JP3327746B2 - Flash photography device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash photographing apparatus capable of controlling a flash.

[0002]

2. Description of the Related Art In a flash light emitting device capable of controlling the amount of light emission, when the amount of light emitted from the flash is extremely small, there are disadvantages that irradiation unevenness is generated on a subject and the amount of light emission is not stable.

The causes of the above-mentioned irradiation unevenness are described below.

When the amount of light emission is extremely small, the discharge arc in the flash discharge tube does not spread all over the tube but is smaller than the inner diameter of the tube. In such a state, the position of the arc is not stable, so that the irradiation characteristics cannot be stabilized, and there is a defect that irradiation becomes uneven.

Next, the reason why the light emission amount is not stable will be described below.

As described above, when the light emission amount is extremely small, the arc of the discharge in the discharge tube is not stabilized, and the flash light applied to the subject is not stabilized.

Conventionally, when the amount of light emission is small and irradiation unevenness or a state in which light emission is unstable may occur, the irradiation unevenness or the state in which light emission is not stable cannot be set in an area where the state occurs. Alternatively, the unstable light emission amount was prevented.

In the above description, a flash device having a general flash control method has been described. However, a flash device of a so-called flat light emission system for controlling the peak value of a flash has the same disadvantage. The reason is described below.

In the flat light emission, generally, a discharge current flowing through a flash discharge tube is periodically controlled at a high speed to stabilize a peak value of light. When the peak value of the light is low, the control current becomes small. At this time, as in the above-mentioned general flash control method, the arc becomes thin, and irradiation unevenness and peak value instability occur.

Conventionally, as in the case of the general flash control described above, when the peak value of the flat light emission is low and there is a possibility that irradiation unevenness may occur, it is necessary to prevent the setting in an area where the irradiation unevenness occurs. This prevents irradiation unevenness or peak value instability.

[0011]

However, the above conventional example has a disadvantage that the control range of the light emission amount and the peak value of the flat light emission in the general flash control method becomes narrow.
An object of the present invention is to prevent the above drawbacks.

[0012]

According to the present invention, a flash device is provided with an automatic irradiation angle control device, and the light emission amount or peak value is set in an area where irradiation unevenness, light emission amount or peak value instability may occur. When the flash angle is changed, the irradiation angle shifts to the wide side, and the light emitted from the flash discharge tube is emitted according to the irradiation angle after the shift.
The above determination is prevented by calculating the light amount or the peak value and increasing the light emission amount or the peak value.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A flash photographing apparatus according to the present invention is a flash photographing apparatus capable of automatically changing an irradiation angle according to a focal length of a photographing lens. Setting means for setting a light output value; calculating means for calculating a light output value from the flash discharge tube based on the light output value set by the setting means and information corresponding to the irradiation angle; and Control means for controlling a light output value from the flash discharge tube based on the light, a comparison means for comparing the calculated light output value from the discharge tube with a predetermined value,
If the light output calculated by the comparing means is lower than a predetermined value, the irradiation angle is shifted to the wide side , and the illumination after the shift is changed.
Based on the firing angle, the calculating means
The light output value is calculated. Having the above configuration
As a result, the light output value increases.

With the above arrangement, the light output value from the flash discharge tube is calculated, and the calculated light output value is compared with a predetermined light output value set for the subject. The light output value from the flash discharge tube can be controlled. Further, the control range of the light emission amount and the peak value of the flat light emission in the general flash control method can be widened.

According to a second aspect of the present invention, when the light output calculated by the comparing means is lower than a predetermined value, and when the irradiation angle is shifted to the wide side, the light is output based on the irradiation angle after the shift. The calculation means calculates a light output value from the flash discharge tube. With the above configuration, the light output value can be determined.

Further, the light output value for the subject is a light emission amount. With the above structure, the amount of light emission can be determined.

Further, the light output to the object is a peak value of light. With the above structure, the emission value can be determined.

Further, the calculation is performed in accordance with a table in which a coefficient corresponding to the focal length of the photographing lens is specified. With the above configuration, the calculation can be performed easily and accurately.

