JP2590834B2 - Automatic daylight synchronization system for cameras - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic daytime synchro system for a camera capable of automatically performing daytime synchro photography with a camera.

"Conventional technology" Conventionally, this type of technology involves determining the exposure value
Some are determined by metering the stationary light by a centralized metering method such as center-weighted metering, and as an improvement, a predetermined value (for example, 1 EV) is uniformly applied to the exposure value simply calculated from the metering value. Techniques such as addition are also in practical use.

“Problems to be Solved by the Invention” However, in such a conventional technique, in the former case, when the ratio of the main subject (person, etc.) to the screen increases, the background of the main subject becomes overexposed. In the latter case, there is a problem that the background is underexposed if the main subject is not near the center of the screen. Was.

These problems are caused by the fact that the object field cannot be classified because the object field is collectively measured.

Furthermore, regarding the control of the flash light amount, in the daytime synchro photography, since the control is performed by the sum of the stationary light and the flashlight, the classification of the object field is indispensable, and therefore, satisfactory automatic daytime synchro photography cannot be performed. That was the current situation.

The present invention solves these drawbacks, and provides an automatic daylight synchronization system for a camera that can automatically obtain an appropriate steady light exposure and a flash automatically in various scenes in daylight synchronization photography. Aim.

"Means for Solving the Problems" The gist of the present invention for achieving this object is as follows: flash means for emitting flash light; photometric means for dividing an object field into a plurality of areas; Flash control means for stopping emission of the flash means when the sum of the stationary light and the reflected light of the flash light from the subject reaches a predetermined exposure amount; In the automatic daylight synchronization system of a camera which appropriately performs the exposure, a first zone selecting means for determining an exposure value from an average luminance value and a maximum luminance difference and a second zone selecting means for calculating an exposure amount are provided. And an object classifying means for selecting an appropriate zone by each zone selecting means to classify the scene, and based on an output of the object classifying means, the average luminance value is reduced or As the maximum brightness difference decreases, Exposure calculation means for calculating an exposure value with emphasis on a high brightness value among the brightness values of the respective areas, and controlling an exposure comprising a combination of an F number and an exposure time of a shutter based on an output of the exposure calculation means. Exposure control means, and exposure calculation means for calculating, based on the output of the object scene classification means, the predetermined exposure that decreases as the average luminance value decreases. Exists in the camera's automatic daytime synchro system.

[Operation] However, when performing daylight synchro photography, the photo field is divided into a plurality of areas by the photometry means and photometry is performed, and the difference between the average value and the maximum luminance value of the brightness value of each area is obtained by the field classification means. And the parameters are used to classify the object scene, the exposure calculating means calculates an exposure value consisting of a combination of the F-number and the exposure time of the shutter based on the output of the object classifying means, and the exposure control means based on the output. In addition to controlling the exposure, the flash means emits a flash, and the exposure calculated by the exposure calculator based on the output of the object classifying means is compared with the sum of the reflected light from the subject of the steady light and the flash. When it reaches the exposure level, the flash control means stops the emission of the flash means and automatically controls the exposure value and flash amount, so that the proper exposure and flash emission are always maintained in various scenes. line It is something that was to be done.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Each drawing shows an embodiment of the present invention.

As shown in FIG. 2, this embodiment is realized by using a single-lens reflex camera as a medium, and the figure shows a state of the camera during finder observation.

Light flux that has passed through the photographing lens structure 2 (in this case, stationary light)
Is reflected by the mirror 4 of the single-lens reflex camera body 1, passes through the reticle 5 and the pentaprism 6, and is partially guided to the eyepiece 7, and the other is partially focused on the condenser lens 8 and the light receiving element 9.
It is arranged so that it may be led to photometric means consisting of. The photometric means changes the screen (field) to L, C, R, U as shown in FIG.
, And photometry is performed in three areas excluding the U area.

FIG. 4 shows a state in which the camera is performing a photographing operation. The light emitted from the flash device 3 and reflected back to the subject and the stationary light both pass through the photographing lens structure 2 and are reflected by the mirror. Since 4 is retracted, it reaches the film surface 11. Then, the light is reflected by the film surface 11 and
It is configured to be guided to a photometric means for photographing operation, comprising:

FIG. 1 is a block diagram showing a configuration of an automatic daytime synchronization system of a camera. The photometric means logarithmically compresses and opens the light receiving element 9 of FIG. 2 and its three output currents I _L , I _C , I _R (subscripts respectively correspond to the three divided regions L, C, R). Means for correcting the F value and converting it into luminance values B _L , B _C , and B _R are included.

