JP2849610B2 - Multi focus camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a multi-focus camera having a strobe with improved dimming limit distance.

(Prior Art) Normally, since a camera strobe has a limit in a maximum light emission amount, there is a limit in a dimmable distance determined by a film sensitivity and an open aperture value of a lens. For example, sensitivity ISO1
00 film, f / 4 aperture lens, guide number
With the GN12 strobe, the limit is 3m, and subjects farther than this will be underexposed. In addition, with conventional cameras, the strobe light is applied uniformly throughout the angle of view so that the entire area of the angle of view is uniformly irrespective of the subject, regardless of the position within the angle of view. , The light controllable distance was constant within the angle of view.

FIG. 6 is a diagram showing a dimming limit by a strobe;
The vertical axis represents the distance to the subject (m), and the horizontal axis represents the angle of view (degree) of the lens. In the conventional camera, as shown by the line a in the drawing, the strobe light is distributed so that the angle of view is uniformly irradiated.

FIG. 7 is a diagram showing a dimming limit of a zoom strobe of a camera having a zoom lens. That is, FIG. 7A shows the dimming limit line a1 on the wide-angle side, and FIG.
Indicates a dimming limit line a2 on the telephoto side. Normally, when the open aperture value (F-number) of the photographing lens does not change between the wide-angle side and the telephoto side, the dimming limit distance becomes long because the telephoto side is focused. However, in practice, the aperture value on the telephoto side must be increased in order to reduce the size and cost of the lens. For this reason, the dimming limit on the telephoto side where loss due to the lens system is large is generally short.

In any case, the lines a1, a in FIGS. 7 (a) and 7 (b)
As shown in FIG. 2, the light was distributed such that the object within the angle of view was uniformly irrespective of the subject, regardless of whether the object was on the wide-angle side or on the telephoto side.

(Problems to be Solved by the Invention) As described above, regardless of the position of the subject within the angle of view, the strobe of the single focus camera or the zoom strobe of the zoom camera always has a uniform angle of view. Since the strobe light was distributed so as to irradiate the image, the dimming limit distance was almost the same in any direction within the angle of view. For this reason, when the subject is located only at the center within the angle of view, the light going to the periphery is wasted, and the dimming limit distance is short.

An object of the present invention is to provide a multi-focus camera capable of increasing a dimming limit distance by distributing strobe light to a center in an angle of view when a subject is located only in the center of the angle of view. It is in.

[Configuration of the invention]

(Means for Solving the Problems) A multi-focus camera according to the present invention measures the distance to a subject by inputting reflected light from the subject, focuses a photographing lens, and moves the subject within an angle of view. A multi-focus device that can determine whether it is located only at the center, and a normal light distribution angle that illuminates the entire angle of view determined by the focal length of the photographic lens with the light distribution angle of the strobe, and illuminates the central portion of the above angle of view A strobe light distribution angle variable device that can be changed to any of the center light distribution angles, and the strobe light distribution angle variable device when the multi-focus device determines that the subject is located only at the center within the angle of view. And a strobe light distribution angle control means for controlling the light distribution angle of the strobe light to the central light distribution angle.

(Operation) In the present invention, when the multi-focus device determines that the subject is located only at the center within the angle of view, the strobe light is controlled to be distributed to the center within the angle of view. As a result, the light control limit distance can be increased, and the number of underexposed photos can be reduced.

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

First, the schematic structure of the multi-focus camera will be described with reference to FIG. In FIG. 1, reference numeral 11 denotes a camera body, on the front of which a photographic lens 12, a viewfinder 13, a multi-focus light projecting lens 14, a light receiving lens 15, and a light emitting unit of a strobe 16 are provided. In this embodiment, a zoom lens is used as the photographing lens 12, and a zoom strobe is also used as the strobe 16. The zoom strobe changes the light distribution angle of the strobe in accordance with a change in the focal length of the zoom lens. In other words, when the focal length is short on the wide angle side, the light distribution angle is as shown by the dimming limit line a1 in FIG. 7A, and when the focal length is long on the telephoto side, the light distribution angle shown in FIG. It is configured to have a light distribution angle like the light limit line a2.

Next, the control section of the camera will be described with reference to FIG. Numeral 18 denotes a multi-focus device for multi-focus beams (three-point distance measurement) from a plurality of (three in the example in FIG. 4) light-emitting elements IR1, IR2, and IR3 for subjects 19a and 19b as shown in FIG. 1, 18-2, 18-3 are projected through the light projecting lens 14, and reflected light incident from the subjects 19a, 19b via the light receiving lens 15 is received by the light receiving element PSD,
From the receiving position of each reflected light, the subject 19 is determined by triangulation.
It measures the distance to a and 19b. The light emitting element I
R1, IR2, and IR3 are sequentially controlled to be turned on by a lighting control circuit 22 that operates according to a distance measurement command from a microcomputer (hereinafter referred to as a microcomputer) 21. The outputs △ I ₁ , か ら I ₂ from the light receiving element PSD are input to a distance detection circuit 23, where the object distance for each of the beams 18-1, 18-2, 18-3 is obtained, and 4 bits Is input to the microcomputer 21 as a digital signal.