Further, when the light angle calculated by the comparing means is lower than a predetermined value when the irradiation angle is also at the widest position in accordance with the focal length of the photographing lens as described in claim 6, the light angle is smaller than the predetermined value. The irradiation angle is prohibited from shifting to the wide side. With the above structure, irradiation unevenness can be prevented.

[0020]

FIG. 1 shows an embodiment of the present invention. 1 and 3
FIG. 3 is a diagram that best illustrates the features of the present invention.

In FIG. 1, reference numeral 1 denotes a power supply battery which supplies power to a plurality of circuits described later. Reference numeral 2 denotes a booster circuit for charging a later-described main capacitor 3 to a high voltage. The booster circuit has a control terminal connected to a port P6 of the microcomputer 20 described later. Reference numerals 3 and 4 are resistors connected in series, and the series circuit is connected in parallel to a main capacitor 5 described later. Reference numeral 5 denotes a main capacitor, which discharges electric charges stored in the capacitor 5 through a flash discharge tube 14 described later to emit flash light. Reference numeral 6 denotes a light receiving element, whose cathode is connected to an output of a stabilizing power supply (not shown), and directly detects light emission of a flash discharge tube 14 described later via a glass fiber 21. A resistor 7 has one end connected to the anode of the light receiving element 6 and the other end connected to the negative pole of the main capacitor 5. Reference numeral 8 denotes a comparator having a hysteresis characteristic. A negative input is connected to a connection point between the light receiving element 6 and the resistor 7, and a positive input is connected to the port 2 of the microcomputer 20. An AND circuit 10 has one end connected to the output of the comparator 8 and the other input connected to a port 3 of a microcomputer 20 described later. The output is connected to the gate of the IGBT 12 described later. Reference numeral 9 denotes a trigger circuit. The input is a port P1 of the microcomputer 20.
The output is connected to a trigger electrode of the flash discharge tube 14. Reference numeral 14 denotes a flash discharge tube which emits light by discharging the charge stored in the main capacitor 5, and has a cathode connected to an IGBT.
The anode 12 is connected to one end of a coil 13 described later. Reference numeral 13 denotes a coil for controlling the discharge current, one end of which is connected to the main capacitor 5 and the other end of which is connected to the anode of the flash discharge tube 14. 15 is a diode,
The cathode is the main capacitor 5 and the anode is the flash discharge tube 1.
4 is connected to the cathode. Reference numeral 16 denotes a resistor, one end of which is connected to the port P5 of the microcomputer 20, and the other end of which is a
17 are connected to the anode. Reference numeral 17 denotes an LED that indicates the state of charge of the main capacitor 5, and the cathode is connected to the negative terminal of the power battery 1. Reference numeral 18 denotes a switch operated by the photographer. One end is connected to the port P4 of the microcomputer 20, and the other end is connected to the minus terminal of the power battery 1. The switch 18 is turned on when the flash device is used, and turned off when not used. Reference numeral 20 denotes a microcomputer (microcomputer). Reference numeral 19 denotes a light emitting unit position control unit including a motor control circuit, which is connected to the microcomputer 20 via a line group L1. The microcomputer 20 is connected to a camera microcomputer (not shown) and a line group L2.
Connected through.

Next, the operation of FIG. 1 will be described below.

The microcomputer 20 is configured to always receive power from the power battery 1. Switch 1
When the microcomputer 8 is turned on, the state is detected by the microcomputer 20, the port P6 of the microcomputer 20 becomes high level, and the booster circuit 2 starts operating. The operation of the booster circuit 2 charges the main capacitor 5. The charging voltage is the resistance 3 and 4
Is transmitted to the port P7 of the microcomputer 20 via an A / D converter, and is transmitted to an A / D converter inside the microcomputer 20 to perform voltage detection. As a result, when the voltage reaches a predetermined value at which flash photography is possible, the port 5 is set to a high level, and the LED 17 is turned on. When the focal length information of the photographic lens (not shown) is received from the camera via the line group L2, the light emitting unit position control means 19 changes the light emitting unit position from a Fresnel lens provided on the front surface of the light emitting unit to a predetermined value corresponding to the lens focal length. Move to the positional relationship. When the microcomputer 20 inputs the peak value information for the subject from the camera via the line group L2,
The coefficient corresponding to the focal length is derived from a table provided in the microcomputer 20, and the crest value information is multiplied by the coefficient and the constant to determine the crest value of the discharge tube that the discharge tube must actually control, and the discharge is determined. An analog voltage corresponding to the tube peak value is output to port P2.

