A photo taking apparatus capable of making a photograph with flash by a flash device

A flash modulation control apparatus in a camera having a photo-taking lens and a flash device mounted thereon comprises a photographing mode setting device for setting a photographing mode in which optimal exposure is obtained in conformity with an object, a divisional photometry device for dividing the object field into a plurality of areas, metering through the photo-taking lens light emitted from the flash device and reflected by the object, and outputting photometric values, a weighting device for determining an amount of weighting for each of the photometry areas of the divisional photometry device in conformity with the photographing mode set by the photographing mode setting device, and weighting each of the photometric values on the basis of the amount of weighting, and a light modulation control device for stopping the light emission of the flash device when the sum total of the weighted photometric values reaches a predetermined level.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a flash modulation control apparatus in a camera 
of the TTL automatic light modulation type, and particularly an apparatus 
for setting a photographing mode in conformity with an object, and 
effecting light modulation control in accordance with the photometry area 
and light amount level of the object field optimal to the photographing 
mode. 
2. Related Background Art 
There is known a flash modulation control apparatus in a camera of the TTL 
automatic light modulation type which effects light modulation so that 
after the light emission of a flash device is started during flash 
photographing, the light emission of the flash device may be stopped when 
the amount of reflected light from an object reaches a predetermined light 
amount level, whereby proper exposure may be obtained. 
The photometry area of the apparatus of this kind is substantially the 
whole of the photographing image field, or a relatively wide range 
including the center of the image field. Also, the light amount level 
which determines the timing of the stoppage of the light emission is 
determined on the basis of light reflected at a predetermined proportion 
relative to a certain predetermined amount of light emitted. For example, 
an object having a certain predetermined reflectivity (average 
reflectivity) is disposed in opposed relationship with the flash device so 
as to cover an area for effecting photometry, and a TTL light amount level 
is determined on the basis of such a relation between time and light 
amount that the object is photographed at proper exposure during flash 
emission. 
However, the reflectivity of the object field during ordinary flash 
photographing is not uniform and therefore, when flash photographing is 
effected by the use of a conventional device, there arises the problem 
that exposure becomes over or under depending on the object. 
For example, if the number of persons or bodies which are main objects 
increases or decreases, the area that main objects lying at the same 
distance occupy for the photometry area in the photographing image field 
varies and the amounts of reflected light from these main objects vary. 
However, the amount of light emitted from the flash device is controlled 
on the basis of a TTL light amount level determined with an object of the 
average reflectivity supposed and therefore, if the number of main objects 
increases, the amount of reflected light increases and light emission is 
stopped early and thus, the exposure for the main objects becomes under. 
If conversely, the number of main objects decreases, the amount of 
reflected light decreases and the time when light emission is stopped 
becomes late, and the exposure for the main objects becomes over. A 
similar phenomenon occurs when lenses of different focal lengths are used. 
That is, if the focal length becomes smaller (if a wide angle lens is 
used), the size of the main object in the photographing image field 
becomes smaller and the background range photographed becomes wider and 
therefore, the amount of reflected light from the main object decreases 
and the time when light emission is stopped becomes late, and the exposure 
for the main object becomes over. On the other hand, if the focal length 
becomes greater (if a telephoto lens is used), the size of the main object 
in the photographing image field becomes larger and the background range 
photographed becomes narrower and therefore, the amount of reflected light 
from the main object increases and the time when light emission is stopped 
becomes early, and the exposure for the main object becomes under. 
Also, in the prior-art apparatus, reflected light from an object is metered 
in the whole of the photographing image field or a wide range including 
the central portion of the image field, and this also leads to the problem 
that proper exposure is not obtained for a main object when the main 
object occupies a relatively narrow range in the photographing image field 
or when the main object is not at the center of the image field. 
SUMMARY OF THE INVENTION 
It is the object of the present invention to provide a flash modulation 
control apparatus in a camera for setting a photographing mode in 
conformity with an object, and effecting the light modulation control of a 
flash device in accordance with the photometry area and light amount level 
of the object field optimal to the photographing mode, thereby obtaining 
optimal exposure in conformity with the object.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the present invention, as shown in FIG. 1, weighting means 104 effects 
weighting to each photometry area of divisional photometry means 103 in 
conformity with a photographing mode set by photographing mode setting 
means 102, and outputs the photometric value of each weighted photometry 
area. Light modulation control means 101 effects the light modulation 
control of a flash device 100 on the basis of the photometric value of 
each weighted photometry area. 