In the example of FIG. 4, the subject 19b is the background, and the distance to infinity is measured by the reflected light based on the corresponding beams 18-1 and 18-3. The subject 19a is an object to be photographed, and the center beam 18
A predetermined subject distance is measured by reflected light based on -2. That is, since the multi-focus device 18 measures the distance for each of the multi-focus beams 18-1, 18-2, and 18-3, the distance to the subject 19a to be photographed is measured, and the distance between the subject 19a and the subject 19a is measured. It is possible to determine whether or not the lens is located only at the central portion within the angle of view determined by the focal length of the taking lens 12.

Referring back to FIG. 1, reference numeral 25 denotes a lens drive circuit which drives a stepping motor 26 so as to focus the photographing lens 12 in accordance with the subject distance.

28 is a zoom drive circuit, based on instructions from the photographer,
The zoom motor 29 is driven to change the focal length of the photographing lens 12, which is a zoom lens, to an arbitrary value. The zoom position of the photographing lens 12 is input to the microcomputer 21 by the zoom position detector 30.

Reference numeral 31 denotes a strobe light distribution angle varying device, which drives a motor 33 by a zoom strobe drive circuit 32 so as to change the strobe light distribution angle to a predetermined value corresponding to the focal length of the photographing lens 12 as described above. The light distribution angle is detected by the zoom strobe position detector 34 and input to the microcomputer 21.

As shown in FIG. 3, the zoom-type strobe 16
Condenser Fresnel lens 36 that forms the surface of the light emitting section
Behind (right side in the figure), a strobe light emitting tube 37 is provided so as to be displaceable in the front-rear direction (left-right direction in the figure), and the light distribution angle is changed by the movement in the front-rear direction. That is, 37a1 indicates that the strobe light emitting tube 37 is located at the position where the strobe light 36a1 having the normal light distribution angle on the wide angle side is emitted. Also, 37a2 indicates that the strobe light emitting tube 37 is at a position on the telephoto side where the strobe light 36a2 emits light with a normal light distribution angle. FIG. 7 (a) shows the normal light distribution angle.
As shown by the dimming limit lines a1 and a2 in (b), it means a conventional light distribution angle that uniformly irradiates the entire imaging angle of view on the wide-angle side and the telephoto side.

The normal light distribution angle is set in accordance with the focal length of the photographing lens 12 so as to uniformly irradiate the entire angle of view at the focal length. Positions 37b1, 37 behind the light angle positions 37a1, 37a2
When shifted to b2, strobe light 36a1, 36a at normal light distribution angle
Strobe light 36b distributed so that it is focused at the center from 2
1,36b2 occurs. That is, the above-described strobe light distribution angle varying device 31 adjusts the light distribution angle of the strobe to the normal light distribution angle for irradiating the entire angle of view determined by the focal length of the photographing lens, and the central light distribution angle for irradiating the center of the angle of view. It is possible to change to the light angle.

As shown by the dimming limit lines b1 and b2 in FIGS. 7 (a) and 7 (b), the strobe lights 36b1 and 36b2 at the above-mentioned central light distribution angle are not focused on the entire field angle of the corresponding focal length but at the central portion. Since the light is emitted, the light control limit distance at the center of the angle of view is larger than the light control limit distance at the normal light distribution angle. Therefore, when the subject is located only at the central portion of the angle of view, switching to the central light distribution angle increases the dimming limit distance and accordingly reduces the number of underexposed photographs.

Here, the microcomputer 21 can recognize the subject distance and determine whether the subject is located only at the center based on the data from the multi-focus device 18. Therefore, the microcomputer 21 controls the strobe light distribution angle to the central light distribution angle by detecting that the subject is located only at the center of the angle of view. That is, when the multi-focus device 18 determines that the subject is located only in the center of the angle of view, the microcomputer 21 changes the light distribution angle of the strobe to the central light distribution angle by the strobe light distribution angle varying device 31. It functions as a strobe light distribution angle control means for controlling.

Next, the operation will be described with reference to the flowchart of FIG. First, by turning on a release switch (not shown) provided on the camera body 11 (step
101), the multi-focus device 18 operates (step 10)
2) Multi-focus beams 18-1, 18-2, and 18-3 are sequentially emitted from the three light emitting elements IR1, IR2, and IR3 via the light projecting lens 14, and reflected light from the subjects 19a and 19b, Light receiving element P
The subject distance is measured from the incident position with respect to SD.

Here, as described above, the multi-focus beam 18−
1, 18-2 and 18-3 measure the distances to the corresponding subjects independently and individually. In the example of FIG. 4, the subject 19a to be photographed is measured by the multi-focus beam 18-2 projected at the center of the angle of view.
The microcomputer 21 determines which of the multi-focus beams 18-1, 18-2, 18 from the emission timings of the three light emitting elements IR1, IR2, IR3.
-3, the distance to the subject 19a to be photographed has been measured, in other words, the position within the angle of view where the subject to be photographed is located is known. It is determined whether or not the subject 19a is located only at the center within the angle of view (step 103).

