JPS61269130A - Device for controlling emission of stroboscopic emission of camera - Google Patents

Abstract

PURPOSE:To make possible an exact emission timing by shifting an emission timing value in the direction where the sensitivity of a film changes according to the difference of a full aperture value when a focal length is changed over. CONSTITUTION:A table which determines the relation between a measured distance value and the emission timing value of a stroboscopic emission for each sensitivity of the film is preliminarily stored in a variable focus camera of which the full aperture value changes. The emission timing value is shifted in the direction where the film sensitivity changes according to the difference of the full aperture value when the focus is changed over. The emission timing is thereby determined. The adequate emission timing for the other focuses is thus obtainable simply by storing the emission timing table for one focus. The smaller memory capacity is required and the correct exposing is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a strobe light emission control device that accurately controls strobe light emission timing with a small memory capacity in a variable focus camera in which the aperture value changes. .

(Prior Art) A variable focus camera generally changes the focal length f of a photographic lens by moving a lens system, or by inserting and removing an auxiliary lens system as the main lens system moves. On the other hand, as is known in the art, in a lens in which the position of the exit pupil coincides with the principal point, if the diameter of the exit pupil is D, then there is a relationship of D/f=l/F, where F is the open aperture value.

This generally applies to variable focus cameras with a built-in aperture.
The short focal length lens f (W) and the long focal length lens f (T) have different F numbers even if they have the same aperture diameter. In other words, even if exposure is performed under the same shutter conditions, the amount of exposure on the film surface is f (W)
and f (T) are different. Figure 4 illustrates this, and shows that when exposure is performed under the same shutter conditions (exposure time) using an electromagnetic program shutter, the exposure amount on the film surface is different because the F number is different. There is.

In conventional variable-focus cameras, it has been proposed to perform correction by switching the aperture on the front of the AE receiver or switching the filter density in response to changes in the aperture value due to changes in the focal length of the photographic lens. It's here. This made the structure of the camera complicated. In addition, in a variable focus camera that stores the shutter speed relative to the subject brightness and performs AE exposure based on this, f (W
), f (T), or other focal lengths may be stored in memory, and the table may be recalled according to the focal length to perform AE exposure. In the aperture diameter change curve shown in Figure 4, the exposure amount control at the time is as follows:
This can be done by making various changes in the shutter opening process shown in A, and this itself is known.

Even in the case of controlling the exposure amount during flash photography by controlling the light emission start time, it is conceivable to take the same means as described above when applying it to the variable focus camera 1.

However, in a variable focus camera, it is necessary to prepare a table of strobe light emission start times for each focal length, which requires a huge amount of memory capacity.

(Objective and Structure of the Invention) The present invention has been made in view of the above points, and it is possible to use a variable focus camera to accurately control strobe light emission timing without requiring a complicated mechanism or a huge memory capacity. In order to achieve this purpose, a table is stored in advance that defines the relationship between the distance measurement value and the flash firing timing value for each film sensitivity.
Focal length 761. ．． ], J * etti h S l,
□,. 1-8: The device was configured to obtain an accurate light emission timing by shifting the light emission timing value in the direction in which the film sensitivity changes.

(Example) The present invention will be explained below based on the drawings.

FIG. 1 shows a bifocal camera as an example of a variable focus camera, and FIG. 1 (A) shows a state in which the lens barrel 1 is pushed toward the camera side to create a short focus f (W). 1st
Figure (b) shows the lens barrel 1 pulled out from the camera and the long focal point f
(T) is shown, and 2 indicates the film surface. The photographic lens has a main lens system 3 and a removable auxiliary lens system 4. The main lens system 3 is attached to the lens barrel 1, and the lens barrel 1 is inserted into the guide member 5 of the camera body. When pushed in, the auxiliary lens system 4 retreats out of the optical path to form a short focus lens f (W), and when the lens barrel 1 is pulled out from the guide member 5, the auxiliary lens system 4 is located on the optical path. Combined with main lens system 3, long focal length lens f (T
) to form. Further, a shutter device 6 that also serves as an aperture is provided within the main lens system 3. The lens barrel 1 moves back and forth on the optical axis along the guide member 5. The guide member 5 is provided with microswitches s (w) and s ("r).