In the present invention, as shown in FIG. 2, optimal light amount level 
setting means 105 sets an optimal light amount level in conformity with a 
photographing mode set by photographing mode setting means 102, and light 
modulation control means 101A stops the light emission of a flash device 
100 when the photometric value of photometry means 103A reaches the 
optimal light amount level. 
In the present invention, as shown in FIG. 3, weighting means 104A effects 
weighting to each photometry area of divisional photometry means 103 on 
the basis of the result of the focus detection by focus detecting means 
106 when a photographing mode for effecting light modulation control in 
response to the focus detecting means 106 is set by photographing mode 
setting means 102A, and outputs the photometric value of each weighted 
photometry area. Light modulation control means 101B effects the light 
modulation control of a flash devcie 100 on the basis of the photometric 
value of each weighted photometry area. 
Some embodiments of the present invention will hereinafter be described 
with reference to the drawings. 
FIG. 4 is a block diagram showing the construction of an embodiment. 
In FIG. 4, the reference numeral 1 designates a control circuit comprised 
of a microcomputer and various parts around it. The control circuit 1 
executes a control program which will be described later and effects the 
light modulation control of a flash device 2 and also controls the various 
operations of a camera. The reference numeral 3 denotes a switch adapted 
to be closed when a shutter release button, not shown, is half-pushed, and 
the reference numeral 4 designates a switch adapted to be closed when the 
shutter release button is fully pushed. The reference numeral 5 denotes an 
image mode selecting circuit for selecting image modes such as a fantasy 
mode, a wedding mode and a balance synchro spot mode which will be 
described later. The image mode selecting circuit 5 selects photographing 
conditions so that a photograph as per the photographer's intention may be 
obtained. The reference numeral 6 designates a lens information input 
circuit which receives as an input the information of the fully open F 
value, the focal length, the exit pupil, etc. of a photo-taking lens from 
a lens ROM, not shown, which is provided in a photo-taking lens barrel. 
The reference numeral 7 denotes a DX code detecting circuit for detecting 
film speed information recorded on a film cartridge, the reference numeral 
8 designates a photometry circuit for metering the interior of the 
photographing image field and outputting brightness information, the 
reference numeral 9 denotes a focus detecting circuit for detecting the 
focus adjusted state of the photo-taking lens, and the reference numeral 
10 designates an exposure control circuit for driving a shutter portion 
10a and a stop portion 10b. 
The reference numeral 11 denotes a divisional light receiving element for 
receiving light emitted from the flash device 2 and reflected by an 
object. The divisional light receiving element divides the interior of the 
photographing image field into five areas as shown in FIG. 5, and outputs 
the photometric value of each of these areas. The reference numeral 12 
designates a light modulation circuit for effecting the flash modulation 
control of the flash device. The light modulation circuit 12 outputs a 
light emission stopping signal FS for stopping the light emission of the 
flash device 2 when the integrated value of the photometric value from the 
divisional light receiving element 11 reaches a predetermined value. Sx 
denotes a syncro contact adapted to be closed when the shutter is fully 
opened and start the light emission of the flash device 2, and the 
reference numeral 13 designates an AF motor driving circuit for driving an 
auto focus (hereinafter called AF) motor 13a. 
FIG. 6 is a cross-sectional view of a camera schematically showing a flash 
modulation system. 
A light beam from the object passes through a photo-taking lens barrel 21 
to a main mirror 22. A part of the light beam passes through the main 
mirror 22, is reflected by a sub-mirror 23 and is directed to a focus 
detecting portion 25 provided at the bottom of the camera 24. The focus 
detecting portion 25 is comprised of a focus detecting optical system and 
the focus detecting circuit 9 which is shown in FIG. 4, and detects the 
focus adjusted state of the photo-taking lens on the basis of the light 
beam from the object. On the other hand, part of the light beam from the 
object which is reflected by the main mirror 22 is observed by the 
photographer through a focusing screen 26, a pentaprism 27 and an eyepiece 
28 and also is directed to a photometry portion 30 through a condenser 
lens 29. The photometry portion 30 is comprised of a photoelectric 
conversion element for dividing the interior of the photographing image 
field into a plurality of photometry areas and metering them and the 
photometry circuit 8 shown in FIG. 4, and outputs the brightness 
information of each photometry area. 