As a result of the above determination, the subject is not only in the center of the angle of view,
If it is located in another portion, the light distribution angle of the strobe 16 is set to the normal light distribution angle corresponding to the focal length of the photographing lens 12 (step 104). Therefore, the strobe light emitting tube 37 is positioned at a position 37a1 (in the case of the wide angle side) or 37a2 (in the case of the telephoto side) in FIG. Light is emitted (step 107).

On the other hand, when the subject 19a is located only at the center within the angle of view, first, it is determined whether the subject 19a is longer than the dimming limit distance at the normal light distribution angle (step 105). This determination is made by comparing the distance to the subject 19a with the preset light control limit distance.

As a result of the determination, if the distance is within the dimming limit distance, an appropriate exposure can be obtained with the strobe light at the normal light distribution angle, so that the normal light distribution angle is set as it is as described above (step 104). ) To emit light (step 107).

On the other hand, when the subject is located beyond the dimming limit distance in the normal light distribution angle, the central light distribution angle for distributing the strobe light to the center is larger than the normal light distribution angle determined by the focal length of the imaging lens 12. (Step 106). Therefore, the strobe light emitting tube 37 is positioned at the position 37b1 in FIG.
Strobe light 36b positioned at (wide-angle side) or 37b2 (telephoto side) and focused at the center within the corresponding angle of view
Emit 1,36b2 (step 107).

When the strobe 16 is set at the central light distribution angle to emit light in this manner, the light control limit distance increases as shown by the light control limit lines b1 and b2 in FIGS. Is less than the dimming limit distance at the normal light distribution angle, the possibility of underexposure is low. That is, when the light is set at the central light distribution angle and condensed at the center, the light amount at the center increases, and the guide number GN substantially increases. For example, in the case of a film with a sensitivity of ISO 100, a lens with an open aperture of F4, and a strobe with a guide number of G.N12, the normal light distribution angle is limited to 3 m, but when set to the central light distribution angle,
Since the strobe light is focused at the center, the guide number is
G.N16, the dimming limit is increased to 4m with F4 lens.
As described above, since the dimming limit distance can be substantially increased, the number of underexposed subjects can be reduced.

That is, in general, conventional cameras often use a small built-in strobe with a small guide number GN for miniaturization, so that the strobe light reach is short and underexposure is likely to occur. like,
If the subject is located only in the center of the angle of view, the light distribution angle is set so that the strobe light is focused in the center. The subject that can be enlarged and underexposed can be reduced.

Although the zoom camera has been described in the above embodiment, the present invention can be applied to a single focus camera or a multiple focus camera. In the case of a single focus camera, the strobe 16
What can select any one of the normal light distribution angle which produces the dimming limit line a and the central light distribution angle which produces the dimming limit line b shown in the figure may be used.

Further, as the multi-focus device 18, a three-point multi-focus is exemplified, but a multi-focus of three or more points may be used. Further, although the active focus has been described as the multi-focus device 18, it is needless to say that a passive focus may be used.

In addition, the built-in camera type is exemplified as the strobe 16,
Of course, an external strobe may be used. As a means for changing the light distribution angle of the strobe, an example in which the strobe light emitting tube 37 is displaced has been exemplified, but the present invention is not limited to this.
For example, the lens 36 may be shifted.

Also, a motor was used to change the light distribution angle of the strobe,
Other driving devices may be used.

〔The invention's effect〕

As described above, according to the present invention, when the subject is located only at the center within the angle of view, this state is detected and the strobe light is distributed to the center, so that the dimming limit distance is large. And underexposed photographs can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the multi-focus camera according to the present invention, FIG. 2 is a front view showing the appearance of an embodiment of the multi-focus camera according to the present invention, and FIG. 3 is shown in FIG. FIG. 4 is a layout view of the internal structure of the strobe of the multi-focus camera as viewed from above, FIG. 4 is a conceptual diagram illustrating the relationship with the subject at the time of shooting, FIG. 5 is a flowchart illustrating the operation of the present invention, and FIG. Fig. 7
The figure is a characteristic diagram for comparing a dimming limit line based on a normal light distribution angle of a strobe with a dimming limit battle based on a central light distribution angle. 12 a photographing lens, 16 a strobe, 18 a multi-focus device, 19a, 19b a subject, 21 a microcomputer having a strobe light distribution angle control means as a function,
31… Strobe light distribution angle variable device.

Claims (1)

(57) [Claims] 1. A multi-function device capable of measuring a subject distance by inputting reflected light from a subject, performing a focusing operation of a photographing lens, and determining whether the subject is located only at the center of an angle of view. A focusing device and a strobe whose light distribution angle can be changed to one of a normal light distribution angle for irradiating the entire angle of view determined by the focal length of the photographing lens and a central light distribution angle for irradiating the center of the above-mentioned angle of view. A light distribution angle varying device, when the multi-focus device determines that the subject is located only at the center of the angle of view, the strobe light distribution angle varying device changes the light distribution angle of the strobe to the central light distribution angle. And a strobe light distribution angle control means for controlling the strobe light distribution angle.