #29, microcontroller 1
outputs the signal Sdd to activate the booster circuit to charge the main capacitor, and then returns to #10.

At #26, when it is detected that the signal S is being output, that is, the release button (not shown) has been pressed down to the first stroke, and the process proceeds to #30, the microcomputer 1 stops the pressure increase and then , Proceed to #32. In #32, the microcomputer 1 checks and stores the states of the forced light emission switch and the light emission prohibition switch (not shown), and proceeds to #34.

As will be described later, in the camera of this embodiment, it is determined whether or not the flash prohibition signal SnN is output before the forced flash signal Sfl (see FIG. 18). If you accidentally turn on the forced flash switch and the flash prohibition switch shown in the figure at the same time, you will end up shooting with natural light. By the way, it is usually better to use daytime synchronization than when shooting with the flash disabled. Since there are many cases where the flash is forced to fire when taking photos, etc., when both signals Sfl and 5nfl are output, the photographer can use the flash prohibition switch when selecting the forced flash mode. The states of the forced light emitting switch and the light emitting inhibiting switch may be stored, assuming that the forced light emitting switch and the light emitting inhibiting switch are mistakenly turned on, and that only the forced light emitting signal Sf+ is output, and that the light emitting prohibition signal 5nfl is not output.

At #34, the microcomputer 1 inputs film sensitivity information Sv from the film sensitivity reading means 10. Then, proceed to #36 to perform photometry and distance measurement operations, and #3
Proceed to step 8.

In #38, the microcomputer 1 determines a lens stop point Zs according to the shooting distance of the subject based on the plurality of distance measurement data Z. Thereafter, the microcomputer 1 proceeds to #40 and performs exposure calculations based on the plurality of distance measurement data Z, the lens stop point, the plurality of photometry data Bv, etc., and obtains shutter and flash control data. In addition, the above 3
Steps #36, #38, and #40 will be detailed later.

After completing the exposure calculation in #40, the microcomputer 1 determines whether or not it is necessary to fire the flash based on the calculation result (#50>, if it is necessary to fire the flash, the microcomputer 1 determines whether or not it is necessary to fire the flash. Proceed to #52, check the state of charge of the main capacitor, and if the main capacitor has been fully charged, proceed to #54 to stop the boost operation, then proceed to #56; conversely, check the state of charge of the main capacitor. If charging is not completed, the microcomputer 1 proceeds to #53 to start boosting operation, and then proceeds to #58 (that is, prohibits shirt release when charging is not completed). On the other hand, if the flash is not required in #50, microcontroller 1 may issue an unfilled warning in #50.
Proceed to step 6.

In #56, the microcomputer 1 determines whether the signal S2 is being output, that is, whether the photographer has pressed the release button (not shown) to the second stroke to perform a photographing operation. If the signal S2 is being output, the microcomputer 1 proceeds to #60 and performs a photographing operation.

In #56, if the signal S2 is not output, the microcomputer 1 proceeds to #58 and checks whether the signal SI is output, that is, whether the release button (not shown) remains pressed until the first stroke. judge.

Then, if the signal S1 is output, the microcomputer 2 #
The process returns to #50, and if the signal S is not output, the process returns to #10.

Therefore, in the camera of this embodiment, focus lock and AE lock are achieved by pressing and holding the release button (not shown) until the first stroke.

When detecting that the signal S2 is being output in #56 and proceeding to #60, the microcomputer 1 first performs focus adjustment, that is, the microcomputer 1 outputs a signal to the lens driving means 14, and then proceeds to #38. The lens is extended to the lens stop point determined in step.

Next, the microcomputer 1 sets the time tc until the shutter is closed and the time Ld until the flash is emitted, based on the shutter and flash control data obtained in #40 (#62).

Note that when shooting with natural light, do not set the time td, and reset and start the built-in timer (
#64) At the same time, a shutter opening signal is output to the shutter driving means 15 to start the shutter opening operation (#66).

After starting the shutter opening operation, the microcomputer 1
The time measured by the timer (measured value of exposure seconds) t is the above time t
Check whether it is equal to e (#70).

If t=tc, the microcomputer 1 uses the shutter driving means 1
5, a shutter closing signal is output to start the shutter closing operation (#72), and the process proceeds to #74.

If t≠Lc, skip to #74. In #74, the microcomputer 1 determines whether or not flash photography is being used. If it is flash photography, the process proceeds to #75, and if natural light photography is being performed, the process skips to #78.

At #75, the microcomputer 1 checks whether the time measured by the timer is equal to the time td. If t=td, the microcomputer 1 sends a trigger signal Sx to the flash device 16.
Output and fire the flash (#76), #7
Proceed to step 8. If L≠td in #75, skip to #78.

In #78, the microcomputer 1 determines whether closing of the shutter is completed. This determination is made by detecting whether or not the time t counted by the timer has counted 2tc+α (α is a predetermined value) 3 times.

Alternatively, a switch may be provided that is turned ON when the shutter has been closed, and a bad condition of this switch may be detected.If the result of this determination is that the shutter has not been closed, the process returns to #70; If shutter closing has been completed, proceed to #80.

In addition, in #70 and #75, the microcomputer 1
As mentioned above, it is determined whether t-tc or t=td, but strictly speaking, the microcomputer 1 first determines whether t≧t
c, when t≧td, t= Lc, t= Ld
It has been determined that Therefore, microcomputer 1 is -
After outputting the shutter close signal and trigger signal S×,
The shutter close signal and trigger signal Sx will not be output again.Strictly speaking, the microcomputer 1 will not output the shutter close signal and the trigger signal Sx again.
e, when a time t such that t>td has elapsed, a shutter close signal and a trigger signal Sx may be output. However, since the processing speed of the microcomputer 1 is sufficiently fast and the accuracy of the timer is sufficiently fine, the error in the above determination can be ignored.

When shutter closing is completed and the process goes to #80, microcomputer 1
outputs a signal to the lens driving means 14 to retract the lens to the initial position. Then, the microcomputer 1 outputs a signal to the film winding means 20 to wind one frame of film (#85), and either the film winding for one frame is completed or a predetermined time has elapsed since the start of winding. (This is a slightly longer time than it takes to finish winding one frame of film; for example, 3 seconds). This means that the film is stretched at the last frame, and the signal Srw is (is output from the return signal output means 9), and the process returns to #10.

The above is the overall control of the camera of this embodiment.

According to this embodiment, while the release button (not shown) is pressed down to the second stroke and held, shooting is performed continuously, but after #85 it is determined whether the signal S1 is output. A step is provided, and the signal S1
It may be changed so that the process returns to #10 only after the is no longer output.Also, a means for switching between quick shooting and single shooting can be provided so that during continuous shooting, the process can unconditionally return from #85 to #10. When photographing, #10 is activated only after the signal Sl is no longer output.
In this case, it may be possible to switch back to natural light photography whenever continuous shooting is performed.

In addition, in the camera of this embodiment, the release was locked if the main capacitor had not been fully charged during flash photography, but the release was changed to proceed from #53 to #56. The photographing operation may be performed even if the charging of the camera is not completed.

Note that even with this modification, in the camera of this embodiment,
As mentioned above, when the main switch (not shown) is ON, the main capacitor is always being charged, so the probability of improper exposure is extremely small.

[Photometering/Distance measurement] Fig. 3 is a diagram showing the photometry areas of the photometry means 13.As shown in Fig. 0, three spot photometry areas L, C, and R are located approximately in the center of the photographing screen FRM. There is a peripheral photometry area 0tJT around them. These four areas L, C,
R and ○UT constitute the photometry area LMA,
The light-receiving means shown in the figure below, which is included in the photometry means 13, has areas L, C, and R, respectively.

○Receive the light incident on the UT individually. Then, the luminance of the incident light is converted into electrical power by each light receiving means, logarithmically compressed, and outputted to the microcomputer 1 as A PEX fa BV. Note that the specific circuit configuration of the photometric means is already well known, so a description thereof will be omitted.

Also, as is clear from the figure, the photometric area C.

Light from the main subject S mainly enters into R, and light from the background mainly enters into the photometry area OUT.

In this embodiment, there is only one photometry area where the light from the background mainly enters, but the peripheral photometry area OUT may be divided into multiple areas. There are three photometric areas, but there may be two, four or more photometric areas.

Distance measurement> FIG. 4 is a diagram showing the distance measurement area of the distance measurement means 12.
As shown in the figure, five ranging areas Z1 to Z are lined up in a horizontal row approximately in the center of the photographic screen FRM. The distance measuring means 12 measures the photographing distances of objects within these five distance measuring areas using a well-known active method. Then, the distance measuring means 12 detects which of the distance zones shown in Table 1 the measured shooting distance falls into, and outputs the zone number to the microcomputer 1 as distance measurement data Z.

The specific configuration of the distance measuring means 12 is shown in Japanese Patent Application No. 1983-20338 filed by the present applicant, so the explanation will be omitted. Of course, it is also possible to use a known active distance measuring means.

Fig. 5 shows #36 and #36 of the flowchart shown in Fig. 1.
38 is a flowchart showing a specific example of No. 38.

First, the microcomputer 1 sends a control signal CT R to the photometry means 13.
Output L2 and start photometry operation (#110),
The microcomputer 1 controls each photometry area C.

Photometric data Bvl, Bvc, Bv at R, 0LIT
r.

Read Bvout (#120 to #150).

Then, the microcomputer 1 sends a control signal CT to the distance measuring means 12.
RL, to measure the shooting distance of the subject within the distance measurement area Zl, and read the distance measurement data Z1 (#2
10), Similarly, the microcomputer 1
Distance measurement data Z 2 , Z 3 , Z 1.2, Z 3 , Z < , Z s. Read Zs (#220 to #250).

The above is a specific example of #36.

Thereafter, the microcomputer 1 detects the one with the shortest shooting distance among the distance measurement data Zl-Zs, that is, the one with the largest zone number among 71 to Z, and stores the zone number in the register Zs ( (indicating the lens stop point) (#38).Therefore, in this embodiment, focus adjustment is performed on the subject with the shortest photographing distance (nearest).