The object field classification means is obtained by the following equations (1) and (2).
First zone selecting means for determining an exposure value described later from the average luminance value A _ve and the maximum luminance difference _され る represented by
Second zone selecting means for calculating the exposure amount.

Δ = MAX (B _L , B _C , B _R ) −MIN (B _L , B _C , B _R ) (2) The exposure calculation means performs the high brightness limit processing on the brightness values B _L , B _C , B _R Then, they are converted into B _L (*), B _C (*), and B _R (*), and then the exposure value is determined. The exposure control means is connected to the means. Here, the exposure value refers to an amount determined by a combination of the F number and the exposure time of the shutter.

The exposure calculating means is connected to the second zone selecting means of the object classifying means and calculates a predetermined exposure, and further connected to a flash control means for controlling the flash means. The flash control means includes a part of the photometering means for the photographing copper action.

The predetermined exposure amount is the sum of the steady light and the flash light, and is a predetermined amount determined to determine the stop of the flash light.

FIG. 5 and FIG. 6 show diagrams of zone selection means for determining an exposure value and a predetermined exposure amount, respectively, using the value of the average luminance value A _{ve and the} maximum luminance difference _{パ ラ メ ー タ} as parameters,
It was determined experimentally.

First, FIG. 5 is a diagram for determining the exposure value.
It is divided into three zones, M (*) and BM (*).

A ₁ and A ₂ and boundary lines n and m in this diagram will be described below.

That, A ₁ is the value of the order of ± 1, based on the 10 (EV), A ₂ is Is a value of about ± 1 on the basis of.

The boundary line n is represented by A _ve = A ₁ , and the boundary line m is
Δ = −k (A _ve = A ₂ ). However, the constant k takes a value of about +1 or -0.5 based on 1.

In the zone N, the average luminance value A _ve is a predetermined value A ₁ (9 to ₁₀ EV (ASA
/ ISO 100)), which is not subject to automatic daylight synchro photography, and is a general flash photography area in dark places such as at night or indoors. The zone BM (*) indicates an area on the right side of the drawing with respect to the boundary line m. When this zone is selected, the exposure value is the average value after the high brightness limit processing, Becomes

The zone BHM (*) indicates an area between the boundary lines n and m. When this zone is selected, the exposure value becomes the maximum luminance value BH (*) after the high luminance limit processing. And the average value of the average value BM (*), Becomes

Next, FIG. 6 is a diagram for determining a predetermined exposure amount, which is divided into five zones of X0, X2, X22 / 3, X31 / 3, and X4.

Shown below A ₃ to A ₅ and △. 1 to △ 4 of this diagram.

The zone X0 is not a target area for daytime synchro photography as in FIG. 5, but a general flash photography area in a dark place such as at night or indoors. A predetermined exposure amount X0 in this zone,
This will be referred to as a standard exposure amount.

Predetermined exposure amounts of zones X2, X2 2/3, X3 1/3, X4 are set to X2, X2
If it is expressed as 2/3, X3 1/3, X4, the subscript is the standard exposure X0
Represents the amount of shift (EV) in the negative direction from.

For example, if X0 = 0.1 [l _{X · S} ], X2 2/3 becomes Becomes

Incidentally, A _n of Figure 5 and Figure 6, △ value of _n varies little with performance of photometric optical system.

 Next, the operation will be described.

In the photometric means, the output currents I _L , I _C ,
I _R is logarithmically compressed and corrected for the open F value to obtain luminance values B _L , B _C , and B _R
And output to the object classifying means.

Then while the luminance value B _L is, B _C, only those which a predetermined luminance value (e.g., 15 2 / 3EV (ASA / ISO 100) or a luminance value of B _R, the luminance value, the predetermined luminance value The high-brightness limit process is performed, and the brightness values after the high-brightness limit process are output to the exposure calculation means as B _L (*), B _C (*), and B _R (*).

The subject field classification means, the brightness value B _L, B _C, the average luminance value A of B _R
ve and the maximum luminance difference Δ are calculated, and an appropriate zone is selected by each zone selecting means.

More specifically, when the camera is pointed at an existing scene, the luminance value measured by the photometric means is B _L = 16 EV (hereinafter all referred to as ASA / ISO 100) B _C = 14 EV, B _R = 15 Suppose it was 1 / 3EV.

