JPH0419722A - Camera with pre-flash ttl light measuring instrument - Google Patents

Abstract

PURPOSE:To know an exposure state which is almost in principal lighting photography by performing real stopping-down operation in sequence operation after a pre-lighting switch is pressed by a pre-view motor under the control of a control circuit, and returning a stop to its open position automatically and then displaying an error based upon proper exposure. CONSTITUTION:When the pre-lighting switch 17 is operated, the preview motor 21 is driven to put a stop-down mechanism 14 in operation and after information showing that a real stop state is entered is obtained from a stop encoder 30, a stroboscopic device 24 is made to emit light. When measured light quantity information of a light measuring circuit 31 which photodetects and outputs light reflected by a subject 26 is received, the pre-view motor 21 is driven again to return the stop to its open position and the error based upon the proper exposure value is calculated from the measured light quantity information; and then the error quantity based upon the proper exposure value is displayed on a pre-flash display part 32 after the measured light quantity information and error quantity are stored in a storage part 19a. Consequently, the real stop pre-lighting TTL light measurement of a single-lens reflex camera which performs open-aperture light measurement is enabled and the exposure accuracy in the principal lighting photography is improved.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention performs preliminary flashing before photographing using a strobe light, performs TTL photometry of the light reflected from the subject, and calculates the error of the measured value from the appropriate exposure value. The present invention relates to a camera having a pre-flash TTL photometry device displayed on an exposure correction display section.

(Prior Art) Many proposals have been made for so-called preliminary flash photometry devices that emit preliminary flash before flash photography to obtain exposure value data in advance.

Among these, the applicant has discovered that when using a conventional preliminary flash metering device to perform a preliminary flash and obtain the amount of received light, and then perform light control, an error occurs in the exposure value, and accurate exposure cannot be achieved during shooting. In order to solve the drawback that in a device that obtains the exposure value in advance at the time of flash emission using the reflection from the shutter curtain, the relationship between the reflection from the shutter curtain and the strobe during the main flash must be clarified, which includes an unstable element. An application has been filed for a preliminary photometric calculation output device (patent application No. 1-164260).
According to this preliminary photometry calculation output device, during dimming, the amount of error due to the time lag from light emission stop control to actual light emission stop can be calculated by an integral comparison circuit or the like, and this data can be reflected in the main light emission.

(Problems to be Solved by the Invention) This preliminary photometry calculation output device is premised on dimming a strobe, and is designed to output the amount of error that occurs during dimming as data. In actual photography, there is a similar demand for a general strobe device to obtain an accurate exposure amount before the main flash without using a dedicated strobe that can be adjusted.

Further, for pre-emission TTL photometry using a real aperture of a single-lens reflex camera that performs aperture photometry, a configuration for providing this preliminary photometry calculation output device has not been shown.

An object of the present invention is to meet the above-mentioned needs, and to solve the above-mentioned problems by storing photometry data from pre-flash and calculating the amount of error from the actual exposure value, regardless of whether a general strobe device or a dedicated strobe device capable of dimming is used. can be displayed on the exposure display section, and in a series of pre-flash operations, the actual aperture is realized by driving a motor, making it possible to perform real-aperture pre-flash TTL metering for single-lens reflex cameras that perform wide-open metering, thereby improving the exposure during main flash shooting. An object of the present invention is to provide a camera having a pre-flash TTL photometry device whose accuracy is dramatically improved.

(Means for Solving the Problems) In order to achieve the above object, a camera according to the present invention includes a pre-emission switch, a preview motor, and an aperture mechanism that narrows down an aperture that is in an open state by driving the preview motor to an actual aperture. a strobe device; a photometry IC that receives reflected light from a subject of the light emitted by the strobe device via a photographic lens system and the real aperture; a photometry circuit that measures the amount of light received by the photometry IC; a pre-flash display section that displays an error from an appropriate value; and when the pre-flash switch is operated, the preview motor is driven to operate the aperture mechanism, and information on the actual aperture is sent from the aperture encoder. After that, when the strobe device is activated to emit light and the photometry circuit that receives and outputs the light reflected from the subject receives measured light amount information, the preview motor is driven again to return the aperture to the open position. and calculating an error from the appropriate exposure value based on the measured light amount information, storing the measured light amount information and the error amount in a storage section, and then displaying the error amount from the appropriate exposure value on the pre-flash display section; The pre-flash TTL photometry device includes a control circuit that calculates the error amount again according to the changed value when the aperture value or film sensitivity setting value is changed, and controls the amount of error to be displayed on the pre-flash display section. are doing.