By the way, the distance measurement data Z, ~Z in each of the distance measurement areas Z1~Z includes measurement errors.

In the camera of this embodiment, the center distance measurement area 2. The distance measuring means 12 is adjusted based on the distance measuring area z,
, z2. The outputs of z, ,z, have a maximum error of about 2 in distance zone number with respect to the output of distance measurement area Z3. For example, the same subject or subject at the same shooting distance)
When distance measurement is performed, the output of each distance measurement area Z1 to Z may be as follows: Z, = 12 Z2 = 11 Zz = 10 Z, = 11 ZS = 12 In other words, each distance measurement area Z1 to
For example, if the output of Z is: Z,=6 Z2=5 Z,=5 Z,=4 Z5=4, the true shooting distance is Z2=4 Z,=5 Z,=3 Z,= It is also possible that it is 2. Therefore, in the camera of this embodiment,
When the difference between each distance measurement data is small, the center distance measurement area Z
The output of , is used preferentially. Specifically, the distance measurement areas z,,z2. z 4. If the difference between the distance measurement data of z and the distance measurement data of the center area Z is within 2, the distance measurement data of the area indicating the closest distance (Z+ in this example) is not set as the lens stop point, and the center Area Z of
The distance measurement data is used as the lens stop point. Thereby, the influence of distance measurement errors can be reduced.

[Exposure Calculation Next, a specific example of step #40 (exposure calculation) in FIG. 2 will be explained.

Overview> FIG. 6 is a flowchart showing an overview of the exposure calculation routine. When proceeding to this routine, microcontroller 1 first performs the following steps.
Initialize flags, etc. (#1000), then
Microcomputer 1 receives the photometric data (Bvout) obtained in #36.
etc.) to determine the backlight detection level δ (#105
0), next, the microcomputer 1 calculates the shooting distance from the AF data (lens stop point) Zs, and stores the APEX value in the register Dv #1100).
defines the range of the proximity zone (?&description) (#1150
), and the microcomputer 1 receives the distance measurement data Z , , Z 2
．． Z 3. Z1. #12 Based on Z and AP data Zs, select photometric data from among photometric data Bvl, Bvc, and Bvr to obtain center photometric value AEc.
00), center photometry li! Calculate A E c (#1
250), then the microcomputer 1 calculates the main subject photometric value Bv
Find s (#1300), then microcontroller 1 calculates
The microcomputer 1 determines the shutter control value E v-control, determines whether or not to use the flash, and sets the flag Ff1 (#1400).Then, the microcomputer 1 determines whether flash photography (Ffl=1) or natural light photography (Ffl=0) (#1500), if natural light photography, return to the main program (Figure 2), if flash photography, proceed to #1600, #1
In step 600, the microcomputer 1 determines the flash correction amount ΔEv, and then determines the aperture value Avd indicating the timing of flash emission (#1650).Then, the microcomputer 1 needs to repeat the calculation. If it is necessary to repeat the calculation, proceed to #1600; if it is not necessary to repeat the calculation, return to the main program (FIG. 2).

Description of each step> Next, each step of the flowchart shown in FIG. 6 will be described in detail.

"Initial Settings J" In this step, the microcomputer 1 resets the flash use determination flag Ffl and the shift counter SHI FT (described later), and also resets the flash light JI I v and the maximum aperture value (the aperture value corresponding to the minimum aperture diameter) Ayfia. ×
, maximum aperture value AVO, maximum value E of the shutter movement range
vmax and minimum value Ev theory in, camera shake limit value E
vh, predetermined brightness value HL, HL2(HL,>HL2,
(described later), shift amount e (described later), and upper limit number of shifts M (described later). Note that these values (excluding the upper limit number of shifts M) are expressed as APEχ values unless otherwise specified.

These values differ depending on the focal length of the photographic lens.

For example, in long focal length photography, the camera shake limit value Evh is larger than in short focal length photography. In addition, the open aperture value AVO of the photographic lens changes according to the switching of the focal length, and accordingly, the maximum aperture value A vmax, the maximum value Evm:n of the shutter movement range, and the minimum value E vmax
also changes. Therefore, the microcomputer 1 sets these values according to the focal length of the photographic lens. Note that when a teleconverter is attached, as mentioned above, the focal length of the photographic lens is always set to the long focal pressure side, and the maximum aperture value etc. of the photographic lens does not change even if the teleconverter is attached. is set to the same value as when shooting with a long focal length.

Further, when the signal 5nfl is not output and flash emission is not prohibited, the minimum value Evmin of the shutter interlocking range is replaced with the camera shake limit value Evh. Therefore, in the case of flash photography, camera shake does not occur.

[Determination of backlight detection level δ] As will be described later, the camera of this embodiment compares the difference between the peripheral photometry value AEa and the center photometry value AEc with the backlight detection level δ, and thereby determines the backlight detection level δ. Determining whether there is. Detecting bad backlight in this manner has been conventionally performed, but in conventional cameras, the backlight detection level δ was fixed, resulting in the following problems.

In an external photometry type camera that does not use light transmitted through a photographic lens, such as the camera of this embodiment, the photometry area is constant regardless of the focal length of the lens. Therefore,
When the photographing magnification is constant, that is, when the size of the subject S occupying the photographic screen FRM is constant, when the focal length of the lens changes, the photometry area LMA for the photographing range changes.

This will be explained in more detail with reference to FIG. In addition, in the same figure, (a) is short focal length M (standard)
When shooting, (b) has a long focal length! (Telephoto) shooting and (c) show when a teleconverter is attached, both showing the same shooting magnification. Also, (d), (e), (
f) shows a case where the shooting distance is different during telephoto shooting, and (e) shows a state where the shooting distance is shorter than (d), and (f) shows a shorter shooting distance than (e). There is.

As is clear from FIGS. 7(a) to (c), the photometry area LMA during standard shooting is narrower than during telephoto shooting. Therefore, during standard shooting, the proportion of the main subject S in the peripheral photometry area OUT is larger than during telephoto shooting, and the difference between the peripheral photometry value AEa and the center photometry value AEc is larger than that during telephoto shooting. It will be smaller when shooting.

In addition, the photometry area LMA when a teleconverter is attached is wider than when taking telephoto shots. Therefore, when a teleconverter is attached, the peripheral photometry area O
The proportion of the main subject S in the UT becomes smaller, and the difference between the peripheral photometric value AEa and the central photometric value AEc becomes larger when the teleconverter is attached than when telephoto shooting is performed.

Furthermore, as is clear from Fig. 7(d) to (f), even in the same shooting condition (telephoto shooting condition, standard shooting condition, or when a teleconverter is attached), the distance of the main subject S (shooting distance ) becomes longer, the proportion of the main subject S in the photometry area LMA becomes smaller, and the center photometry area L, C, H
The proportion of the main subject S in the image becomes small. Therefore, the central photometric value AEc is affected by the background brightness, and the difference between the peripheral photometric value AEa and the central photometric value AEc becomes small. .

In addition, even if the center photometry areas C and H are entirely covered by the main subject and no light from the background enters the areas C and H, the effects of crosstalk between each photometry element Accordingly, the photometric values Bvl in the photometric areas L, C, and R are
Bvc and Bvr may be affected by background brightness. The influence of this Talostalk between each photometric element becomes large when there is a light source such as the sun in the background peripheral photometric area OUT and the background brightness is high.

From the above, it is desirable that the backlight detection level δ changes its value depending on the focal pressure N of the lens (shooting condition), the distance to the main subject, and the peripheral brightness. Therefore, in the camera of this embodiment, the backlight detection level δ is given by a function δ=δ (focal length, shooting distance, background brightness) of the lens focal length, main subject distance (photographing pressure 111), and background brightness.

Note that in the camera of this embodiment, the peripheral photometric value AEa is
It is equal to the photometric value Bvout in the peripheral photometric area 0LIT, but if the peripheral photometric area OUT is divided into multiple areas, the average value, maximum value (brightest value) and minimum value (darkest value) of multiple peripheral photometric values BvouL The peripheral photometric value AEa may be an intermediate value between the maximum value and the minimum value, or an average value excluding the maximum value and the minimum value.

Next, a specific example of the backlight detection level δ will be explained with reference to FIG.

FIG. 8 is a graph showing the relationship between the background brightness Bvout and the backlight detection level δ, where A indicates the reference value, B, C
, D indicates the value corrected for the backlight detection level δ in consideration of the focal length of the lens and the main subject distance.
When vouL is Ev5, it is δ-1,5Ev, and when background brightness Bvout is BvlO, it is δ-1,25Ev. In this embodiment, the reference value A is set when the telephoto shooting state is in effect and the main subject distance is 111 or more and less than 2-.

Furthermore, as is clear from the figure, in the camera of this embodiment, the greater the background brightness 13vout, the higher the backlight detection level δ.
is made smaller. This makes it possible to reliably detect backlight even if there is a light source such as the sun in the background and the influence of cross and talk becomes large.

That is, as the background luminance B vout increases, the influence of crosstalk increases, and as a result, the peripheral photometric value A
Since the difference between Ea and the center photometric value A E c becomes small, it becomes impossible to accurately detect backlight on the high brightness side unless the backlight detection level δ is changed.

However, as in this embodiment, if the backlight detection level δ is made small on the high-brightness side, backlight detection can be performed accurately even if the influence of crosstalk becomes large.

Next, correction of the backlight detection level δ due to a change in the focal length of the lens will be explained. As described above, the difference between the center photometric value AEc and the peripheral photometric value AEa is smaller during standard shooting and larger when a teleconverter is attached, compared to when telephoto shooting. Therefore, in order to reliably detect backlight, the backlight detection level δ may be made smaller than the reference value A during standard photography and increased when a teleconverter is attached.

In the camera of this embodiment, the backlight detection level is corrected so that it is 0.125 Ev smaller than the reference value A during standard shooting, and 0.125 Ev larger when the teleconverter is attached.

Next, we will calculate the backlight detection level δ as the main subject distance changes.
The correction will be explained below.

If the main subject distance is extremely short (for example, less than 1 m), the peripheral photometry value AEa will be affected by the main subject and will be low (Note: Since we are considering backlight detection, the background brightness is the main subject. Higher than the subject brightness.