From this luminance value, when the average luminance value _Ave and the maximum luminance difference △ are obtained, Δ = 16−14 = 2 [EV]. this Assuming that the value of Δ = 2 corresponds to the point C in FIGS. 5 and 6, the exposure value is selected as the zone BM (*) and the predetermined exposure amount is selected as the zone X22 / 3.

If the limit value of the high brightness limit processing is 15 2/3,
B _L = 15 2 / 3EV B _C = 14EV B _R = 15 1 / 3EV, so the exposure value is Becomes The exposure calculation means sets, for example, the F-number as the exposure value, the shutter exposure time to 1/125 [S] (supposed to be within the speedlight tuning speed), and outputs the exposure value to the exposure control means.

Further, the exposure amount calculating means, a predetermined amount of exposure, when the reference exposure amount and _{X0 = 0.1 [l X · S} ], is set to ^{_{X2 = X 0 · 2 -2 =}} 0.025 [l X · S].

Next, when the release is performed in this state, the F-number becomes 16
Then, exposure is performed at an exposure time of the shutter of 1/125 [S], and light emission is started by the flash means with the shutter fully opened. Then, the exposure amount (the sum of the stationary light and the flash light) measured by the photometry means of the flash control means is 0.025 [l
_{X · S} ], the light emission is stopped. Then, the photographing is completed when the shutter is closed.

In daylight synchro photography, it is necessary to match the exposure determined by the shutter speed and the aperture value with the background of the main subject. Therefore, in the case of daylight synchro photography, in general, if exposure is determined by average photometry (BM (*) in this embodiment), good results can be obtained with high probability.

However, in the direction in which the average luminance value _Ave and the maximum luminance difference △ become smaller, the background tends to be overexposed. Therefore, in this embodiment, the exposure determination (BHM (*))It is carried out.

In this embodiment, the screen is as shown in FIG.
Although it was divided into four regions of L, C, R, and U, the number of divisions is not limited to four. For example, even if it is two, three, five, or more, there is no problem at all. .

Furthermore, the explanation has been given by taking an example of a single-lens reflex camera with a TTL light control method, but this is not limited to a single-lens reflex camera with a TTL light control method. It goes without saying that the same applies to a lens shutter camera.

[Effects of the Invention] According to the automatic daylight synchronization system of the camera according to the present invention, in the case where daylight synchronized shooting is automatically performed by the camera, the object scene is divided into a plurality of areas and photometry is performed. Exposure value and flash intensity are controlled automatically by an algorithm that uses the average and maximum brightness difference of the brightness values of the parameters as parameters. It is possible to do.

[Brief description of the drawings]

Each drawing shows an embodiment of the present invention. FIG. 1 is a block diagram showing a configuration of an automatic daytime synchronization system of a camera.
The figure is a cross-sectional view of the camera equipped with the camera's automatic daylight synchronization system during viewfinder observation. Fig. 3 is an example of a divided screen. Fig. 4 is the photographing operation of the camera equipped with the camera's automatic daylight synchronization system. FIG. 5 is a zone selection diagram for determining an exposure value, and FIG. 6 is a zone selection diagram for determining a predetermined exposure amount. DESCRIPTION OF SYMBOLS 1 ... Single-lens reflex camera main body, 2 ... Lens structure 3 ... Flash device 4, Mirror 6 ... Pentagon prism 8 ... Condensing lens (light measuring means) 9 ... Light receiving element (light measuring means) 12 ... Condensing lens (photometric means provided in flash control means) 13 ... Light receiving element (photometric means provided in flash control means)

Claims (1)

(57) [Claims] A flash unit for emitting a flash; a photometric unit for dividing an object field into a plurality of areas for photometry; and a sum of a stationary light and a reflected light of the flash of the flash from a subject is a predetermined exposure. A flash control means for stopping light emission of the flash means when the amount has reached, and an automatic daylight synchronization system of a camera which cooperates with the flash means and appropriately performs daytime shooting. A first zone selecting means for determining an exposure value from the image data and a second zone selecting means for calculating an exposure amount, and each of the zone selecting means selects an appropriate zone to classify an object field. Field classifying means, based on an output of the field classifying means, places importance on a higher luminance value among the luminance values of the respective areas as the average luminance value decreases or the maximum luminance difference decreases. Exposure calculation to calculate the exposure value A step, exposure control means for controlling an exposure composed of a combination of an F number and an exposure time of a shutter based on an output of the exposure calculation means, and an average luminance value based on an output of the object classifying means. An automatic daytime synchronization system for a camera, comprising: an exposure amount calculating unit that calculates the predetermined exposure amount that decreases as the distance decreases.