Next, when a light emission start signal is input from the camera, the ports P1 and P3 of the microcomputer 20 are set to a high level. The high level of the port P3 is the AND circuit 10
And the voltage of the resistor 7 of the light receiving element 6 is 0 because the discharge tube 14 does not emit light.
Therefore, the output of the comparator 8 is at a high level, and the high level changes the output of the AND circuit 10 to a high level, and the IGBT 12 is turned on. The high-level signal of the port P1 is transmitted to the trigger circuit 9, and the trigger circuit 9 generates a high-frequency high voltage at the output, and
Since the discharge tube 14 is ionized and the IGBT 12 is turned on as described above, the electric charge charged in the main capacitor 5 is discharged through the coil 13, the discharge tube 14 and the IGBT 12, and The tube 14 starts emitting light.

The light emitted from the discharge tube 14 is guided to the light receiving element 6 through the fiber 21, and a photocurrent starts flowing through the light receiving element 6. The photocurrent causes a voltage 6 proportional to the light intensity to be applied to the resistor 7.
The photocurrent starts to flow through. The photocurrent generates a voltage in the resistor 7 in proportion to the light intensity. The voltage is the comparator 8
Exceeds the plus input voltage of the D / A converter from the microcomputer 20, ie, the voltage of the output port P2 of the D / A converter.
Changes to low level and is applied to the input of the AND circuit 10, and the output of the AND circuit 10 becomes low level.
The low level is applied to the gate of IGBT 12 and
GBT 12 is turned off. With this off, the coil 13
Is discharged through the discharge tube 14 and the diode 15. Therefore, even when the IGBT 12 is turned off, the light emission does not stop in synchronization with the off, but attenuates in response to the energy release of the coil 13. When the voltage of the resistor 7 drops to a voltage lower than the plus input voltage of the comparator 8 by a predetermined value due to the attenuation, the output of the comparator 8 changes to a high level and is transmitted to the input of the AND circuit 10,
The output of the AND circuit 10 becomes high level. The high level is applied to the gate of the IGBT 12, and the IGBT 12 is turned on. By this turning on, the electric charge from the main capacitor 5 is discharged again through the coil 13 and the discharge tube 14, and the light emission output increases. Thereafter, the above-described operation is repeated, and the light emission output becomes almost until the port P3 becomes low level. It is controlled to be constant.

Table 1 shows one embodiment of the table. The table is described in detail below.

The relationship between the light emitting portion position information (s), the coefficient (n), and the light emission output (guide number) with respect to the focal length (f) of the lens is shown. The table in the microcomputer 20 stores light emitting unit position information (s) with respect to the focal length of the lens.
And the coefficient (n) are set.

The light emitting unit position information (s) is determined based on the focal length information (f) from the lens, and as shown in Table 1, for a focal length of 24 mm, each focal length is 1 as shown in Table 1. Are defined as integer values from 0 to 7. The light emitting unit position control is performed based on the integer value.
As shown in Table 1, for example, the position of the integer light emitting unit with respect to the light emitting unit information 1 is controlled by the light emitting unit position control circuit so as to obtain irradiation characteristics covering the angle of view of the lens having a focal length of 24 mm.

The coefficient is a coefficient for obtaining a discharge tube peak value that is multiplied by the output peak value from the camera, and varies depending on the focal length of the lens. As shown in Table 1, for example, the coefficient for a focal length of 24 mm is 1. The coefficient is determined to be 1 when the light emitting unit position information is 1 (24 mm cover), and the coefficient (n) for the focal length of the lens to be used is:
This is a value obtained by squaring a value obtained by dividing the guide number 24 by the guide number at the light emitting unit position with respect to the focal length of the lens.