Micro switch S at short focal length lens f (W) position
(W), the microswitch S (T) is turned on at the long focal length lens f (T) position. The maximum aperture value of the lens is F: 3.3 for the short focal length lens f (W) and F: 5.8 for the long focal length lens f (T), and when expressed in Ev value, there is a difference of I + 1 Ev. .

FIG. 2 shows a block diagram of a variable focus camera to which the strobe light emission control device according to the present invention is applied, where lO is D
A film sensitivity reading circuit reads ISO sensitivity information from a film magazine of X-type film, 11 is a distance measuring unit that outputs information according to the distance from the camera to the subject, and 12 is a microswitch shown in Figure 1 (b). S (
W), a focal length information switch corresponding to 5(T),
Reference numeral 13 denotes a photometry unit consisting of a CdS etc. that outputs object brightness information, and 14 measures the shutter speed and shutter speed from the shutter open command to the shutter shutter close command based on the above-mentioned ISO sensitivity information, object distance information, focal length information, and object brightness information. 15 is an ISO controller configured with a microcomputer that calculates the light emission timing value from the open command to the strobe light emission start command and outputs the shirt shutter close signal and the strobe light emission signal;
16 is a strobe light emitting circuit; and 17 is a shutter driver for driving an electromagnetically driven shutter 18.

The distance from the lens to the subject measured by the distance measuring unit 11 is divided into a plurality of (for example, 15) AF zones. Therefore, the table memory 15 stores in advance a table showing the relationship between each AF zone and the light emission timing value (in milliseconds) for each ISO sensitivity index, as shown in Table 1.

This Table 1 shows the light emission timing values for the f (W) lens, and the EFISO zone in the left column is 1/3E.
The step is for each V (EV is the exposure value). (
The light emission timing values shown in this table are the values created by the controller 14. In other words, as an example, the controller 14 measures the timing from the time when the shirt shirt open signal is issued, and at the timing shown in this table. Another example of issuing a strobe firing command is to install a sensor such as a switch that detects the start of rotation of the shutter blade, and start timing from the signal from this sensor, and then fire the strobe at the evening/time shown in the table below. You may also issue commands.

Now, the film sensitivity reading circuit 10 automatically reads the ISO sensitivity index of the film used, the distance measuring unit 11 measures the subject distance, and the focal length information switch 12 selects the short focus lens f(W) or the long focus lens f. (
T) When the focal length information is output, the controller 14
reads the corresponding light emission timing value from the light emission timing table stored in the table memory 15. For example, when using the short focal length lens f (W),
Using a film with an O sensitivity of 400, select a flash timing value of 15.6 S for a subject at a distance of AF zone 5, and at that timing send a strobe flash signal to the strobe flash circuit 16 to fire the strobe. let

However, when the photographic lens is switched to a long focal length lens f (T) for the same subject, the focal length information switch 12
A signal to that effect is output. The maximum aperture value of the lens is F: 3.3 for the short focal length lens f (W), and F: 5.8 for the long focal length lens f (T)? 'Because there is E
Since the lens becomes darker by V value -t:l-3EV, the controller 14 uses the IS of the light emission timing table in Table 1.
Shift the O sensitivity index 5 steps lower in the EFISO zone. In the example above, the ISO sensitivity index is 125.
Read out the light emission timing value 22.6S corresponding to
At this timing, a strobe light emission signal is sent.

In this way, when switching the photographic lens between the short focus lens f (W) and the long focus f (T), the light emission timing value is shifted in the direction that changes the ISO sensitivity by the difference in the open aperture value. You can get the correct exposure just by

Although the above embodiment describes a camera that can switch between two types of focal lengths, cameras that can switch between two types of focal lengths can also be used with the ISO sensitivity index meter and strobe light emission timing according to changes in the open aperture value. By shifting the value-dependent sensitivity table, it is possible to perform appropriate exposure regardless of changes in the focal length of the photographic lens.