(Example) Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a photometric optical system of a camera having a pre-flash TTL photometric device according to the present invention.

A sub-mirror 2 is arranged behind a main mirror 1 for guiding light from a subject to a finder.

The main mirror 1 is a half mirror, and the sub mirror 2 is a total reflection mirror.

A photometric condensing lens (3) for passing and condensing the reflected light of the sub-mirror 2 or the reflected light from the film surface is arranged below the main mirror 1.

A half mirror 4 is further provided behind this lens 3. On the back side of the half mirror 4, a photometric IC 5 for performing pre-flash TTL spot photometry according to the present invention is arranged.

This photometric IC 5 is used not only for photometry according to the present invention but also as a photometry element for direct light control.

A photometric IC 6 for spot photometry is further arranged in front of the half mirror 4.

Focusing screen 7 is located above the main mirror 1.
, condenser lens8. A pentagonal roof prism 9 and an eyepiece lens 13 are arranged to constitute a finder optical system.

At the rear upper part of the pentagonal roof prism 9, a photometer C12 for center-weighted average photometry is arranged.

Light generated by pre-emission from an object (not shown) passes through a photographic optical system and a real diaphragm (not shown), and a part of it passes through the main mirror 1 and is totally reflected by the sub-mirror 2.

The light reflected by the sub-mirror 2 is condensed by a photometric condensing lens 3, and is imaged on a photometric IC 5.

The reflected light from the subject is sent to the sub mirror 2. Condensing lens for photometry
3 and photometry IC 5, spot photometry is achieved.

FIG. 2 is a diagram showing an embodiment of a circuit for operating a photometric device according to the present invention.

The system control circuit (CPU+) 18 is a circuit that controls the sequence of the entire camera system, and a control circuit (C
PU2) 19 is a circuit for controlling the pre-flash TTL photometry operation of the present application.

A pre-flash switch 17 for performing pre-flash and obtaining an exposure value after narrowing down the aperture that is on the open side to the actual aperture.
A preview switch 16 for narrowing down the aperture that is on the open side to the actual aperture is connected to the system control circuit 18.
It is connected to the.

The dimming circuit 23 is a circuit that dims the dedicated dimming strobe device 24, and causes the dedicated dimming strobe device 24 to emit light and interrupts the light emission under the control of the control circuit 19.

In addition to the dedicated strobe device 24, a general strobe device 25 can also be connected to the dimming circuit 23, and in such a case, full light emission is performed without dimming.

The preview motor 21 drives the aperture mechanism 14 under the control of the control circuit 19, and the aperture 22 via the aperture ring.
This is to narrow down the aperture from the open position to the actual aperture.

When the aperture is completed and the pre-emission and photometry are completed, the preview motor 21 is driven again to return the aperture 22 to the open position.

When the strobe device 24 or 25 pre-flashes, the light is reflected by the subject 26, passes through the photographing lens 27, the aperture 22 narrowed down to the actual aperture, passes through the photometry optical system explained in FIG. 1, and is sent to the photometry IC. ■Image is formed on 5. The photometric circuit 31 measures the amount of light received by the photometric IC (2) at this time, and transmits the information to the control circuit 19. The photometry circuit 31 is also used for direct light control, center-weighted average photometry, and the like.

The motor 28 is used to raise and lower the mirror and to perform aperture during photographing.

The aperture control device narrows down the aperture to a set aperture value by driving the motor 28.

The winding motor 33 is driven under the control of the control circuit 19 each time a photograph is taken, and winds the film one sheet at a time.

The pre-flash display section 32 is for displaying an error in exposure value based on information from the control circuit 19.