Next, parts related to the present invention will be described in detail with reference to the flowchart of FIG. Hereinafter, each step is abbreviated as S.

A power supply battery is loaded into the flash device, and the microcomputer 2
0 is in the initialized state. At this time, all the output ports are at the low level, and only the input port P4 is in the detectable state (S1). Next, the state of the port 4 is determined. When the switch 18 is at the low level, that is, when the switch 18 is on, the process proceeds to S3, and when the switch 18 is off, the process returns to S2 (S2). Thereafter, all the input ports are in a detectable state, and the port P6
To a high level to operate the booster circuit 2 and start charging the main capacitor 5 (S3). Then, an output peak value h is input from a camera (not shown) via the port group 2 (S
4). Further, focal length information f of the photographing lens is input from the camera (S5). Then, light emitting unit position information s corresponding to the focal length information is obtained from the table (S
6). Next, a coefficient n corresponding to the light emitting unit position information is obtained from the table (S7). Thereafter, the output peak value h is multiplied by the coefficient n and the constant K to calculate a discharge tube peak value H (S8).

Next, the discharge tube peak value H is the minimum discharge tube peak value Hmin at which irradiation unevenness or emission stability can be tolerated.
It is determined whether or not it is above (S9), and if it is above, the process proceeds to S10,
If smaller, go to S19. Then, the discharge tube peak value H is H
If it is not shorter than min, the light emitting unit position is controlled by the light emitting unit position control circuit in accordance with the light emitting unit position information (S1).
0). Next, an analog voltage value corresponding to the discharge tube peak value H is output to the port P2 by the D / A converter inside the microcomputer 20 (S11). Thereafter, the voltage of the port P7 is detected (S12). When the voltage is equal to or more than the predetermined value, it is considered that the charging of the main capacitor 5 is completed, and the process proceeds to S13. If the predetermined value has not been reached, it is considered that charging has not been completed, and S
Return to 12. When the charging is completed, the port P5 is set to the high level (S13). The LED 17 indicating the completion of charging of the main capacitor at the high level lights up. In S14, a charge completion signal is output to a camera (not shown) via the port group L2, and the mode of the camera is set to a mode suitable for flash photography. In S15, a light emission start signal is input from the camera. In S16, the port P1 and the port P
3 is set to the high level. Light emission is started by the high level as described above. Then, a light emission stop signal is input from the camera (S17). Then, the port P1 and the port P3 are set to the low level. Due to the low level, light emission is stopped as described above (S18).

If the discharge tube peak value H is smaller than Hmin in S9, 1 is subtracted from the value of the light emitting unit position information (S9).
19). Then, it is determined whether the light emitting unit position information value calculated in S19 is greater than 1 (S20).
The process proceeds to S1, and if it is 1 or less, the process proceeds to S22. Then, a coefficient corresponding to the light emitting unit position information value calculated in S19 is obtained from the table (S21). If the light emitting unit position information is 1 or less, the light emitting unit position information is set to 1 (S2
2). Further, a discharge tube peak value is calculated by multiplying the output peak value obtained in S4 by the constant and 1 (S23).

As described above, the light output value (output peak value in the embodiment) is input from the camera which is a means for setting a predetermined value of light output to the subject in S4, and in S8,
The light output from the flash discharge tube (the peak value of the discharge tube in the embodiment) is calculated from the light output value set by the setting means and the information corresponding to the irradiation angle, and the light output from the flash discharge tube is calculated in S9. In step S19, 1 is subtracted from the light emitting unit position information in comparison with a predetermined value (Hmin in the embodiment) in which irradiation unevenness or light emission stability can be tolerated. That is, the light emitting unit position information is shifted to the shorter focal length side, that is, the wide side, and the light emitting unit position is controlled based on the shifted light emitting unit position information in S10.

As described above, even when the light emission output to the object is small, a stable light emission value without irradiation unevenness can be obtained.

FIG. 3 shows another embodiment. The description of the components denoted by the same reference numerals as those in FIG. 1 is omitted.

