JP2864551B2 - Auto focus camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus camera capable of controlling a flash dimmer.

[Prior Art] Conventionally, a flash light control device is known to be built in an electronic flash device main body and a flash light control device is built in a camera main body. The dimming range is substantially the entire shooting screen or a relatively wide range including the center of the screen.

[Problems to be Solved by the Invention] In the flash dimmer, the dimming level for determining the timing to stop the flash light emission is based on the light reflected at a certain ratio with respect to a certain light emission amount. Is determined. For example, an object having a certain reflectance (average reflectance) is arranged so as to face a flash device so as to include an area for light control, and flash light is emitted to detect the amount of light reflected from the reflective object. Then, the dimming level is determined based on the relationship between the time and the amount of light such that the reflective object is photographed with proper exposure.

However, in general flash photography, the amount of light reflected from the object scene is not constant, so that depending on the setting of the dimming level, the image may be overexposed or underexposed. Specifically, for the dimming area in the shooting screen,
If the proportion of the objects present at the same distance differs, for example, when using lenses with different focal lengths, or when the number of persons or objects is one or more, the The amount of light reflected from the light controller and incident on the dimmer is different. Therefore, the amount of flash light determined by the amount of light incident on the light control device is different from the natural light, and the exposure often becomes unstable.

In order to solve such a problem, the light control area is made small and spot-shaped, and only a part of the object field is measured (that is, focusing on a desired subject) by the small (spot) light control area. It is conceivable to perform light control. By executing this, the dimming area always exists on the subject, the amount of reflected light is constant, and the exposure is also appropriate. However, even if such a means is used, the subject is present outside the light control area from the beginning, or has already moved out of the light control area at the time of release even if it is within the light control area at the beginning. For this reason, there is a large possibility that the amount of flash light emitted is out of order and the exposure is not appropriate. The smaller the dimming area, the higher the probability of the occurrence of the inappropriate exposure.

Therefore, the present invention provides an automatic focusing camera that can increase the probability that the exposure will be appropriate by automatically performing spot dimming when the continuous mode is selected by the mode selection unit for automatic focusing control. The purpose is to:

[Means for Solving the Problems] In order to solve the above problems, an autofocus camera according to the present invention outputs focus detection information for driving a photographing lens to a focusing position, and drives the focusing lens to focus. An automatic focus camera capable of controlling a flash device, comprising: a detection drive unit; and a mode selection unit capable of setting a continuous mode, wherein the detection drive unit performs a continuous operation of repeating focus detection and focusing drive. First dimming means for performing flash dimming control by performing photometry on a first area of the object field including a part to be detected of the object detected by the focus detection driving means; and A second dimming unit that performs flash dimming control by metering a second area wider than the area; and when flash photography is started while the continuous mode is set by the mode selection unit, The first When the flash photography is started while the continuous mode is not set by the mode selection means, the second dimming means is caused to perform the flash dimming operation by the light means. And control means.

[Operation] According to the autofocus camera of the present invention, when flash photography is started while the continuous mode is set by the mode selection means, the photographer positions the subject on the screen at a desired position. Therefore, it is less likely that the exposure will be inappropriate even if the first dimming means performs the flash dimming operation. In addition, when flash photography is started while the continuous mode is not set by the mode selection means, it is expected that the photographer may not have captured the subject at a desired position on the screen, By causing the second dimming means to perform a flash dimming operation, the flash dimming operation can be performed on the safe side with respect to obtaining an appropriate exposure.

Embodiment FIG. 1 is a block diagram of an embodiment of the present invention. In this flash dimmer, various devices are controlled by a control circuit 1 including a CPU and the like. The lens ROM 2 outputs the release F value, the focal length, the exit pupil, and the like of the mounted photographing lens. DX code 3 outputs film sensitivity and the like. The photometric circuit 4 measures and outputs the luminance of the object scene. Exposure control circuit 5
Calculates an exposure value from data of the photometry circuit 4 and controls a shutter and an aperture based on the exposure value. The AF (automatic focus detection) mode selection circuit 6 selects either the continuous mode or the one-shot mode. Here, the continuous mode is a mode in which a focusing operation is repeatedly performed, for example, when photographing a moving subject, and the one-shot mode is a mode in which the focusing operation is performed only once on the subject. This is a mode in which the focusing operation is locked thereafter. The focus detection circuit 7 detects and outputs a focus. AFE is a signal line that transmits an H-level signal when a focus state is achieved and transmits the focus state to the control circuit 1. The lens drive circuit 8 drives the focus adjusting lens of the photographing lens to the in-focus position according to the output of the focus detection circuit 7. According to the embodiment, the detection driving means of the present invention comprises a focus detection circuit 7 and a lens driving circuit 8, and the mode selection means is an AF mode selection circuit 6.
And the first dimming means and the second dimming means are
Consists of The control means is the control circuit 1.