FIG. 3 shows a flowchart of strobe light emission control for a bifocal camera according to the present invention. It starts with the first-stage release switch, which is turned on by operating the first-stage release button, and first, the film is loaded by the film sensitivity reading circuit 10 (see FIG. 2). Load the ISO speed of the film (F-1)
), followed by photometry (F-2) by the photometry unit 13,
Distance measurement (F-3) is performed by the distance measurement unit) 11, and photometry continues until the second-stage release switch is turned on by operating the second-stage release button (F-4, F-5).
When the two-stage release switch is turned on, the lens is electrically driven (F-6), and the electromagnetic shutter is once energized in the closing direction (F-7), and accurately returned to its initial position.

After waiting for a period of time for stabilization (F-8), it is determined whether or not it is in strobe photography mode based on the status of the strobe switch (F-9). Open (F-10), wait for the time TAE determined by the intersection data (F-11)
) Close the shutter (F-12), then wait a short time (F-13) and wind the film (F-13).
13).

However, when it is determined in step (F-9) that the flash photography mode is selected, the focal length information switch 12 ( As a result, if it is a short focal length lens f (W), the controller 14 determines the film ISO sensitivity from the light emission timing table stored in the table memory 15 (F-15). Read out the corresponding light emission timing value based on the AF zone based on the measured distance value (F-17
), and conversely, if the long focal length lens f (T) is selected, the controller 15 selects the EF determined by the difference in the open aperture value between the short focal length lens f (W) and the long focal length lens f (T).
The light emission timing value is shifted by five ISO zone steps in the direction in which the film sensitivity decreases (F-16), and the corresponding light emission timing value TAF is read out.

After that, open the shutter (F-18), wait for the above-mentioned light emission timing value TAF (F-19), and send a light emission signal to the strobe light emission circuit 16 to cause the strobe to emit light (F-2).
0), after the strobe fires, the steps mentioned above (F-12,
F-13, F-14), and in the above example, f
(W) and f (T) open aperture value 1@%EV
, the table is set in steps of 1/3 EV, but the table is not compatible with IS where the table can be shifted like this.
It is appropriate to set the O sensitivity zone and the photometry zone in steps.

(Effects of the Invention) As explained above, one aspect of the present invention is to store in advance a table that defines the relationship between distance measurement values and strobe light emission timing values for each film sensitivity in a variable-focus camera in which the maximum aperture value changes. In addition, when the focus is switched, the light emission timing is determined by shifting the light emission timing value in the direction in which the film sensitivity changes according to the difference in the open aperture value, so the light emission timing table for the l focus is calculated. Just by memorizing it, you can obtain the proper light emission timing for other focal points, and you can achieve proper exposure with small memory capacity.

[Brief explanation of drawings]

Figures 1 (A) and (B) are diagrams showing the short focus and long focus lens positions in a bifocal camera, and Figure 2 is a block diagram of a bifocal camera to which the strobe light emission control device of the present invention is applied. FIG. 3 is a flow chart of strobe light emission control according to the present invention, and FIG. 4 is a diagram showing the difference in exposure amount in a bifocal camera. lO... Film sensitivity reading circuit, 11... Distance measuring unit, 12... Focus information switch, 13... Photometry unit, 14... Controller, 15... Table memory, 16... Strobe Light emitting circuit, 17...Shutter driver, 18...Electromagnetic drive shutter Patent applicant: Roku Konishi Photo Industry Co., Ltd. Agent: Hiroshi Suzuki, male, patent attorney Figure 1 (a) (b)

Claims (1)

[Claims] In a strobe light emission control device for a variable focus camera in which the aperture value changes by changing the focal length, the aperture value is set on a table that defines the shooting distance and strobe light emission timing value in accordance with the film sensitivity value. A strobe light emission control device for a variable focus camera, characterized in that the light emission timing value is shifted in a direction in which film sensitivity changes in accordance with a difference in aperture value.