When the shutter is released during flash photographing, the main mirror 22 
and the sub-mirror 23 are retracted out of the photographing optical path 
and the shutter 31 is fully opened. At this time, the light emitted from 
the flash device 2 and reflected by the object, i.e., natural light plus 
reflected light of the flash is directed to film 32 through the 
photo-taking lens barrel 21 and further, some of the light is reflected by 
the surface of the film 32 and is directed to a light modulating portion 
34 through a condenser lens 33. The light modulating portion 34 is 
comprised of the divisional light receiving element 11 and light 
modulation circuit 12 shown in FIG. 5 and described above, and effects the 
flash modulation control of the flash device 2. 
FIGS. 7 and 8 show a control program executed by the control circuit 1. The 
control circuit 1 begins to execute this program when the main switch of a 
camera, not shown, is closed. With reference to these figures, the 
operation of the flash modulation control apparatus will now be described 
with image modes such as a fantasy mode, a wedding mode and a balance 
synchro spot mode taken as examples. 
At a step S1, whether the fantasy mode is selected by the image mode 
selecting circuit 5 is discriminated, and if it is selected, advance is 
made to a step S2. The fantasy mode is a photographing method whereby the 
shutter is released with the photo-taking lens focused on the object and 
exposure is effected for a predetermined time, whereafter the photo-taking 
lens is driven at a high speed and exposure is continued with the 
photo-taking lens brought out of focus. According to this photographing 
method, an image which is out of focus is superposed on an image which is 
in focus, and an object image which is in focus is obtained in the central 
portion of the photographing image field and the defocus amount becomes 
greater toward the marginal portion of the photographing image field and 
therefore, the object image is blurred. That is, the effect of zoom during 
exposure is obtained. Accordingly, when this fantasy mode is selected, the 
main object is considered to be at the center of the photographing image 
field, and at the step S2, the central area of the divisional light 
receiving element 11 shown in FIG. 5 is set as a photometry area. That is, 
a weight of 1.0 is set to the central area and a weight of 0 is set to the 
marginal areas, and weighting is effected to the photometric values of the 
respective areas. If this is done, more proper exposure is obtained for 
the main object lying in the central area than when light modulation is 
effected on the basis of the photometric value of the entire photographing 
image field. Subsequently, at a step S3, a TTL light amount level is set, 
but during the photographing by this fantasy mode, a predetermined 
standard light amount level is adopted and no correction is done. Of 
course, correction may be done in conformity with the photographing 
situation. After the photometry area and TTL light amount level of the 
fantasy mode have been set, advance is made to the step S12 of FIG. 8. 
When the step S1 is negated, advance is made to a step S4, where whether 
the wedding mode is selected is discriminated, and if it is selected, 
advance is made to a step S5. In a wedding or the like, it is often the 
case that objects of high reflectivity such as a gold-leafed folding 
screen and a wedding cake are placed near the main object, and flash is 
intensely reflected by these objects of high reflectivity, and if ordinary 
light modulation is effected, flash is stopped early because the amount of 
reflected light is great. That is, under-exposure is brought about for the 
main object. In order to avoid such an inconvenience, in the wedding mode, 
the predetermined standard TTL light amount level is corrected for 
increase, and flash photographing is effected so that the exposure for the 
main object may become proper. During the photographing by this wedding 
mode, at what position in the photographing image field the main object is 
cannot be specified and therefore, at the step S5, all areas of the 
divisional light receiving element 11 are set as photometry areas, and a 
weight of 1.0 is set therefor and light modulation control is effected. 
Subsequently, at a step S6, the predetermined standard TTL light amount 
level is corrected for plus as described above. After the photometry areas 
and TTL light amount level of the wedding mode have been set, advance is 
made to the step S12 of FIG. 8. 