In FIG. 3, reference numeral 25 denotes an integrating capacitor, one end of which is connected to the anode of the light receiving element 6 and the other end of which is connected to the negative pole of the power battery 1. The connection point with the light receiving element 6 is connected to the minus input of the comparator 8. Reference numeral 22 denotes an NPN transistor. The collector is connected to the negative input of the comparator 8, the emitter is connected to the negative pole of the power supply battery 1, and the base is connected to one end of the resistor 23. 23 is a resistor. 24 is an inverter,
The input is connected to the port P3 of the microcomputer 20 and the output is connected to one end of the resistor 23.

Next, the operation of FIG. 3 will be described. The microcomputer 20 is configured so that power can always be supplied from the power battery 1. When the switch 18 is turned on, the state is detected by the microcomputer 20, the port P6 of the microcomputer 20 becomes high level, and the booster circuit 2 starts operating. The operation of the booster circuit 2 charges the main capacitor 5. The charging voltage is supplied to the microcomputer 20 via the resistors 3 and 4.
Is transmitted to the port P7 of the microcomputer 20, and is transmitted to the internal A / D converter of the microcomputer 20 to perform voltage detection. As a result, when the voltage reaches a predetermined value at which flash photography is possible, the port P5 is set to a high level and the LED 17 is turned on. I do. When the focal length information of the photographic lens (not shown) is received from the camera via the line group L2, the light emitting portion position is controlled by the light emitting portion position control means from a Fresnel lens provided on the front surface of the light emitting portion to a predetermined position corresponding to the lens focal length. Go into a relationship. When the microcomputer 20 inputs the light emission amount information for the subject from the camera, a coefficient corresponding to the focal length is derived from a table provided in the microcomputer 20, and the discharge tube is actually controlled by multiplying the light emission amount information by the coefficient and the constant. A discharge tube light emission amount to be performed is determined, and an analog voltage corresponding to the discharge tube light emission amount is output to the port P2.

Next, when a light emission start signal is input from the camera, the port P3 of the microcomputer 20 is set to a high level.
The high level of the port P3 is given to the inputs of the AND circuit 10 and the inverter 24. The output of the inverter 24 is inverted from the high level to the low level by the change of the input,
The transistor 22 is shifted from ON to OFF. When the transistor 22 is turned off, the integration operation is enabled.
At this time, since the flash discharge tube 14 does not emit light, the voltage of the integrating capacitor 25 is zero. Therefore, the comparator 8
Is at a high level, and a high-level signal is supplied to the port P3 as described above.
Is at a high level, and the IGBT 12 is turned on. Thereafter, the port P1 is set to the high level, and the high level signal is transmitted to the trigger circuit 9. The trigger circuit 9 generates a high-frequency high voltage at the output, is applied to the trigger electrode of the discharge tube 14, and the discharge tube 14 is ionized. Since the IGBT 12 is turned on as described above, the electric charge charged to the main capacitor 5 is discharged from the discharge tube 14 and the IGBT 12
, And the discharge tube 14 starts emitting light.

The light emitted from the discharge tube 14 is directly guided to the light receiving element 6 via the fiber 21, and the photocurrent starts to flow through the light receiving element 6. The photocurrent is integrated by the integration capacitor 25. When the integrated voltage exceeds the plus input voltage of the comparator 8, that is, the voltage of the output port P2 of the A / D converter from the microcomputer 20, the output of the comparator 8 changes to low level and is applied to the input of the AND circuit 10, and Circuit 10
Is at a low level. The low level is IGBT1
2 and the IGBT 12 is turned off. Since the discharge current is cut off by this turning off, the flash discharge tube 14 is turned off.
Stops emitting light. Thereafter, the port P3 is set to the low level, and the output of the AND circuit 10 is set to the low level regardless of the state of the output of the comparator 8. At the same time, the transistor 22 is turned on by the low level of the port P3, and the integration operation ends. Port P at the same time as P3 low level
1 is set to low level to inhibit the operation of the trigger circuit.