Sx is a synchro contact that is turned on when the shutter is fully opened and starts flash 10 emission. FS is the dimming circuit 9
And a signal line for transmitting an H-level signal and outputting a flash emission stop signal to the flash 10 when the integrated value of the light intensity reaches a predetermined value.

SW1 is a half-press switch that is turned on when the release button is half-pressed, and SW2 is a full-press switch that is turned on when the release button is fully pressed.

FIG. 2 is a cross-sectional view schematically showing the focus detection and dimming system of the camera. In FIG.
Is the taking lens barrel, 22 is the main mirror, 23 is the sub mirror, 24
Is a shutter, 25 is a film, 26 is a focus detection system, 27 is a condenser lens, and 28 is a multi-division light receiving element for dimming. FIG. 3 is a virtual diagram showing a multi-segment light receiving element 28 and a focus detection area 29 on a finder screen. This multi-segment light receiving element
3 is divided as shown in FIG. 3 so that, for example, when viewed through the viewfinder of the camera, the central area 28a overlaps with the focus detection area 29 (which is not actually visible). That is, the focus detection unit of the subject is always measured at the center of the multi-segment light receiving element 28.

The light beam (not shown) passing through the taking lens 21 is
At 22 the image is divided into a finder system and a focus detection system. The light beam to the focus detection system enters the focus detection system by the sub mirror 23 after passing through the main mirror 22, and is used for distance measurement for autofocus. The light beam to the finder system is
The light is observed through a pentaprism 32 and an eyepiece 33.

When the shutter is released, the main mirror 22 and the sub-mirror 23 are raised, and at the same time as the flash tube 30 emits light,
The reflected light from (25), that is, (natural light) + (flash reflected light) is received by the multi-segment light receiving element. When the integrated value of the amount of light received by the multi-segment light receiving element 28 reaches a predetermined value, the flash tube stops emitting light.

The operation of the flash dimmer of the automatic focusing camera configured as described above will be described with reference to the flowchart of FIG. FIG. 4 is a flowchart showing the operation of the flash dimmer of the automatic focusing camera according to the present invention. In the present embodiment, the automatic focus detection operation is performed according to the half-pressed state of the release button. Once the photographing lens is driven to the in-focus position, the focusing of the photographing lens is performed during the half-pressed state of the release button. The one-shot mode in which the operation is locked and the continuous mode in which the automatic focusing operation is repeated while following the moving subject, for example, while the release button is half-pressed, can be selectively taken.

In FIG. 4, the release button half-press switch SW
When this processing procedure is started when 1 is turned on, it is first determined in step S1 whether or not flash photography has been performed. Step S1
If the result is negative, then normal AE shooting is performed and has no bearing on the present invention, and a description thereof will not be repeated.

In the case of flash photography, it is determined in step S2 whether or not to perform automatic focus detection control. If the result of the determination in step S2 is negative, normal flash photography is performed, which is not relevant to the present invention. If affirmative in step S2, it is determined in step S3 whether the AF mode is the continuous mode.

If the result in step S3 is affirmative, the focus is detected in step S4, and the lens is driven in step S5. Then, in step S6, it is determined whether or not the switch SW2 is on.If not, it is determined in step S15 whether or not the switch SW1 is on.As long as the switch SW1 is on, steps S4 to S6 are repeated. , And enters a release standby state. If the switch SW1 is not turned on, it is determined that the finger has been released from the release button, and the process proceeds to return.

If the result in step S6 is affirmative, in step S7, only the central region 28a of the multi-segment light receiving element 28 is used as a light receiving element for light control, and spot light control photography is performed. That is, selecting the continuous mode and performing flash photography means that the photographer moves the camera while chasing the moving subject, for example, and determines that the subject is always located at a predetermined position (central region) on the photographing screen. Therefore, in this case, even if the spot dimming operation is performed, the possibility of improper exposure is reduced.