If the step S4 is negated, advance is made to a step S7, where whether the 
balance synchro spot mode is selected is discriminated, and if it is 
selected, advance is made to a step S8. The balance synchro spot mode is a 
flash photographing method which takes the harmony of the main object and 
the background into account. That is, when the main object is at the 
center of the photographing image field, according to the conventional 
flash photographing method, the main object becomes properly exposed, 
while the background portion the flash does not reach becomes 
under-exposed and thus, there results an unnatural photograph in which 
only the main object is relieved. In order to avoid such an inconvenience, 
in the balance synchro spot mode, light emission is stopped earlier than 
usual and the exposure of the main object is made somewhat under to 
thereby adjust the balance with the background. During the photographing 
by this balance synchro spot mode, at the step S8, a weight of 1.0 is set 
at central area of the photographing image field and a weight of 0 is set 
at the marginal area of the photographing image field, and light 
modulation control is effected. Further, at a step S9, as described above, 
the TTL light amount level is corrected for minus. After the photometry 
area and TTL light amount level of the balance synchro spot mode have been 
set, advance is made to the step S12 of FIG. 8. If the step S7 is negated, 
advance is made to the process routine of other image mode. The 
description of the other image mode is omitted herein. 
At the step S12 of FIG. 8, whether the shutter release button is fully 
pushed is discriminated by means of the switch 4, and if it is fully 
pushed, advance is made to a step S14, and if not so, advance is made to a 
step S13. At the step S13, whether the shutter release button is 
half-pushed is discriminated by means of the switch 3, and if it is 
half-pushed, return is made to the step S12, and if not so, return is made 
to the step S1 of FIG. 7. When at the step S14, the shutter 31 is fully 
opened by the shutter portion 10a with the shutter release, the synchro 
contact Sx is closed to make the flash device 2 start light emission. At 
the subsequent step S15, the divisional light receiving element 11 is 
controlled through the light modulation circuit 12, and the light from the 
object reflected by the surface of the film 32 is metered. At a step S16, 
the photometric output of the divisional light receiving element 11 is 
weighted in each photometry area, and whether the integrated value of the 
sum of the weighted photometric values has reached the TTL light amount 
level set at said step is discriminated, and if it has reached that TTL 
light amount level, advance is made to a step S17, where a light emission 
stopping signal FS is sent from the light modulation circuit 12 to the 
flash device 2 to thereby stop light emission. Thereafter, return is made 
to the step S1 of FIG. 7. 
As described above, provision is made of the divisional light receiving 
element 11 for dividing the object field into a plurality of areas and 
metering the reflected light from the object during flash emission and 
design is made such that weighting is effected in each area of the 
devisional light receiving element 11 in conformity with the selected 
image mode and the light modulation control of the flash device 2 is 
effected on the basis of the photometric value of each weighted photometry 
area and therefore, proper exposure is obtained for the main object during 
flash photographing. 
Design is also made such that an optimal TTL light amount level is set in 
conformity with the selected image mode and the light emission of the 
flash device 2 is stopped when the photometric value of the divisional 
light receiving element 11 reaches this TTL light amount level and 
therefore, proper exposure is likewise obtained for the main object. 
Description will now be made of another embodiment provided with an AF 
response mode in which light modulation control is effected in response to 
an AF device. In this embodiment, the flash modulation control apparatus 
shown in FIG. 4 and the camera shown in FIG. 6 are used with the exception 
that a divisional light receiving element 41 shown in FIG. 9 is used in 
lieu of the divisional light receiving element 11 shown in FIG. 5 and 
therefore, the description of them is omitted. 
FIG. 9 shows the relations between the divisional light receiving element 
41 for dividing the photographing image field into seven areas and 
metering these areas and three focus detection areas 42a-42c in the 
photographing image field. A light receiving element 41a for the central 
area corresponds to the focus detection area 42a, a light receiving 
element 41b corresponds to the focus detection area 42b, and a light 
receiving element 41c corresponds to the focus detection area 42c. During 
the photographing by the AF response mode, weighting is preponderantly 
effected to a photometry area corresponding to that focus detection area 
in which the main object seems to lie, and light modulation control is 
effected on the basis of the weighted photometric value and therefore, 
proper exposure is obtained for the main object. 
FIG. 10 shows a light modulation control program during the AF response 
mode which is executed by the control circuit 1. The operation of the 
present embodiment will hereinafter be described with reference to FIG. 
10. 
At a step S21, whether the AF response mode is selected by the image mode 
selecting circuit 5 is discriminated, and if it is selected, advance is 
made to a step S22, and if not so, advance is made to the process routine 
of other mode. The description of the other mode is omitted. At the step 
S22, whether the shutter release button is half-pushed is discriminated, 
and if it is half-pushed, advance is made to a step S23, and if not so, 
return is made to the step S21. At the step S23, focus detection is 
effected in the focus detection areas 42a, 42b and 42c shown in FIG. 9 by 
the focus detecting circuit 9 and the AF motor driving circuit 13 is 
controlled on the basis of the results of those detections to thereby move 
the photo-taking lens. 