Therefore, when the main subject distance becomes short, the peripheral photometry area ○U
The proportion of the main subject S in T increases, and the peripheral photometric value AEa decreases. However, the center photometric value AEc is
(Since it corresponds to the main subject brightness, the center photometric value A E c does not change even if the main subject distance becomes shorter). Therefore,
When the main subject distance is extremely small, the center metering value AEc
The difference between the peripheral photometric value AEa and the peripheral photometric value AEa becomes smaller. Therefore, when the main subject distance is extremely short, it is desirable to reduce the backlight detection level δ.

On the other hand, when the main subject distance is long, the difference between the center photometric value A E c and the peripheral photometric value AEa becomes smaller, as described above, so the longer the main subject distance, the lower the backlight detection level δ. It is desirable to make it small.

Therefore, in the camera of this embodiment, when the main subject distance deviates from the reference range (1 ugliness or more and less than 2 wheels), the backlight detection level δ is corrected to decrease by 0.125 Ev.

To summarize the above, the relationship between the combination of shooting condition R (standard, telephoto, teleconverter attached) and main subject distance and the backlight detection level δ graph (A, B, C, D) shown in Figure 8. is as shown in Table 3.

Note that the method of determining the amount of correction is not limited to the one described above; the absolute value may be changed between positive and negative corrections, or when the main subject distance is longer or shorter than the reference range. The amount of correction may be changed depending on the background brightness Bv.
The relationship between ouL and the backlight detection level δ does not have to be linear, and the backlight detection level can be corrected arbitrarily.

"Determination of subject distance Dv" In this step, the microcomputer 1 calculates the APEX value Dv of the distance to the main subject.In the camera of this embodiment, this value Dv is calculated in advance and stored in the ROM. , and the microcomputer 1 reads the value Dv corresponding to the AF data (lens stop point) Zs from the ROM.
, Dv values are shown in Table 1.

“Determining the proximity zone range” When performing distance measurement in multiple distance measurement areas like the camera in this example, the distance measurement data for each distance measurement area is There are different things. This is because there are variations in distance measurement errors for each distance measurement area,
There may be differences in distance measurement data due to the depth of the subject.ζ
caused by.

Therefore, in the camera of this embodiment, each distance measurement data is compared and it is determined whether or not it should be considered that the same object is actually being measured even if the values are different (in this embodiment,
If the distance difference is within the range of the distance measurement error or the distance difference is within 15 cm, it is determined that the objects are the same). and,
In this specification, the range of distance zones that should be considered as distance measuring the same subject is defined as the proximity zone range.

Next, a specific method for determining the proximity zone range in the camera of this embodiment will be explained.

First, consider a first zone range that includes the lens stop point Zs and in which distance measurement data varies due to distance measurement errors. This zone range is expressed as a function of the lens stop point Zs: Zfl(Zs) to Zn,(Zs). However, Zf+(Zs) is the far side limit, Z
n, (Zs) indicates the near limit, and Zf+(Zs)≦Zs≦Z n, (Z s).

Next, consider a second zone range that includes the lens stop point Zs and in which distance measurement data varies depending on the depth of the subject. As is clear from Table 1, the shorter the shooting distance (larger Zs), the narrower the range of the distance zone. Therefore, the shorter the shooting distance, the greater the variation in distance measurement data. Therefore, the second zone range is also at the lens stop point Zs
is expressed as a function of That is, the second zone range is Z r 2 (Z s) to Z n2 (Z s)
It is expressed as However, Zf2(Zs), Znz(Zs
) are the far limit, respectively, as well as the first zone range.
Indicates the near limit, Zf2 (Zs)≦Zs≦Zn2 (Zs).

In the camera of this embodiment, these first. The union of the second zone ranges is defined as the adjacent zone range.

That is, the proximity zone range in the camera of this embodiment is: Zf(Zs) ~ Zn(Zs) Zf(Zs) = win [Zf, (Zs), Zf2
(Zs)]Zn(Zs) -wax [Zn+(Zs)
, Znz(Zs)], where -1n(a, b)
, wax(a, b) indicate the one that is not larger and the one that is not smaller among a and b, respectively.

Finally, the proximity zone range of the camera of this example is shown in Table 1 and in Figure 9. In Figure 9, the horizontal axis is the zone number indicating the main subject distance, and the vertical axis is the proximity zone range. The diagonal line and the boundary line indicate the proximity zone to each lens stop point Zs.

As is clear from Table 1 and FIG. 9, the shorter the main subject distance, the wider the proximity zone range.

“Selection of candidates for center photometry value A E c” The camera of this embodiment has three spot photometry areas L, C, and R.
Their spot photometric values Bvl.

Not all Bvc and Bvr correspond to the main subject, and some spot photometry values may correspond to the background. Therefore, in the camera of this embodiment, the respective spot photometric values Bvl and Bvc are calculated using distance measurement data.
, determine whether Bvr corresponds to the main subject,
The center photometry 1iaA Ec is accurately determined.

First, it is checked whether each distance measurement data Z, ~2° of the five photometric areas is within the proximity zone range.

If the distance measurement data is within the proximity zone range mentioned above, it is considered that the distance measurement data was measured for the main subject, so the spot light metering value of the spot metering area corresponding to that distance measurement area is used for the main subject. It is considered to be a photometric value corresponding to .

By the way, in the camera of this embodiment, as shown in FIG. 10(a), the distance measurement area and the spot photometry area do not have a one-to-one correspondence, so it is necessary to consider the correspondence between them. For example, one spot photometry area closest to each distance measurement area may be carried, or all or any number of spot photometry areas near each distance measurement area may be carried. As shown in (b), the distance measurement area and the photometry area are made to correspond. That is, the distance measurement area Z1 is connected to the spot photometry area R, the distance measurement area Z2 is connected to the spot photometry areas R and C, the distance measurement area Z is connected to the spot photometry area C, and the distance measurement area Z is connected to the spot photometry area C. L, ranging area Z,
corresponds to spot photometry area L.

Regarding photometry area selection, specific operations of the microcomputer 1 will be explained with reference to FIG. 11.

FIG. 11 is a flowchart showing the subroutine "selection of candidates for center photometric value AEc" in FIG. When proceeding to this routine, the microcomputer 1 first sets the flag Ll.
Reset r, Uc, Ul (#2100 to #212
0). These flags Ur, Uc, and Ul are set respectively when the photometric values B vr, B vc, and B vl in the photometric regions R1C and L are adopted when calculating the center photometric value AEc.

Subsequently, the microcomputer 1 determines whether the distance measurement data Zl in the rightmost distance measurement area Z1 is within the aforementioned proximity zone range. First, the microcomputer 1 compares the distance measurement data Z1 with the far side limit zr of the proximity zone range.
2200), if Z<Zf, that is, if the subject within the distance measurement area Z is farther than the main subject,
The process proceeds to #2250, and if Z1≧zf, the process proceeds to #2210. In #2210, the microcomputer 1 compares the distance measurement data 21 with the near limit Zf of the proximity zone range.
210), if Z > Z n, that is, if the subject within the distance measurement area Zl is closer than the main subject, proceed to #2250, and if Z1≦Zn, that is, the distance measurement area Z , if the subject within is the same as the main subject, the process advances to #2220.

In #2220, the microcomputer 1 determines the center photometric value AE.
When calculating c, a flag Ur is set to indicate that the photometric value Bvr in the photometric area R is adopted, and #225
Go to 0.

Proceeding to #2250, the microcomputer 1 determines whether the distance measurement data Z2 is within the proximity zone range or not.
．． #2260), if zr≦Z2≦Zn, flag U
Please set r and Uc #2270. #2280), #2
Proceed to 300. Similarly, set Uc and Ul.
Perform a reset.

Note that, as a matter of course, the lens stop point Zs is Zf
Since ≦Zs≦Zn is satisfied, the flag is Ur.

At least one of Uc and Ul is set.

"Determination of center photometric value, AEc" Next, how to obtain the center photometric value AEc will be explained.

In the camera of this embodiment, in front light, there are three photometry areas R.
, C, L photometric data B vr, B vc,
B The average value of vl AEcave is the center photometric value A E
c, and when the subject is backlit, the center photometric value AEc is determined according to the position and size of the main subject.

First, a method for determining the center photometric value AEc during backlighting will be explained.

FIG. 12 shows an example of the photometric value of the photometric means 13 used in the camera of this embodiment when the camera is backlit.

In the figure, the horizontal axis indicates the position of the main subject with respect to the center of the shooting screen, and the further to the right (left) in the figure, the further the main subject is located to the right (left). , the vertical axis indicates each spot photometry value with respect to the true main subject brightness Bvs0, and the higher you go in the figure, the brighter it becomes than the true main subject brightness BVS0.In the figure, Bva is true Back!: Indicates Icvi degree.

As is clear from the figure, each spot photometry value has the least error when the main subject is at the center of each spot photometry area, and the error increases as the main subject moves away from the center of the spot photometry area. For example, if the center position of the main subject is located at Xo to the left of the center of the shooting range,
When c=Ul=1 and Ur=0, the spot photometry values corresponding to the main subject are Bvc (point A) and Bvl (point B).As is clear, the photometry value Bvl in the spot photometry area L is Error<B vl -B vso) is the error (
B vc - B vso).

Therefore, in the case of backlighting, even if there are multiple spot light metering values corresponding to the main subject, it is not appropriate to consider their average value as the main subject brightness; rather, the minimum value of the multiple spot light metering values is the main subject brightness. It is more appropriate to consider it as luminance because it is less affected by errors.

However, even if it is the minimum value, an error remains, so it is necessary to further correct the error.

This error varies depending on at least the distance to the main subject, the brightness difference between the background and the main subject, the spot metering area, etc., so the following error function E = E < distance, brightness difference, photometering area) was considered and selected first. Further correct the minimum value.