When the result in step S3 is negative, that is, when the AF mode is the one-shot mode, the focus is detected in step S8, and the lens is driven in step S9. In step S10, it is determined whether or not the camera is in focus. If the camera is not in focus, it is determined in step S13 whether the switch SW1 is on or not. As long as the switch SW1 is on, steps S8 to S10 are repeated.
If W1 is not on, it is determined that the finger has been released from the release button, and the process proceeds to return.

If focusing is affirmed in step S10, it is determined in step S11 whether or not the switch SW2 is on.If not, it is determined in step S14 whether or not the switch SW1 is on, and the switch SW1 is turned on. Step S
Steps S11 and S14 are repeated to enter the release standby state. If the switch SW1 is not on, it is determined that the finger has been released from the release button, and the process proceeds to return.

If the result in step S11 is affirmative, in step 12, divided light control photographing is performed using the entire area of the multi-divided light receiving element 28. That is, performing flash photography by selecting the one-shot mode indicates that the photographer may, for example, place the subject in an arbitrary position instead of the central area on the shooting screen and shoot. is there. For example, in one shooting, first place the subject in the center area of the screen, half-press the release button to complete the focusing operation, and then move the camera so that the subject comes to an arbitrary position on the screen with the in-focus position Shooting is performed by shaking and fully pressing the release button. Therefore, when the one-shot mode is selected, it is possible to perform divisional dimming shooting using the entire area of the multi-segment light receiving element 28 so that dimming control can be performed irrespective of where the subject is on the screen. Appropriate exposure is considered safe. Divided dimming is a known technique and will not be described in detail below.

[Effect of the Invention] As described above, according to the autofocus camera of the present invention, when flash photography is started while the continuous mode is set by the mode selection means, the photographer moves the subject on the screen. Since it is determined that it is captured at the desired position,
Even if a flash dimming operation is performed on the first dimming means, the possibility of improper exposure is reduced. In addition, when flash photography is started while the continuous mode is not set by the mode selection means, it is expected that the photographer may not have captured the subject at a desired position on the screen, By causing the second dimming means to perform the flash dimming operation, the flash dimming operation can be performed on the safe side with respect to obtaining an appropriate exposure.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a flash dimmer of an automatic focusing camera according to the present invention, FIG. 2 is a cross-sectional view of a camera schematically showing a focus detection and dimmer system, and FIG. FIG. 4 is a front view of the element, and FIG. 4 is a flowchart of one embodiment. [Description of Signs of Main Parts] 1 ... Control circuit 4 ... Photometry circuit 5 ... Exposure control circuit 6 ... AF mode selection circuit 7 ... Focus detection circuit 8 ... Lens drive circuit 9 ... Dimming circuit

Claims (4)

(57) [Claims] 1. A detection driving means for outputting focus detection information for driving a photographing lens to a focus position and driving the focus of the photographing lens, and a detection driving means for continuously operating focus detection and focusing drive repeatedly. And a mode selection unit capable of setting a continuous mode, wherein the flash unit can be controlled by an auto-focus camera, wherein the focus detection driving unit detects a subject to be detected by the first detection unit. A first dimming means for performing flash dimming control by photometrically measuring an area; and a second dimming control for performing flash dimming control by performing photometric measurement on a second area wider than the first area of the object scene. Means, when flash photography is started while the continuous mode is set by the mode selection means, causes the first dimming means to perform a flash dimming operation, and the mode selection means performs the flash dimming operation. An autofocus camera comprising: control means for causing the second light control means to perform a flash light control operation when flash photography is started while the continuous mode is not set. 2. The image processing apparatus according to claim 1, wherein said mode selection means includes: a one-shot mode in which a focusing operation of said photographing lens is prohibited once said photographing lens is driven to a focus position by said detection driving means; 2. The automatic focusing camera according to claim 1, wherein the camera can be selectively set. 3. A first area of an object field to be measured by the first light control means is a central area of the object field divided into a plurality of areas, and an object to be measured by the second light control means. 2. The auto-focus camera according to claim 1, wherein the second area of the field is the entire area of the field. 4. The auto-focus camera according to claim 3, wherein said second dimming means performs flash dimming by dividing an object field into a plurality of parts, measuring respective light amounts, and weighting each area.