Next, parts related to the present invention will be described in detail with reference to the flowchart of FIG. In the following, each step is described as S
Abbreviated.

A flash device is loaded with a power supply battery and the microcomputer 20
Are initialized, and at this time, all the output ports are at a low level, and only the input port P4 is in a detectable state (S101). Next, the state of the port 4 is determined.
And returns to S102 when in the off state (S10
2). After that, all input ports are in detectable state,
The port P6 is set to the high level to operate the booster circuit 2 to start charging the main capacitor 5 (S103). Then, an output light emission amount i is input from a camera (not shown) via the port group 2 (S104). Further, focal length information f of the photographing lens is input from the camera (S105). And
Light emitting unit position information s corresponding to the focal length information is obtained from a table (S106). Next, a coefficient n corresponding to the light emitting unit position information is obtained from the table (S107). Thereafter, the output light emission amount i is multiplied by the coefficient n and the constant K to calculate a discharge tube light emission amount I (S108).

Next, the discharge tube light emission amount I is the minimum discharge tube light emission amount Imin at which irradiation unevenness or light emission stability can be tolerated.
It is determined whether or not the above is the case (S109). If it is the above, the process proceeds to S110. If the discharge tube light emission amount I is equal to or more than Imin, the light emitting unit position is controlled by the light emitting unit position control means in accordance with the light emitting unit position information (S110). Next, an analog voltage value corresponding to the discharge tube light emission amount I is output to the port P2 by the D / A converter inside the microcomputer 20 (S111). After that, port P
7 is detected (S112). When the voltage is equal to or more than the predetermined value, it is considered that the charging of the main capacitor 5 is completed, and the process proceeds to S113. If the predetermined value has not been reached, it is considered that charging has not been completed, and the process returns to S112. The port P5 is set to the high level, and the LED 17 indicating that the charging of the main capacitor is completed at the high level is turned on (S113). In S114, a charge completion signal is output to a camera (not shown) via the port group L2, and the mode of the camera is set to a mode suitable for flash photography. In S115, a light emission start signal is input from the camera. In S116, the port P3 is set to the high level.
The integration operation is started by the high level as described above.
In S117, the port P1 is set to the high level. The light emission of the flash discharge tube 14 is started by the high level. S11
At 8, the ports P3 and P1 are set to low level. The integration operation is stopped by the low level of the port P3 as described above. The trigger circuit is inhibited by the low level of the port P1.

In step S109, the light emission amount of the discharge tube is Imin.
If it is smaller, 1 is subtracted from the value of the light emitting unit position information (S119). Then, it is determined whether the light emitting unit position information value calculated in S119 is larger than 1 (S120). If it is larger, the process proceeds to S121, and if it is 1 or less, S122.
Proceed to. Then, a coefficient corresponding to the light emitting unit position information value calculated in S119 is obtained from the table (S12).
1). If the light emitting unit position information is 1 or less, the light emitting unit position information is set to 1 (S122). Further, the output light emission amount obtained in S104 is multiplied by the constant and 1 to calculate the discharge tube light emission amount (S123).

As described above, in step S104, the light output value (output light emission amount in the embodiment) is input from the camera, which is the means for setting a predetermined value of light output to the subject, and the setting is made in step S108 by the setting means. The light output from the flash discharge tube (in this embodiment, the light emission amount of the discharge tube) is calculated based on the obtained light output value and the information corresponding to the irradiation angle. Is compared with an allowable predetermined value (Imin in the embodiment).
At 119, 1 is subtracted from the light emitting unit position information. That is, the light emitting unit position information is shifted to the short focal length side, that is, the wide side, and the light emitting unit position is controlled based on the shifted light emitting unit position information in S110. As described above, even when the light emission amount for the subject is small, a stable light emission value without irradiation unevenness can be obtained.

In the embodiment of the present invention, the flash device and the camera are separately provided, but it goes without saying that the present invention can be applied to a so-called flash device built-in camera in which the flash device is incorporated in the camera.