By the way, since the photometry means 13 used in the camera of this embodiment is an external light type, the light receiving angle is constant regardless of the focal length of the photographic lens. In the TTL method that uses photometry, the light receiving angle varies depending on the focal length of the lens. Therefore, T
The error when the TL method is adopted is not a function of distance but a function of f-quadrant magnification, and the error function E is expressed as E=E (image magnification, brightness difference, photometry area). That is, the error function has slightly different properties between the external light method as in this embodiment and the TTL method.

On the other hand, if the main subject occupies a fairly large area with respect to the spot photometry areas R, C, and L, as shown in FIG.
There is no need to correct the photometric value; therefore, in the camera of this embodiment, it is determined whether the area occupied by the main subject with respect to the spot photometry area is large, and the photometric value is corrected according to the result.

Specifically, in the camera of this embodiment, as follows,
It is determined whether the area occupied by the main subject in the spot photometry area is large. First, it is determined whether most (or all) of the spot photometry areas L, C, and R correspond to the main subject. This determination is made using the flag Ul, as will be described later.

This is done by counting the set flags among Uc and Ur, and then calculating their spot photometric values B.
The variations in vl, Bvc, and Bvr are checked, and if the variations are small, it is determined that the range occupied by the main subject is significantly larger than the spot photometry area.

This variation is determined by comparing at least two of the maximum value, minimum value, and average value of the photometric values.

Next, a method for determining the center photometric value AEc in the case of front lighting will be explained. In the case of front lighting, unlike in the case of backlighting, spot photometry values are not affected by background brightness, etc., but errors occur due to the reflectance of the subject being measured.
It is not appropriate to use a single spot photometric value. Therefore, in the camera of this embodiment, the average value AEcave of all spot photometric values B vr, B vc, and B vl is used as the center photometric value AEc when the camera is in front light. It is said that

Note that the central photometric value AEc in front light is not limited to the average value of all spot photometric values, but may be any value that represents a plurality of spot photometric values. For example, the average value of the maximum and minimum spot photometric values (that is, the intermediate value of the spot photometric values) may be used as the center photometric value AEc, or the average value excluding the maximum and minimum values may be used as the center photometric value AEc. Photometric value AE
c may be used, and in this case, the influence of variations in spot photometry values can be suppressed. Furthermore, among the multiple spot photometric values, find the value that has the largest number of spot photometric values that fall within a certain range (for example, 0, 2 gv to +0, 3 EV), and calculate that value. The center photometric value AEc may also be used.

Specific center photometric value AEc of the camera of this example
The method for determining the value will be explained with reference to the flowchart shown in FIG.

Microcomputer 1 first calculates the average IAEcave of spot photometry values for #3100 and 1117 light.
-(Bvl+Bvc+Bvr)/3 is calculated.

By the way, the three spot photometric values are, as mentioned earlier,
Based on the distance measurement data, it is determined whether each object corresponds to the main subject (see FIG. 12), and the determination result can be found by checking the states of the flags Ur, Uc, and Ul. Therefore, it is also conceivable to calculate the average value of the Suboy I photometric values using only the spot photometric values corresponding to distance measurement areas where the flag is 1 (set).

However, in this case, only one spot photometric value may be used, and in that case, it is more susceptible to the reflectance of the subject, so it is not recommended as a center photometric value in front light. It's not appropriate.

Therefore, in the camera of this embodiment, the average value AEcaVe is always calculated using the three spot photometric values in #3100, regardless of the states of the flags Ur, Uc, and Ul.

When the average value AEcave of the spot photometric values is calculated, the microcomputer 1 calculates the three spot photometric values Bvr and Bvc.

Of Bvl, count the number Ns of spot photometry values that correspond to the main subject, and use it when backlighting.
Find the minimum value AEcmin among them.

First, the microcomputer 1 assigns O to Ns in #3110. In #3115, an appropriate initial value is assigned to AEc+ll1n. As this initial value, a preset value (for example, a large value that cannot actually occur) may be used, or an average value A E cave may be used.It goes without saying that However, this minimum value A
Ecnin must be converted into photometric data Bvl in a later step.
, Bvc, or Bvr.

Next, the microcomputer 1 checks in #3120 whether the flag Ur is 1, and if the flag Ur is 1, the process proceeds to #3122; if the flag Ur is not 1, the process proceeds to #3122.
In #3122, the microcomputer 1 increments the value of the counter Ns by 1, and then proceeds to #3125, where it compares the spot photometry value Bvr of the spot photometry area R at that time with AEcmin. B vr< A E cm
If it is in, the microcomputer 1 proceeds to #3128, replaces the minimum value AEcmin with the photometric value Bvr,
Proceed to #3130.

If Bvr≧AEc+*in in #3125, skip to #3130.

Thereafter, the counter Ns and the minimum value AEC are set in the same manner (#3130 to #3148).

Next, in order to determine whether it is backlit or frontlit, microcontroller 1 issues #
At step 3150, a value ΔBv is obtained by subtracting AEcIIlln from the peripheral photometric value AEa. In #3160, microcontroller 1
compares the difference △Bv and the backlight detection level δ, and calculates the difference △Bv
When the backlight detection level is 6 or higher (Δ[3v≧δ), the microcomputer 1 determines that there is backlighting and proceeds to #3170. Difference △
When Bv is smaller than the backlight detection level δ (ΔBv<δ), the microcomputer 1 determines that it is III light and proceeds to #3165.

Next, the microcomputer 1 determines the size of the main subject with respect to the photometry area of the pants 1. First, in #3170, the microcomputer 1 checks whether the count value Ns is 3 or not, and when the count fQNs is 3, that is, all three spot metering values correspond to the main subject. If so, proceed to #3175, otherwise #
Proceed to 3178. In #3175, the microcomputer 1 determines the difference between the average value AEcave and the minimum value AEciin of the spot photometric values in order to determine the dispersion of the spot photometric values.
Ecave-AEcmin), and if the difference is smaller than 05, proceed to #3180. If not, #
Proceed to 3178.

From the above, in the camera of this embodiment, #
Proceed to 3165 and correct the photometric value when backlit.If necessary, proceed to #3178.If correction is not necessary, proceed to #
It will proceed to 3180.

It is backlit and also corrects the photometry value! There is no need for pi #
When proceeding to 3180, the microcomputer 1 determines the center photometric value AEc.
After setting AEcmin to the minimum value AEcmin, the process returns to the original flowchart (FIG. 6). If it is backlit and the minimum value AEcmin needs to be corrected, and the process proceeds to #3178, the microcomputer 1 changes the center photometric value AEc to the minimum value AEe.
The value obtained by subtracting 1 (Ev) from min (A Ecmin
-1>. That is, in the camera of this example,
To simplify the process, the error function E is set to always take a constant value of 1, regardless of the shooting distance, brightness difference, or photometry area.

Of course, as mentioned above, the correction amount E may be changed depending on the shooting distance, n-degree difference, and photometry area.
After completing the Ec settings, the original flowchart (Figure 6)
Return to hell.

In the case of front light, when the process proceeds to #3165/\, the microcomputer 1 sets the center photometric value AEc to the average value AEcave, and returns to the original flowchart (FIG. 6).

"Determination of main subject photometric value BVS" Next, the main subject brightness B'V in the camera of this embodiment
The method for finding S will be explained. Note that since the processing methods are different depending on the case of front light and back light, these cases will be explained separately.

i) When I@light, basically the peripheral photometric value AEa and the central photometric value AEe
Let the weighted average value of the main subject brightness Bvs be the weighted average value of the main subject brightness Bvs. That is, the main subject brightness Bvs is expressed by the following equation 8%. As mentioned earlier, when the sun is shining,
AEc=AEcave.

As mentioned earlier, the sizes of the peripheral photometry area OUT and the spot photometry areas L, C, and H for the shooting range FRM differ depending on the focal length of the photographic lens (see Figure 7).
Therefore, it is not appropriate to uniformly determine the constant 4. When the photographic lens is in the standard photographing state (short focus side), even the peripheral metering area OUT is quite small relative to the photographing range FRM. The shooting range is FRM in the left and right direction.
In addition, the spot photometry areas L, C, and R are very small compared to the shooting range FRM. Therefore, in standard shooting, the constant value is used as the peripheral photometry value. It is necessary to set a value such that the weight of AEa becomes heavy. Conversely, when the teleconverter is installed, the peripheral photometry area OUT will be approximately the same size as the shooting range FRM, and the spot photometry areas L, C, and R will also be about 1/3 of the shooting range FRM in the left and right directions, so the center It is also necessary to give a certain degree of weight to the partial photometric value AEc.

In this way, the peripheral photometric value AEa and the central photometric value AEc
By changing the weight of , it is possible to obtain an effect similar to changing the apparent light receiving angle even in an external light type photometer as in this embodiment.

Note that this concept can be applied not only to a bifocal camera as in this embodiment but also to a zoom camera and the like.

Next, regarding exposure control at high brightness (BvlO or higher),
Let's consider this with reference to Figure 15.

FIG. 15 is a graph showing the relationship between brightness values and exposure correction values, where the horizontal axis shows the brightness values and the vertical axis shows the exposure correction values.

The brightness value of a subject having a standard reflectance when measured with a reflected light type exposure meter is almost always below BvlO even on a clear day, and very rarely reaches BVI0. On the other hand, white objects with high reflectance are
It is in the range of vl 2. Also.

When affected by a light source such as a snowy scene or the sun on a clear day, it may sometimes show a value of Byl 2 or more.

By the way, as shown in FIG. 15, conventional exposure control is one that controls the brightness to an appropriate level regardless of the brightness value (
(a) and (b) are known in which a luminance value equal to or higher than a predetermined luminance value is treated as being equal to the predetermined luminance value and controlled.

However, according to the former control, even if you take a photo with a high-brightness subject, the high-brightness feeling is not reflected in the photo and it gives an unnatural feeling.Therefore, it is difficult to reflect the high-brightness feeling in the photo. , it was necessary to make intentional exposure compensation based on the photographer's experience. In addition, it was easily affected by light sources such as the sun, and the main subject was often extremely underexposed.

On the other hand, according to the latter control, unlike the former, it is less affected by the light source, but the following problems arise.