The control circuit 19 controls each of the circuit sections and motors described above based on information from the system control circuit 18 using a motor drive circuit (not shown).

Further, based on the photographing setting conditions (shutter speed, aperture, film sensitivity), the time until proper exposure is achieved is measured based on the measured light amount information from the photometry circuit 31, and a proper exposure completion signal is generated. The time up to generation of this completion signal is controlled as the light emission time (light control time from flashing to cutting off) of the dedicated dimming strobe device, and the flashing time is controlled by the storage unit 19a.
At the same time, even after the strobe light emission is cut off, the amount of received light that is actually input is measured until the shutter is closed, and the error from the proper exposure is calculated. The error and the measured light amount information are stored in the storage section 19a, and the pre-flash display section 32 displays the amount of error in the exposure value.

When the photographer changes the aperture value (or film sensitivity) with reference to the display on the pre-flash display section 32, there is also control to calculate the amount of error from the appropriate exposure again and display it on the pre-flash display section 32. conduct.

When using a general strobe device, the time required to reach proper exposure is measured based on the measured light intensity information from the measurement circuit 31, and a proper exposure completion signal is generated. However, this completion signal is not a dedicated flash control, so It is not used as an optical signal. Subsequently, even after the proper exposure completion signal is generated, the error amount is measured until the shank is closed, the error from the proper exposure is calculated from the measured light amount, the error amount and the measured light amount information are stored in the storage section 19a, and the error is stored in the memory section 19a. It is displayed on the flash display section 32.

The information stored in the storage section 19a is held until the pre-emission switch 17 is turned off.

FIG. 3 is a detailed diagram of the configuration near the diaphragm mechanism.

The preview motor 21 shown in FIG. 2 is controlled to rotate forward, reverse, and stop (brake) by a motor drive circuit 15.

The narrowing down mechanism 14 includes a cam 14a, a preview close switch 14b, a preview close switch 14c, and the like, which are turned on and off in conjunction with the movement of the cam. The on state of the preview close switch 14b corresponds to a position where the aperture is on the open side, and the on state of the preview close switch 14C corresponds to a position where the aperture is closed to the actual aperture.

The OFF state of the preview close switch 14b and the preview close switch 14c corresponds to the narrowed down state.

The output shaft of the motor 21 is decelerated by a gear (not shown) and transmitted to a gear fixed to the cam 14a.

The rotation of the cam is transmitted to the aperture ring by a connecting member (not shown), and the aperture is held at the open position when the preview switch 16 or the pre-emission switch 17 is not turned on.

The rotation of the aperture ring drives the aperture encoder 30, and an aperture pulse is input to the control circuit 19. This aperture pulse informs the control circuit 19 of the aperture value and is used as data for controlling the motor 21 when the aperture mechanism is activated.

When the preview switch 16 or the pre-emission switch 17 is turned on to start the narrowing down operation, the control circuit 19 sends a control signal to the motor drive circuit 1 to reverse the motor 21.
Send on 5th.

In this embodiment, the aperture is narrowed down to the actual aperture depending on the direction of the reverse rotation of the motor.

The cam 14a is initially in the open position, and when it starts rotating, the preview close switch 14a rotates by a predetermined amount.
b turns off, and the aperture ring rotates to start narrowing down the image.

When the cam 14a further rotates, the preview close switch 14c is turned on and reaches the open position. At the same time, the aperture ring also reaches the open position and the motor 21 stops. In the open position, the aperture ring is regulated against its own biasing force, and is released by the rotation of the cam 14a, and reaches the minimum aperture position by the biasing force. This narrows the aperture to the actual aperture.

When the narrowing down is completed and a signal is input from the control circuit 19 to the motor drive circuit 15 to further reverse the motor 21 to return to the original open position, the cam 14a further rotates in the same direction and closes the preview close switch 14b. turns on and reaches the open position from the aperture position (the cam 14a is shaped so that the distance from the center of its outer periphery suddenly increases from the minimum to the maximum).The rotation of the cam 14a causes the aperture ring to return to its original position. is returned to the open position.

FIG. 4 is a flowchart for explaining the sequence when a pre-flash operation is performed by a dedicated strobe device and a general strobe device.