At a step S24, a photometry area and a TTL light amount level are set on 
the basis of the results of the detections. For example, when a defocus 
amount indicative of the closest distance is detected in the area 42a, the 
weight of the area of the light receiving element 41a is set to 1.0 and 
the weights of the other areas are set to 0. Also, when a defocus amount 
indicative of the closest distance is detected in the area 42b, the weight 
of the light receiving element 41b is set to 0.5, the weights of the areas 
of light receiving elements 41d and 41f are set to 0.25 and the weights of 
the other areas are set to 0. Further, when a defocus amount indicative of 
the closest distance is detected in the area 42c, the weight of the area 
of the light receiving element 41c is set to 0.5, the weights of the areas 
of light receiving elements 41e and 41g are set to 0.25 and the weights of 
the other areas are set to 0. A predetermined standard value is adopted as 
the TTL light amount level without correction being effected. 
At a step S25, whether the shutter release button is fully pushed is 
discriminated by means of the switch 4, and if it is fully pushed, advance 
is made to a step S26, and if not so, return is made to the step S21. When 
at the step S26, the shutter 31 is fully opened by the shutter portion 10a 
with shutter release, the synchro contact Sx is closed to thereby make the 
flash device 2 start light emission. At the subsequent step S27, the 
divisional light receiving element 41 is controlled through the light 
modulation circuit 12 and the light from the object reflected by the 
surface of the film 32 is metered. At a step S28, the photometric output 
of the divisional light receiving element 41 is weighted in each 
photometry area, and whether the integrated value of the sum of the 
weighted photometric values has reached a predetermined TTL light amount 
level is discriminated, and if it has reached the predetermined TTL light 
amount level, advance is made to a step S29, where a light emission 
stopping signal FS is sent from the light modulation circuit 12 to the 
flash device 2 to thereby stop light emission. Thereafter, return is made 
to the step S21. 
As described above, design is made such that weighting is effected in each 
area of the divisional light receiving element 41 on the basis of the 
result of the detection by the focus detecting circuit 9 and the light 
modulation control of the flash device 2 is effected on the basis of these 
weighted photometric values and therefore, proper exposure is obtained for 
the main object during flash photographing. 
The number of division of the area of the divisional light receiving 
element for metering the reflected flashlight from the object in each of a 
plurality of divided areas and the dividing method are not restricted to 
the above-described embodiments, but any number of divisions and any 
dividing method may be adopted. The set positions of the focus detection 
areas are neither restricted to the above-described embodiments. 
In the construction of the above-described embodiments, the control circuit 
1 and the light modulation circuit 12 constitute light modulation control 
means 101, 101A, 101B, the image mode selecting circuit 5 constitutes 
photographing mode setting means 102, 102A, the divisional light receiving 
element 11, 41 constitutes divisional photometry means 103, 103A, the 
control circuit 1 constitutes weighting means 104, 104A and optimal light 
amount level setting means 105, and the focus detecting circuit 9 
constitutes focus detecting means 106. 
As described above, according to the present invention, provision is made 
of divisional photometry means for dividing the object field into a 
plurality of areas and metering reflected light from the object during 
flash emission and design is made such that weighting is effected to each 
area of the divisional photometry means in conformity with a selected 
photographing mode and the light modulation control of the flash device is 
effected on the basis of the photometric values of each weighted 
photometry area and therefore, proper exposure is obtained for the main 
object during flash photographing. 
Also, according to the present invention, design is made such that optimal 
TTL light amount levels are set in conformity with selected photographing 
modes and the light emission of the flash device is stopped when the 
photometric value of the photometry means reaches those light amount 
levels and therefore, proper exposure is likewise obtained for the main 
object during flash photographing. 
Further, according to the present invention, design is made such that 
weighting is effected to each area of the divisional photometry means 
during flash photographing on the basis of the result of the focus 
detection by focus detecting means and the light modulation control of the 
flash device is effected on the basis of these weighted photometric values 
and therefore, proper exposure is obtained for the main object during 
flash photographing.