As mentioned earlier, the brightness of an object with standard reflectance is
Although very rare, Bvl O may be reached, so in order to properly expose a subject having a standard reflectance, it is necessary to set the predetermined brightness value to BVI 0 or higher. As mentioned earlier, white subjects are
Since it is in the range of O to Bvl 2, if the predetermined value is set to ByIO, it is equivalent to adding 0 to +2 EV as the exposure compensation amount for a white subject. For example, if the brightness is Bvl
For a white subject with VI l, overexposure is corrected by +I Ev.

By the way, the amount of exposure compensation for a white subject is generally
It is said that around +2EV is appropriate. Therefore, for a white subject with a brightness of Bvl 1 as described above, the amount of correction will be insufficient. In such cases, in order to increase the amount of correction, it is necessary to lower the predetermined brightness value, but if the predetermined value is lowered too much, exposure compensation will be applied even to subjects with standard reflectance, which may not be appropriate. do not have.

Therefore, in the camera of this embodiment, at high brightness <BvlO or higher), the first predetermined brightness value and the second predetermined brightness value smaller than the first predetermined brightness value are combined, and the photometric value is set to the first predetermined brightness value. When a predetermined brightness value is exceeded, exposure control is performed using a second predetermined brightness value (Fig. 15(c)). This allows for the exposure range to be obtained without changing the range in which proper exposure can be obtained. For a bright subject, a larger exposure correction value than before can be applied, and it is possible to properly expose a subject having a standard reflectance, and it is also possible to reflect the appearance of high brightness.

In addition, in order to obtain this effect, when the photometric value exceeds the first predetermined brightness value (for example, BvlO), the exposure may be compensated to the overside by a first predetermined It (for example, IEv) (15th Figure (d)). Furthermore, when the photometric value exceeds a second predetermined brightness value (for example, Bvll) that is larger than the first predetermined brightness value (for example, Bvl O), a second predetermined brightness value that is larger than the first predetermined i (for example, IEV) is determined. The exposure may be compensated to the over side by l (for example, 2EV) (Fig. 15(e)).The situation of the subject may be estimated based on the distance to the subject, and the amount of compensation may be changed accordingly, or the amount of compensation may be adjusted accordingly. may be set to O.

The above is the method for determining the main subject photometric value Bvs in front light.

ii) In order to avoid the influence of the background in the case of backlighting, the center photometric value AEc is set as the main subject brightness Bvs. That is, Bvs=AEc.

Next, a two-body example of the method for determining the main subject brightness Bvs in the camera of this embodiment will be described with reference to the flowchart shown in FIG.

First, in #4110, the microcomputer 1 changes the brightness difference to BV (first
(see Figure 4 #3150) and the backlight detection level δ,
If △Bv≧δ, that is, backlighting, proceed to #4120,
If ΔBv<δ, that is, 1@light, proceed to #4150.

Then, in the case of front lighting, the microcomputer 1 changes from #4150 to #
4190, the weights of AEa and AEc are determined.

In the camera of this embodiment, the weight is determined by the ratio of the peripheral photometric value AEa and the central photometric value AEc, based on the photographic condition g (difference in focal length of the photographic lens) and the lens stop point Zs corresponding to the distance of the main subject. , is set to one of the following.

In #4150, microcomputer 1 checks whether a teleconverter is installed. If a teleconverter is installed (flag Ftc is set), the process proceeds to #4155, and if not installed (flag Ftc is set). When FLc is not asserted), proceed to #4170. In #4155, the microcomputer 1 checks whether -Zs≧2, and if 2S≧2, that is, Zs≠1, the process proceeds to #4
Proceed to step 160, and if Zs<2, that is, Zs=1, proceed to #4
Proceed to 190.

As will be described later, when proceeding to #4190, the peripheral photometric value A
The weight of Ea is increased because the main subject is far away and it is more appropriate to consider it as part of the background.

In #4160, the microcomputer 1 sets N=1 and sets the weight ratio of the peripheral photometric value AEa and the central photometric value AEc to 1:1. In other words, when shooting with a teleconverter installed [['
RM and photometry section rIfJLMA) rFIJ section (Figure 7 (c)
)), a large weight is also given to the center photometric value AEc. After setting N, proceed to #4200.

In #4170, the microcomputer 1 checks whether the focal length of the lens is on the long focal length side, and if it is on the long focal length side (if the flag F tele is set), it proceeds to #4175; Otherwise (if the flag F Lele is not set), the process proceeds to #4190.

In #4175, microcomputer 1 checks whether Zs≧3, and if Zs≧3, it proceeds to #4180 and checks Zs
<3, that is, when Zs=1 or Zs=2, #
Proceed to 4190. This is because, as mentioned above, the main subject is far away, and it is more appropriate to consider it as part of the background.

In #4180, the microcomputer 1 sets N=2 and sets the weight ratio of the peripheral photometric value AEa and the central photometric value AEc to 3:1. As is clear from No. 7'Q (b) and (c), when the telephoto condition is poor, the size of the photometry range LMA relative to the shooting screen FRM is smaller than when the teleconverter is attached, so the weight of the peripheral photometry value AEa is It is slightly larger than when the teleconverter is installed.

After setting N, proceed to #4200.

In #4190, the microcomputer 1 sets N=3 and sets the weight ratio of the peripheral photometric value AEa and the central photometric value AEc to 7:1.

As mentioned earlier, when in standard shooting conditions, or
Proceed to #4190 only when it is better to consider the main subject as part of the background because the main subject is far away. In the standard photographing state, as is clear from FIG. 7(a), the photometric area LMA becomes much smaller than the photographing range FRM, and the main subject occupies most of the photometric area LMA.

Therefore, in the camera of this embodiment, in such a case, the peripheral photometric value AEa is given a large weight.

When proceeding to #4200, microcontroller 1 executes the previous step (#4200).
4160. #4180. The main subject brightness Bvs is calculated based on the weight of the peripheral photometric value AEa and the central photometric value AEc determined in #4190). Furthermore, as mentioned earlier,
In the camera of this embodiment, in front light, AEc=AEcave
However, this makes it possible to reduce the influence of differences in reflectance of the main subject.

After determining the main subject brightness Bvs, the process proceeds to #4210, where the microcomputer 1 compares the main subject brightness Bvs with a first predetermined brightness value HL of 1 degree high (for example, BvlO), and
When ≧HL, the process proceeds to #4220, and when Bvs<HL, the process proceeds to #4290. In #4220, the main subject brightness Bvs is set to a second value smaller than the first predetermined brightness value HLl.
Replace with the predetermined brightness value + (L2 (for example, By9),
The process returns to flowchart 1 shown in FIG. That is, in this example, the correction shown in FIG. 15(c) is performed.

On the other hand, if it is backlit and the process proceeds to #4120, the microcomputer 1 substitutes the center photometric value AEc for the main subject brightness Bvs. As mentioned earlier (see Fig. 14), the value of the center photometric value AEc in this case is AEmin or (A E s
in -1>, then the process returns to the flowchart shown in FIG.

In addition, a modified example in which the control during high brightness in front light is limited to the case of long distances is shown in FIG. 17.
Step #4215 is added to the part within the dotted line in FIG. 6, and other steps are omitted.

In #4215, the microcomputer 1 mentally determines whether the lens stop point Zs is Zs=1, and when Zs=1, the process proceeds to #4220, and when Zs≠1, that is, Zs≧2, the process continues as shown in FIG. Return to flowchart 1 shown in . That is, in this modification, the main subject brightness Bvs is corrected only in the case of front lighting, high brightness, and long distance.

Note that the reason why the distance is limited is that high brightness control is performed only in cases such as snowy scenes.

[Determination of shutter control value EV-control and flash use determination] Next, step #14 of the flowchart shown in FIG.
A specific example of 00 will be explained with reference to FIG.

First, the microcomputer 1 turns on the light emission prohibition switch (not shown).
It is determined whether or not (#5100).

If it is determined that the flash prohibition switch is ON based on the information stored in #32 in FIG. 2, the microcomputer 1
Go to 0, otherwise go to #5120, #511
0, the microcomputer 1 has E v-control =
The calculation B vS+S v is performed and the process proceeds to #5300.

Proceeding to #5120, the microcomputer 1 determines whether it is backlit or frontlit.

When photographing a distant scene with a camera that detects backlight and automatically fires the flash, the flash light hardly reaches the subject, so there is no point in firing the flash.Therefore, the camera in this example , #5120
When it is determined that there is backlight (ΔBy≧δ), microcomputer 1
Determine whether the main subject is far away #5130)
, when the main subject is close to some extent (in this example, Zs≧2)
), backlight is detected and the flash is automatically emitted (#5150).

Flag Ffl indicating flash emission in #5150
After setting (backlight automatic light emission), the microcomputer 1 sets the peripheral photometry value AEa and the first predetermined high brightness value HL, (
For example, compare Bvl O), and if AEa is HLl, go to #5170, AEa≧HL.

If so, proceed to #5180.

In #5170, microcomputer 1 sets the background to IEv over to express the appearance of backlighting.

Shutter control value E v-control (AEa-
1) Substitute the value of +SV and proceed to #5250. Note that the amount by which the background is exceeded does not necessarily have to be lEv, and may be any other value.

When proceeding to #5180, that is, if the peripheral photometric value AEa is equal to or higher than the predetermined brightness value HL, it is possible that the background is quite bright or that there is a light source in the background. Therefore, in the camera of this embodiment, the shutter control value E v-control is set to a predetermined value HL and a second smaller value.
Substituting the sum of the predetermined brightness value HL2 and film sensitivity SV and proceeding to #5250, that is, Ev-control
= HL2+Sv. This makes it possible to more clearly express the high brightness of the background when backlit, and furthermore, it is possible to reduce the influence of the background light source.

Note that in #5180, the number of times the background is overshot may be greater than the amount (IEV) of overlapping the background in #5170. For example, set E v-conLrol so that the background is over 2Ev (AEa-2) +
The value of SV may be substituted.

When it is determined that it is front light in #5120 (△Bv × δ)
, or when it is determined in #5130 that the main subject is far away (Zs=1), the microcomputer 1 proceeds to #5140 and determines whether forced light emission is being performed or not.