FIG. 4 (al is the case where the light is adjusted by a dedicated strobe device.

When you operate the pre-emission switch and turn it on (step 1),
The control circuit 19 controls the aperture mechanism 14 and sets the aperture to the actual aperture (step 2).

Next, preliminary light emission is performed via the dimming circuit 23, the light reflected from the subject is measured by the photometry circuit 31, and the light emission is stopped based on preset conditions. This dimming time is then stored (step 3) and the actual measured amount of received light is obtained.

Thereafter, the diaphragm is returned to the open position by the aperture control mechanism (step 4), the error from the appropriate value is calculated based on the above-mentioned measured light reception information, and the measured light reception information and the amount of error are stored (step 5).

The amount of exposure error is displayed on the pre-flash display section 32 (step 6).

FIG. 5(a) shows an example of a viewfinder display section.

The shutter speed display section 4 is located at the right end of the finder display section 35.
2, a display section 43 that shows the state of the aperture, including the pre-flash display section, is arranged at the bottom.

FIG. 5(b) shows a further enlarged view of the display section 43.

The pre-flash display section 32 indicates proper exposure when only the central LED 32a is lit.

Two steps of overexposure can be displayed on the right side of this LED 32a. Additionally, two stages of exposure amplifiers can be displayed on the left side. For example, if the aperture is overexposed by one step, the LED elements up to +1 will light up.

Note that if there is an error of two or more steps in both overexposure and up, all two steps are lit.

Furthermore, since the light emitted by this dedicated strobe device is dimmed, the exposure value is theoretically correct and no error occurs, but in reality, errors occur due to time lag and the like. However, the amount of error is extremely small compared to when a general strobe, which will be described later, is used to emit light.

If the photographer changes the aperture value to suit his or her photographic image after checking the amount of exposure error on the pre-flash display section 32, the control circuit 19 adjusts the exposure error again in accordance with the changed aperture value. is calculated, and the pre-flash display section 32
display the amount of exposure error.

After the photographer checks the exposure when firing the main flash in this way, when he releases the camera and turns on the shutter 20 (step 7), the control circuit 19 receives this information via the system control circuit 18 and controls the mirror. actuation, which drives the diaphragm actuation motor 28; As a result, the mirror is raised and the aperture control device 29 is operated to narrow down the image (step 8).

After this, the shutter opens (step 9) and the storage section 19a
The dedicated strobe device 24 emits light for the same time as the dimming time stored in (Step 10). The shutter closes (
When the exposure is completed in step 11), the control circuit 29 controls the motor 28 to lower the mirror and open the aperture (step 12).

Thereafter, the film is wound and the shutter is charged by the winding motor 33 operated by the control circuit 19 (step 13), and the light emission photographing is completed.

Next, a case will be described in which the general strobe device shown in FIG. 4(b) is used.

Operate the pre-emission switch 17 to turn it on (switch 1)
Then, the aperture value is narrowed down to the set actual aperture value in the same manner as explained in FIG. 4(a) (step 2).

Thereafter, the strobe device 25 emits light, and photometry is performed in the same manner as with dedicated strobe light emission. Note that in the case of a general strobe device, light control is not performed, and the amount of light emitted is set on the general strobe device side.

When the photometry is completed, the aperture is returned to the open position (step 4), and the error from the appropriate exposure value is calculated based on the measured light reception information, and the amount of error and the measured light reception information are stored in the storage section 19a (step 5). ).

The amount of exposure error is displayed on the pre-flash display section 32 (step 6).

Based on this amount of exposure error, the photographer can change the aperture to obtain the photographed image of the photographer.

In actual photography using this general strobe device, the sequence is the same as when using a dedicated strobe device, but the general strobe device during actual photography emits light with the same amount of light as the pre-flash.

(Effects of the Invention) As described above, the present invention is applicable to pre-flash TTL metering in which the exposure error from the appropriate exposure value can be known in advance by pre-flashing when photographing with a strobe device, by pressing the pre-flash switch. After that, the preview motor performs the actual narrowing down based on the control of the control circuit.
It is configured to automatically return to the open position and display the error from the proper exposure on the display section.