[0047]

Correspondence between the invention and the embodiments In the above embodiments, the output light emission amount and the output peak value correspond to the light output of the present invention. The camera corresponds to the setting means for setting the light output of the present invention. In FIG. 1, a circuit including the light receiving element 6, the resistor 7, the comparator 8, the trigger circuit 9, the AND circuit 10, the IGBT 12, and the like corresponds to a control unit for controlling the optical output of the present invention. In FIG. 2, the light receiving element 6, the comparator 8,
A circuit including the trigger circuit 9, the AND circuit 10, the IGBT 12, the integration capacitor 25, the inverter 24, and the like corresponds to a control unit for controlling the light output of the present invention. The microcomputer 20 corresponds to the calculating means and the comparing means of the present invention. Table 1
Corresponds to the table of the present invention.

Further, S20, S22, S1 in FIG.
0, and S120, S12 in FIG.
2. The processing in S110, according to the focal length of the taking lens in the present invention, when the irradiation angle is on the widest side of the variable range, when the light output calculated by the comparing means is lower than a predetermined value, the irradiation angle is smaller. This corresponds to processing for prohibiting shifting to the wide side.

[0049]

[Table 1]

[0050]

According to the flash photographing apparatus according to the first, second and third aspects of the present invention, the light output from the flash discharge tube is calculated, and the calculated light output and the setting for the subject are set. The light output from the flash discharge tube is controlled by comparing the obtained light output with a predetermined value, and the light emission amount or the peak value is set in an area where irradiation unevenness, the light emission amount or the peak value instability may occur. In this case, the irradiation angle is shifted to the wide side, and the light output amount or the peak value of the light emitted from the flash discharge tube is increased, so that the control range of the light output value with respect to the subject can be widened.

[0051]

[0052]

According to the flash photographing apparatus of the fourth aspect of the present invention, the coefficient corresponding to the focal length of the photographing lens is obtained from the table in the microcomputer. it can.

According to the flash photographing apparatus of the fifth aspect of the present invention, when the irradiation angle is at the widest side of the variable range according to the focal length of the photographing lens, the light output calculated by the comparing means is reduced. When the irradiation angle is lower than the predetermined value, the irradiation angle is configured to prohibit the transition to the wide side, so that a mechanism for forcibly prohibiting the transition becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is a block diagram of a flash photographing apparatus showing one embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of FIG.

FIG. 3 is a block diagram of a flash photographing apparatus showing another embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of FIG.

[Explanation of symbols]

 Reference Signs List 1 power supply battery 2 booster circuit 3, 4, 7, 16 resistor 5 main capacitor 6 light receiving element 8 comparator 9 trigger circuit 10 AND circuit 12 IGBT 13 coil 14 flash discharge tube 15 diode 17 LED 18 switch 19 light emitting unit position control means 20 microcomputer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03B 15/04-15/05 G03B 7/16

Claims (5)

(57) [Claims] 1. A flash photographing apparatus capable of automatically changing an irradiation angle according to a focal length of a photographing lens, comprising: setting means for setting a light output value for a subject; and light set by the setting means. Calculating means for calculating a light output value from the flash discharge tube based on an output value and information corresponding to the irradiation angle; control means for controlling a light output value from the flash discharge tube based on the calculation result; Comparing means for comparing the calculated light output value from the discharge tube with a predetermined value; and when the light output value calculated by the comparison result by the comparing means is lower than a predetermined value, shifting the irradiation angle to the wide side. Let
At the same time, based on the irradiation angle after the shift,
The light output value from the flash discharge tube is recalculated to increase the value . 2. The light output value for the object is a light emission amount.
2. A flash photographing apparatus according to claim 1, wherein: 3. The light output to the object is a peak value of light.
Flash photographing apparatus according to claim 1, characterized in that. 4. The operation corresponds to a focal length of a photographing lens.
To perform according to the specified table
The flash photographing apparatus according to any one of claims 1, 2, 3 and 3, wherein: 5. An irradiation angle according to a focal length of a photographing lens.
When on the widest side of the variable range, the comparison means
If the calculated light output is lower than the predetermined value,
5. The flash photographing apparatus according to claim 1, wherein the irradiation angle is prohibited from shifting to the wide side .