The process proceeds to #5140 only when the flash is not to be fired as a result of backlight detection, but in the camera of this embodiment, when the photographer turns on the forced flash switch (not shown) to perform Franche photography, the process proceeds to #5140. I try to respect the photographer's intentions when using flash photography. Therefore, in #5140, when the microcomputer 1 detects that the forced flash switch is ON based on the information stored in #32 in FIG. 2, it sets the flag Ffl to the cellar 1-L (# 5190), the process advances to #5200, and if it is detected in #5140 that the forced light emission switch is OFF, the process skips to #5200.

In #5200, microcomputer 1, like #5110, E v-control = B vs + S v
After performing the calculation, the process proceeds to #5250.

In #5250, the microcomputer 1 sets the shutter control value E
v-control and the exposure value Evh corresponding to the camera shake limit (low-speed light emission switching point) are compared, and E v-co
If ntrol≦Evh, proceed to #5260 and Ev
- If control>Evh, skip to #5300.

In #5260, the microcomputer 1 sets the flag Ffl to cause the flash to emit light (low brightness automatic light emission).
, and then proceeds to #5300.

Next, the microcomputer 1 determines the shutter control value E v-
Determine whether control is within the shutter interlocking range (#5300 to #5330). First, the microcomputer 1 uses the obtained shutter control value Ev-contr.
ol and the maximum value E vmax of the shutter control value (#5300), E v-control > E
If vmax, the shank-control value E v-cont
Reset rol to the maximum value E vIIIax (#53
10), and shutter control value E v-cont
Compare rol with the minimum value Evmin of the shutter control value #5320), E v-control (E vn
If it is in, the shutter control value E v-control
is reset to the minimum value Evmin (#5330).

After setting the shutter control value Ev-control and the flag Ffl in this way, the process returns to the flowchart shown in FIG.

Note that according to this flowchart, when forced light emission is performed, the main subject may be overexposed. Therefore,
The steps #5140 to #5200 may be changed as shown in FIG. 19 to expose the main subject as appropriately as possible, as described below.

First, the microcomputer 1 determines in #5140 whether or not it is a forced light emission, and if it is not a forced light emission, the E
If it is 0 forced light emission, which calculates v-control = B vs + S v, after setting the flag Ffl (#5190), the microcomputer 1 determines whether the main subject is far away (#5195). As a result of the judgment, if the main subject is far away (Zs=1), microcomputer 1 selects #5.
Proceed to 200 and enter the shutter control value Ev-control
Set. On the other hand, if the main subject is close to some extent (
Zs≧2), the microcomputer 1 has E v-control=
Bvs+1+Sv is calculated to obtain a shutter control value Ev-control.

In this way, in the case of forced flash, if the main subject is close to a certain extent, the main subject's constant light exposure is controlled to be underexposed by IEV, so if this deficiency is compensated for by flash light, the main subject can be photographed. Allows you to properly expose the subject. However, in this case, the background is underexposed by IEv. Also, if the main subject is far away, the shutter control value is set so that the main subject is properly photographed using only constant light, but even if the flash is used, the flash light will not reach the main subject. The main subject will not be overexposed.

"Determination of Flash Correction Amount ΔEvfl" In conventional flash photography, natural light components are ignored and proper exposure is provided only with flash light. Therefore,
When the natural light component cannot be ignored, especially during daytime synchro photography, the subject becomes overexposed. Furthermore, there is also a camera that changes the flash emission timing only in the case of daytime synchronized photography and controls the exposure by the flash light to be under-exposure by a predetermined amount with respect to the appropriate exposure value.

However, depending on the situation of the subject, it may not be possible to provide an appropriate exposure simply by under-exposure by a predetermined amount. Furthermore, even in the case of flash photography at low brightness, natural light components may not be negligible.

Therefore, in the camera of this embodiment, the natural light (stationary light) component of the main subject is always taken into consideration when shooting with flash, regardless of whether the brightness is low or backlit, and the flash light is used to compensate for the insufficient amount of light from the natural light component alone. , controls the flash emission. As a result, the main subject is always properly exposed.

When the shutter control value is E v-conLrol, the main subject brightness is Bvs, and the film sensitivity used is SV, the difference △Bvs between the main subject's exposure value and the appropriate exposure value when exposed with only natural light is △B vs= B vs −(E v-conLrol
−3v). For example, IS○100 (Sv=
5> film, B vs= 2, 5,
In the case of E v-conLrol-8,5, △Bvs=-
1, and when exposed with only natural light, the main subject is IEv
will be underexposed.

By the way, if the amount of light required to properly expose the main subject is 1, the amount of light provided by natural light (that is, the ratio of natural light to the appropriate amount of light) is 2. For example, if the main subject is exposed only with natural light, When properly exposed (i.e. ΔBvs=0>,
Natural light is 1. Also, when exposing the main subject with natural light only, it will be underexposed by IEV (i.e. △
BV3=1), natural light will be halved. Furthermore, when exposing the main subject using only natural light, the exposure will be underexposed by 2Ev (ΔBvs=2), the natural light will be reduced to 1/4. And if there is no natural light, △Bvs=−ω
becomes. Therefore, the amount of light that is insufficient with natural light alone, that is, the amount of light that needs to be supplemented by ΔBvs for flash light, is 1-2, compared to the case where the main subject is properly photographed using only flash light (when the amount of flash light is 1). The main subject cannot be properly exposed unless the amount of flash light is reduced. If the correction amount of this flash light l is 8EvrI in APEX value, then ΔBvs ΔEvfl=log2(12) For example, when there is no natural light (ΔBvs=
-■), ΔEvfl=0, and the main subject will not be properly exposed unless the flash light is emitted so that the main subject will be properly exposed with just the flash light. Also, if the main subject is underexposed by IEv with natural light only (ΔBvs = 1>, △Evfl = 1), and if you fire the flash so that it is underexposed by IEv with only flash light, the main subject will be underexposed by IEv with natural light and flash. In addition, if natural light alone results in an underexposure of 2Ev (ΔBvs-2),
ΔEvrIζ−0.42, and if the flash is emitted so that the main subject will be underexposed by about 0.42 Ev with only the flash light, the main subject will be properly exposed with natural light and flash light. If the main subject is properly exposed using only natural light (△Bvs=0), ΔE
vf l =-■, and it can be seen that the flash light is -off and unnecessary in order to properly expose the main subject.

The difference ΔBvs between the exposure value of the main subject and the appropriate exposure value when exposed with only natural light, and the flash correction amount ΔEv
FIG. 20(a) shows the relationship with fl, and FIG. 20(b) shows the relationship between the difference ΔBνS and the flash light ff1 (the ratio of the flash light amount to the i-direct light amount). In both figures, the horizontal axis shows the difference ΔBvs, the vertical axis in FIG. 20(a) shows the correction amount ΔEvfl, and the vertical ΔBvs axis in FIG.

As is clear from the figure, the greater the amount of underexposure (-ΔB vs) caused by natural light alone (the smaller ΔB vs), the smaller the absolute value of the flash correction amount ΔEvfl, and the greater the amount of flash light. Conversely, the above difference ΔBvs
The smaller the absolute value 1ΔBvs1, the greater the absolute value 1ΔEvil of the flash correction amount ΔEvfl, and the smaller the amount of flash light.

By the way, as is clear from both sections, when the absolute value 1ΔBvsl of the difference ΔBvs is small (for example, −〇,
5≦ΔBvs<0), the flash correction amount △Evrl changes rapidly, but the flash light intensity does not change much. Also, if the absolute value of the flash correction amount △Igvfl is too large, the effect of the flash light will not be reflected in the photo. It will no longer be done.

Therefore, in the camera of this embodiment, a lower limit is set for the correction amount ΔEvfl, so that a predetermined amount of flash light is applied even when the amount of flash light to be compensated for is very small (see Figure 21). In the camera of this embodiment, the lower limit of the correction IΔEvfl is set to -2Ev. Setting the lower limit of the correction amount ΔEvf1 in this way makes it possible to obtain the correction amount ΔEvN by approximate calculation, which simplifies the calculation algorithm for the correction amount ΔEv(I. In addition, in FIG. 21, (a) is the difference ΔBvs and the correction amount ΔE
(b) shows the relationship between the difference ΔBvs and the amount of flash light.

By the way, as mentioned earlier, the camera of this embodiment has an automatic flash mode that fires the flash automatically depending on the brightness of the subject, and an automatic flash mode that fires the flash regardless of the brightness of the scene. It has a strongly controlled light emission mode. In the forced flash mode, that is, when the photographer turns on a forced flash switch (not shown), the photographer suddenly uses the flash and wants to reflect the effect of the flash light on the photograph. In such cases, it is undesirable to add corrections that reduce the effect of the flash, especially large corrections, as it goes against the photographer's intention.Therefore, the camera in this example uses forced flash mode. In this case, the lower limit of the flash correction amount ΔEvfl is set larger than in the automatic light emission mode. Specifically, in the camera of this embodiment, as shown in FIG. 22(a), the lower limit of Ev'I to the correction amount is set to -IEv. In the camera of this example, when in forced flash mode, the amount of flash light is:
It accounts for at least 1/2 of the appropriate amount of light. Also, the second
As is clear from Figures 1 and 22, when the main subject is bright to some extent (when the absolute value of the difference ΔBvs is small)
In , the forced flash mode produces more flash light than the automatic flash mode.

Note that if a lower limit is set for the correction amount ΔEvfl, the main subject will be overexposed, but as mentioned earlier, in the camera of this embodiment, the exposure is controlled so that the background is overexposed by a predetermined amount when backlit. Therefore, when backlit, the main subject will not be overexposed compared to the background.