Therefore, it is possible to realize a pre-flash TTL photometry device using an actual aperture in an aperture metering single-lens reflex camera, and it is possible to know the exposure state very close to the actual flash photography.

The pre-flash TTL photometry device according to the present invention calculates by including not only the error caused by the time lag from the stop of light emission, but also all of the problems in direct photometry, that is, errors caused by photometry distribution, film-specific reflectance errors, and subtle measurement errors of reflected light. Therefore, this is exposure information that is preferable for the photographer when considering the shooting conditions.

In addition, the control circuit stores photometry information and calculates the error from the appropriate exposure value based on the setting conditions, so the photographer can check the exposure display and adjust the aperture or If you change the film sensitivity, you can recalculate and display the exposure error for the changed value.

Furthermore, the control circuit adjusts the brightness for a special strobe and performs photometry after the flash is cut off to obtain actual photometric information, and calculates the error. Since the camera is configured to calculate the error from the correct exposure based on the amount of light and the preview motor performs a series of aperture operations, it is possible to perform pre-flash TTL metering using the actual aperture with both dedicated strobes and general strobe devices. Become.

This pre-flash operation is not based on reflection on the film surface (direct photometry), but instead uses a mirror to reflect the TTL incident light and then measures the reflected light. Therefore, photometry is possible even with very small amounts of light, making it possible to identify the subject. It is also possible to measure only the area (spot photometry).

Furthermore, since the stored value can be maintained until the pre-emission switch is turned off, it is possible to lock the amount of light emission in the case of continuous light emission using a dedicated strobe.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of a photometric lens system of a camera having a pre-flash TTL photometry device according to the present invention;
The figure is a block diagram showing an embodiment of the circuit section of the pre-flash TTL photometry device, FIG. 3 is a detailed diagram of the circuit section of the aperture mechanism section, and 411! 1 is a flowchart for explaining the sequence of pre-flash TTL photometry, and FIG. 5 is a diagram showing an example of a viewfinder display section. 1... Main mirror 2... Sub mirror 3... Condensing lens for photometry ■ 4... Half mirror 5... Photometry IC ■ 6... Photometry IC ■ 7... Focusing screen 8...・Condenser lens 9...Penta roof prism 10...Condensing lens for photometry■ 11...Total reflection mirror 12...Photometry IC■ 13...Eyepiece lens 16...Preview switch 17...Pre Light emitting switch 8...System control circuit 1 (CPU.9...Control circuit (CPU2) O...Shaft...Preview motor 2...Aperture 3...Dimmer circuit 4...Dedicated light control Strobe device 5... General strobe device 6... Subject 7... Lens 8... Mirror operation, aperture operation motor 9... Aperture control device 0... Aperture encoder... Metering circuit 2...・Pre-flash display section 3... Winding motor 5... Viewfinder display section

Claims (1)

[Claims] a pre-flash switch, a preview motor, a diaphragm mechanism that narrows down the aperture that is in an open state due to drive of the preview motor to an actual aperture, a strobe device, and a photographic lens that captures the light reflected from the subject of the light emitted by the strobe device. a photometric IC that receives light through the system and the actual aperture, a photometric circuit that measures the amount of light received by the photometric IC, and a pre-flash display that displays an error from an appropriate exposure value;
When the pre-flash switch is operated, the preview motor is driven to operate the aperture mechanism, and after obtaining information from the aperture encoder that the aperture is set to the actual aperture, the strobe device is activated to emit light reflected from the subject. When receiving the measured light amount information of the photometry circuit that receives and outputs the incoming light, the preview motor is driven again to return the aperture to the open position, and the error from the appropriate exposure value is corrected based on the measured light amount information. After calculating and storing the measured light amount information and the error amount in the storage section, the error amount from the appropriate exposure value is displayed on the pre-flash display section, and when the aperture value or film sensitivity setting value is changed, the error amount is displayed on the pre-flash display section. A camera having a pre-flash TTL photometry device comprising a control circuit that calculates the error amount again according to the value and controls the error amount to be displayed on the pre-flash display section.