By the way, as mentioned above, the correction amount ΔEvfl is obtained by a very complicated calculation using a mixture of logarithms and exponents. However, in an actual camera, the photometry means 13
The photometric data obtained by the above method includes errors, and when taking into consideration errors in shutter control accuracy and flash light intensity, there is little point in determining the correction amount ΔEvfl accurately. Therefore, in the camera of this embodiment, FIGS.
As shown by the broken line in the figure, the correction amount ΔEv41 is approximately calculated using a step-like function. In addition, in the camera of this embodiment, in order to prevent the main subject from being underexposed due to excessive correction of the flash light intensity, the correction amount is set so that it does not become larger than the correct value (the absolute value of the correction amount △Evfl becomes smaller). The correction amount ΔEvfl is approximated as follows. Therefore, with the camera of this embodiment, the main subject may be overexposed, but considering that the latitude of the film is wider on the overside than on the underside, the main subject may be slightly overexposed. Even if it's overexposed, it's not really a problem.

Next, a specific method for calculating the correction amount ΔEvfl in the camera of this embodiment will be explained with reference to FIG.

Flowchart I shown in FIG. 23 is a specific example of step #1600 (subroutine "determination of flash correction amount ΔEvfl") of the flowchart shown in FIG.

Proceeding to this subroutine, the microcomputer 1 first calculates the above-mentioned difference in exposure values ΔBvs (#5500), then the microcomputer 1 determines whether or not it is in the forced flash mode (#5510). When the microcomputer 1 detects that the forced light-emission switch (not shown) is ON based on the information stored in FIG. Calculate the correction amount ΔEvfl. On the other hand, the forced flash switch is set to O.
If it is FF, the microcomputer 1 proceeds to #5520 and calculates the correction amount △ based on the graph shown by the bold line in FIG. 21(a).
Find Ev41. After determining the correction amount ΔEv41, the microcomputer 1 returns to the flowchart shown in FIG.

"Determination of Aperture Value Avcl Indicating Flash Emission Timing" Next, the control of the flash noche in the camera of this embodiment will be explained.

As mentioned earlier, the camera of this embodiment uses a so-called lens shutter in which the shutter blades also serve as aperture blades, and when the shutter aperture reaches the appropriate size while the shutter blades are opening. fires the flash. Flash intensity is Iv, film sensitivity is S
v, and the APEX value of the shooting distance of the main subject is Dv,
As is well known, if the aperture aperture is Avdo==Iv+5v-Dv, the main subject will be properly exposed only by flash light. To do this, for example, the time tdo from when the shutter starts opening until it reaches the aperture corresponding to the aperture value Avdo is calculated in advance based on the aperture characteristics of the shutter, and when the time tdo has elapsed since the shutter opened, All you have to do is fire the flash.

By the way, in the camera of this embodiment, as described above, the amount of flash light is corrected in consideration of natural light components even during flash photography. In this case, the corrected type ΔEvrI
By reducing the aperture aperture by an amount corresponding to the absolute value of and firing the flash, the main subject will be properly exposed with natural light and flash light. That is, the aperture diameter is A vd = A vdo-△EvfI=rv+5v-
If the flash is emitted when the aperture reaches Dv-ΔEvfl [Avd, the main subject will be properly exposed with natural light and flash light.

Figure 24 shows the shutter aperture characteristics of the camera of this example. In the figure, the horizontal axis shows the time since the shutter started opening, and the vertical axis shows the shutter aperture (aperture aperture). The further you go, the larger the aperture value (the smaller the aperture diameter). In the figure, A vdo is the aperture value that will properly expose the main subject with only flash light, and Avd is the aperture value that is corrected after correcting the aperture value AvdO so that the main subject will be properly exposed with natural light and flash light. This is the aperture value.

As is clear from the figure, the aperture aperture is at both aperture values Avdo,
The time required to reach Avd is tdo
, td.

In addition, in the figure, Avc is the shutter control value E v
- an aperture value determined based on control,
tc is the time required for the aperture aperture to reach the aperture [Avc], and when the time tc has elapsed since the shutter started opening, the microcomputer 1 outputs a signal to the shutter control circuit 15 to start the shunter closing movement ft. . As is clear from the figure, the shutter control waveform has a triangular shape. Further, Avo is the maximum aperture value of the aperture, and when a very dark subject is photographed using only natural light, the shutter control waveform becomes trapezoidal, as shown by the broken line. Note that tc' is the timing at which the shutter is turned off in this case.

By the way, in the camera of this embodiment, as described above, the amount of flash light is corrected so that the amount of light that is insufficient with natural light alone is compensated for by the flash light. In such a camera, when the flash light does not sufficiently reach the main subject, such as when the main subject is far away, the main subject may be underexposed. Therefore,
In the camera of this embodiment, if there is a possibility that the flash light will not reach the main subject sufficiently, the shutter control value Ev-co
ntrol is shifted to the overexposure side to increase the proportion of natural light.

The appropriate shift amount in this case is determined by considering various conditions.
It can be determined by calculation.

However, in the camera of this embodiment, in order to simplify the algorithm, the shutter system tWI M E v-c
.

The computation for flash control is repeated while shifting ntrol by a predetermined amount e. Also,
An upper limit M of the number of shifts is set to prevent the background etc. from being extremely overexposed due to an excessively large shift amount.

Here, let us consider the upper limit M of the number of shifts from 1 to the number of shifts of the shutter control value Ev-control, and the amount of one shift e.

In the case of backlight photography, the camera of this embodiment sets the shutter control value Ev-c so that the background is overexposed by IEv compared to the proper exposure, as described above.

ntrol is set. When the flash light does not sufficiently reach the main subject, the shutter control value is shifted by e to the overexposure side. That is, E v-co
nLroi = Ev-control-e. In this case, the background will be overexposed by 1+e relative to the correct exposure. If the shutter control value is shifted n times, the background will be overexposed by 1+ne. As long as the amount of overexposure is within the latitude of the film, there will be no problem with the photograph. For example, if it is a negative film, the latitude on the overexposure side is about +3, so l + Me = 3,
It is sufficient to determine the upper limit of the number of shifts, M=4. e-0,
5 or M = 2, e = 1, the upper limit M and the predetermined amount e may be determined arbitrarily, taking into consideration the accuracy of exposure control, calculation speed, etc. Of course, the upper limit M and the predetermined amount e may be determined arbitrarily based on the DX code of the film. Load the latitude information of
Accordingly, the upper limit M and the predetermined amount e may be changed.

Next, the shutter control value E in the camera of this embodiment
A specific example of the method of shifting v-conLrol will be described with reference to FIG. 25.

First, the microcomputer 1 calculates the aforementioned aperture value Avcl (#6100). Next, the microcomputer 1 calculates the aperture value Awe (24th (see figure)
Find (#6110). In the camera of this embodiment, the aperture value Avc corresponding to the shutter control value E v-control is determined in advance based on the clever waveform of the shutter, stored in the eROM, and read out from the ROM when necessary. That's what I do.

Next, the microcomputer 1 resets the flag C0NT (
#6120). This flag C0NT is the shutter 1i
IHRIil! Shift Ev-control L fs
? , : Set when it is necessary to calculate the aperture values Avd and Avc again.

After resetting the flag C0NT, the microcomputer 1 determines whether the flash light sufficiently reaches the main subject.

First, the microcomputer 1 uses the aperture value Avd determined in #6100.
and the maximum aperture value of the shutter (the aperture value corresponding to the minimum aperture) Avmax (#6150), and then A vd > A vmax, that is, even if the flash is fired at the minimum aperture, the flash light and natural light will be different. If the main subject becomes overexposed, proceed to #6155 and reset the aperture value Avd to Avmax. This is the maximum aperture value (the aperture value corresponding to the minimum aperture).
This is because the flash cannot be emitted at a timing corresponding to an aperture value larger than vnax. When the microcomputer 1 resets the aperture value Avd, the 6th
Returning to the flowchart shown in the figure.

If Avd≦Av...ax in #6150, the microcomputer 1 proceeds to #6160 and compares the aperture values A and vd determined in #6100 with the aperture value Awe determined in #6110. If Avd≧Avc, if the flash is fired when the aperture value of the shutter aperture reaches Avd (when time td has elapsed since the shutter started opening), the main subject can be photographed properly using natural light and flash light. Therefore, no correction is made and the process returns to flowchart 1 shown in FIG.

On the other hand, if A Vd < A vc in #6160, even if the shutter is opened to the aperture aperture determined based on the shutter control value E v-control and the flash is emitted, the flash light is insufficient and the main subject is Therefore, in order to increase the ratio of natural light to the proper exposure and properly expose the main subject, the microcomputer 1 sets the shutter control value E v-cont.
#617 to shift rol to overexposed side
Go to 0.

In #6170 to #6190, the microcomputer 1 determines whether shifting the shutter control value EV-control will not cause any problem.

#6170 checks the difference △Bvs between the exposure value of the main subject and the appropriate exposure value when the exposure is not performed using only natural light, and if △Bvs≧0, that is, the main subject is properly exposed or exposed using only natural light. When overexposure occurs, the microcomputer 1 sets the shutter control value E v-control.
Proceed to #6175 without shifting the aperture value Avd.
By resetting the aperture value Avc, the degree of overexposure of the main subject can be minimized.

In #6170, if △Bvs<O, #618
0, and microcomputer 1 sets the aperture value A obtained in #6110.
It is determined whether vc is equal to the open aperture value Avo.

If Avc=Avo, that is, even if the shutter control value E v-control is shifted further, the timing of flash emission cannot be delayed, and the amount of flash light given to the main subject cannot be delayed any more. If it is not possible to increase the aperture value, the process proceeds to #6175, where the aperture value Avd is reset to the aperture value Awe, and subsequent shifts are canceled. This allows the main subject to be exposed as accurately as possible.

In #6180, if Avc+Avo, the microcomputer 1 proceeds to #6190 and sets the shutter control value E v-c.
It is determined whether the number of shifts 5HIFT of ontrol has reached the upper limit M. And the number of shifts SHI FT
has reached the upper limit M, proceed to #6175 and set the aperture value A.
vd is reset to the aperture value Avc, and subsequent shifts are prohibited.

In #6190, the number of shifts SHI FT is the upper limit M
If the value has not been reached, the microcomputer 1 proceeds to #6200 and sets the shutter control value Ev-control]L
Shift to the overexposure side by e. That is, E v-control = E v-control
-e.

After shifting the shutter control value E v-control, the microcomputer 1 changes the shutter control value E to the shifted shutter control value E.
It is determined whether the shutter can be controlled based on v-control (#6210).

That is, the microcomputer 1 compares the shifted shutter control value Ev-control with the minimum value Evmin of controllable shutter control values. And E v-c.

If nLrol<Ev wheel in, that is, if shutter control is impossible, the microcomputer 1 proceeds to #6220 and sets the shutter control value Ev-control to the minimum shutter control value Evmin that allows shutter control. Correct and proceed to #6230, while E v-con
If trol≧Evmin, that is, if shutter control is possible, skip to #6230.

In #6230, the microcomputer 1 increments the counter 5HIFT indicating the number of shifts, and then increments the counter 5HIFT in #624.
0, in order to obtain the aperture value Avd again, the flag CoN
Tf! :set. Then, the process returns to the flowchart shown in FIG.

As is clear from the above, in the camera of this embodiment, the aperture value Avc calculated based on the shutter control value Ev-control reaches the open aperture value Avo (in other words, the state in which the shutter is opened to the maximum or until IFT reaches the upper limit M, the shutter control value Ev-control is shifted.

[Modification] In the camera of the embodiment described above, the photometry area LMA of the photometry means 13 is divided into three areas C and R in the center and the areas around them, as shown in FIG. a certain area OU
It was divided into four parts. However, as described above, the photometric area LMA is not limited to this, and various other types can be considered. Therefore, a modified example of the photometric means having a different photometric area from that shown in FIG. 3 is shown below, and the shutter control H(a E
The method for determining v-control will be explained.

FIG. 26 shows the photometric area of the photometric means of this modified example. As is clear from the figure, the photometric area LMA of this modified example is:
It is composed of a rectangular first central photometric area P located at the center of the photographing screen FRM, a rectangular second central photometric area Q existing around it, and a peripheral photometric area R around it. There is. The size of the first central photometric area P is
The size of the photographing range when the focal length of the photographic lens is 2001 is determined to be approximately equal to the size of the photographing range.
When combined with light training area Q, the focal length of the photographic lens is 1.
The size of the photographing range is set to be approximately equal to the size of the photographing range when the value is 001. And the entire photometric area LM
The size of A is such that the focal length of the photographic lens is 50 mm.
The size of the shooting range is set to be approximately equal to the size of the shooting range when .

This photometric area LMAf! : Shutter control glE v-control in a camera equipped with photometry means
The method for determining l will be explained. Note that this camera is equipped with a zoom lens whose focal length can be changed from 281 to 135+@Im, and each focal length of the photographic lens will be explained below.

(1) When the focal length of the photographic lens is set to 35 mm In this case, as shown in No. 27 [2I], the photographing range FRM
is slightly larger than the photometric area LMA.

Therefore, at this time, there are three photometric areas P and Q.

By making the weights of the photometric values B Vp, B vq, and B vr in R equal, the shutter control value E v-cont
Find rol.

That is, Ev-control=(Bvp+ Bvq+ Bvr
)/3 + Sv.

(It) When the focal length of the photographic lens is set to 50 mm In this case, as described above, the photographing range FRM is almost equal to the photometry area LMA. Therefore, in this case, since the main subject is usually located at the center of the shooting range FRM, and in order to reduce the influence of the sky, etc., which is likely to exist in the periphery, photometry is performed in the outermost photometry area R. The value Bvr is not adopted, and the first and second central photometric areas P,
The shutter control value E v-control is determined by equalizing the weights of the photometric values B vp and B vq in Q. That is, E v-control= (B vp
+ B vq)/2 + S v.

(Ill) When the focal length of the photographic lens is set to 100m+* In this case, as mentioned earlier, the photographing range FRM is equal to the sum of the first central photometric area P and the second central photometric area 14Q. become almost equal. Therefore, in this case, the main subject is usually located in the center of the photographing range Fl" (M), and in order to reduce the influence of the sky, etc., which is likely to exist in the periphery, Using only the photometric value Bvp at P, the shutter control value E v-co
Find ntrol.

That is, Ev-control=Bvp+Sv.

(■) When the focal length of the photographic lens is set to a focal length other than the above (+) When the focal length is less than 3511 m In this case, the shutter control value Ev is set in the same way as when the focal length of the photographic lens is set to 35 mm. -cont.
Find rol. That is, E v-control=
(B vp+ B vq+ B vr)/3 + S
It is v.

(ii) In the case of 100mm or more In this case, the focal length of the photographing lens should be 10011u++
In the same way as when setting the shutter control value E v
- Find control. That is, E v-con
trol=B vp+S v.

(iii) In other cases, the focal length of the photographing lens should be 35mm to 5011.50Ml.
When set to 5 to 110C1n, each photometry area P is adjusted according to the focal length of the photographic lens, as shown in FIG.
, Q , photometric value I3 vp at R, B vq,
The shutter control value EV-control is determined by continuously changing the weight of B vr. Note that in this modification, the weights of the photometric values Bvp, Bvq, and Bvr are changed linearly, but needless to say, the weights of the photometric values Bvρ, Bvq, and Bvr are changed so that the sum of the weights becomes 1. ,
It may be changed in a curved manner.

Table 1 Table 2 Standard...Standard (Short focal length gi> Shooting 38mm Telephoto...Telephoto (Long focal length M) Shooting 80mmTC...
When equipped with a teleconverter, it is equivalent to 105111II! Introduction 14
<As explained above, the flash device of the present invention can always properly expose the main subject, regardless of whether it is frontlit or backlit, and reproduces the impression shown in Photo 2 in the backlit scene. can do.
Tsushi(.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of a camera embodying the present invention, and FIG. 2 is a flowchart 1- showing the overall control of the camera. FIG. 3 is a diagram showing the photometry area of the distance measurement means in a camera embodying the present invention, and FIG. 4 is a diagram showing the distance measurement area of the distance measurement means. FIG. 5 is a flowchart showing control of the distance measuring operation and the distance measuring operation in the camera implementing the present invention. FIG. 6 is a flowchart showing the overall control of the exposure B calculation operation in the camera implementing the present invention.5. FIG. 7 is a diagram showing the photometry range in each shooting state in the camera implementing the present invention. Yes, (a), (b) (c)
indicates the case when the shooting magnification is constant, and is that? This shows the standard shooting condition, the telephoto shooting condition, and the teleconverter installed condition. In addition, (d), (e), and <f) show cases in which the shooting distance is changed in the telephoto shooting state, where (d) is long distance, (e) is medium distance, and (f) is short distance. It shows. FIG. 8 is a graph showing the relationship between the peripheral photometric value and the backlight determination level. FIG. 9 is a graph showing the relationship between the main subject distance and the proximity zone in a camera implementing the present invention. 10th
The figure is a diagram showing the relationship between a photometry area and a distance measurement area in a camera implementing the present invention. FIG. 11 is a flowchart illustrating the operation of selecting candidates for central photometry values in a camera embodying the present invention. FIG. 12 is a diagram showing errors in photometry values in each spot photometry area during backlighting in a camera implementing the present invention. FIG. 13 shows a camera implementing the present invention.
FIG. 7 is a diagram showing the relationship between the photometry area and the main subject when the imaging magnification is very high. FIG. 14 is a flowchart showing a method for determining a center photometric value in a camera implementing the present invention. FIG. 15 is a graph showing the relationship between subject brightness and its correction amount, and (,) and (b) are graphs showing the relationship between the subject brightness and its correction amount.
e), (d), and (e) show cameras implementing the present invention. FIG. 16 is a flowchart showing a method for determining the main subject brightness in a camera implementing the present invention, and FIG. 17 is a flowchart showing a modification thereof. FIG. 18 is a flowchart showing a shutter control value determination method and flash usage determination in a camera embodying the present invention, and FIG. 19 is a flowchart showing a modification thereof. Figures 20 to 22 show the difference between the shutter control value and the main subject brightness, (a) the flash correction amount, and (b)
FIG. 20 is a graph showing the principle of the ratio of the flash light amount to the appropriate light amount. FIG. 21 is a graph showing the relationship during automatic flash firing in a camera implementing the present invention. , also shows the relationship during forced light emission. FIG. 23 is a flowchart showing a method for determining a flash correction amount in a camera implementing the present invention. FIG. 24 is a graph showing the aperture characteristics of the lens shutter. FIG. 25 is a flowchart showing a method for determining the timing of flash emission. FIG. 26 is a diagram showing a modified example of the photometric area of the photometric means in a camera embodying the present invention, and FIG. 27 is a diagram showing a modified example of the photometric area of the photometric means in a camera employing the modified example of the photometric means in short focal length photography. , is a diagram showing a photometry area and a photographing range 3. FIG. 28 is a graph showing the relationship between the focal length of the photographing lens and the weight of the photometric value in each photometric region for determining the shutter control value in a camera employing a modified example of the photometric means. Photometry means 13 Backlight determination means #3150. #5120 Flash emission means 16 Selection means 5 Exposure control value calculation means #5140J5170. #519
8 Exposure control means #64 to #72 Light emission control means #74 to #76# 5150.
#5190 Applicant: Minolta Camera Co., Ltd. 'Figure 26 Pavilion Figure 27

Claims (1)

[Claims] (1) a first photometer that measures the main subject located approximately at the center of the photographic area; a second photometer that measures the background that is located at the periphery of the photographic area; and an output of the first photometer; a backlight determining means for determining whether or not the subject is in a backlit state based on the output of the second photometric means; a flash emitting means for emitting flash light; a selection means for selecting a forced flash mode in which photography is always performed with flash emission, and when the backlight determination means determines that the subject is in a backlit state, the peripheral area is exposed by a first predetermined amount. The exposure control value is calculated so that the exposure is over, and if the backlight determination means determines that the subject is not backlit, and the selection means has selected the forced flash mode, the main subject is an exposure control value calculation means for calculating an exposure control value so that the exposure is underexposed by the predetermined amount of 2; an exposure control means for controlling the exposure based on the exposure control value calculated by the exposure control value calculation means; If the determining means determines that the subject is backlit, or
A flash photographing device comprising: a light emission control means for causing the flash light emission means to emit light when the selection means selects a forced light emission mode.