Photography – With exposure objective focusing means – focusing aid – or... – Optical detail with photoelement system
Reexamination Certificate
1997-07-03
2001-11-06
Mahoney, Christopher E. (Department: 2851)
Photography
With exposure objective focusing means, focusing aid, or...
Optical detail with photoelement system
C396S155000, C396S234000, C396S268000
Reexamination Certificate
active
06314241
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a camera having a shadow-occurring-state detecting means for detecting a shadow appearing at an object in taking a shot with the camera.
2. Description of the Related Art
The recent advancement of electronic control technology has enabled cameras of these days to permit taking shots in more versatile light adjusting states than old-fashioned cameras. Hence, cameras of varied kinds have been proposed in this respect and put on the market. These cameras, for example, include
(a) A camera arranged to measure the luminance of an object of shooting and to automatically cause a flash device to flash when the measured luminance is less than a predetermined value, for example, as disclosed in the specification of U.S. Pat. No. Re 29,599.
(b) A camera arranged to measure the luminance of a shooting object, to cause a flash device to fully flash when the measured object luminance is less than a predetermined value and to cause the flash device to perform daylight synchro-flash (fill-in flash) when the measured luminance is greater than the predetermined value, for example, as disclosed in the specification of U.S. Pat. No. 4,812,872; and
(c) A camera arranged to measure luminance obtained in a middle part and a peripheral part of a photo-taking picture plane and to automatically cause a flash device to flash when the shooting object is judged to be in a back-light state from a difference in luminance between the middle part and the peripheral part, for example, as disclosed in the specification of U.S. Pat. No. 4,666,280.
However, none of these cameras are arranged to detect and predict, on the basis of the direction and intensity of incident light coming from a light source, the state of a shadow appearing at the object at the time of taking a shot and to control photographing conditions according to the result of prediction.
SUMMARY OF THE INVENTION
It is one aspect of the invention under the present application to provide a camera which performs a photographing operation in a photographing condition suited for the state of a light source by detecting a shadow appearing in taking a shot according to the state of the light source. To attain this aspect, a camera according to the invention includes a light receiving element part for receiving a light flux coming from a light source, a processing circuit for deciding the direction and intensity of the light flux coming from the light source on the basis of an output of the light receiving element part, and a photographing condition setting circuit for setting a photographing condition according to a result of the decision made by the processing circuit.
To attain the above-stated object, a camera according to the invention is arranged to decide the direction and intensity of a light flux coming from a light source on the basis of a center-of-gravity position of an image formed on the above-stated light receiving element part and data corresponding to a ratio or a difference between a luminance value obtained at the center-of-gravity position and a luminance value obtained at a position located away from the center-of-gravity position. Another camera which attains the above-stated object is arranged to decide the direction and intensity of a light flux coming from a light source on the basis of a state of luminance distribution on the light receiving element part.
It is another aspect of the invention to provide a camera arranged to carry out a photographing operation in a mode suited for a photographing condition, for example, by causing a flash device to flash according to the instruction of an instructing circuit in anticipation of appearance of a shadow in a case where the object of shooting is being illuminated with an intensive light flux. To attain the aspect, a camera is provided with a light measuring circuit, a first comparison circuit for comparing a signal value corresponding to an output of the light measuring circuit with a predetermined value and for generating an output when the signal value is higher than the predetermined value, and an instructing circuit for giving an instruction for flash photography in response to the output of the first comparison circuit.
Under the object mentioned above, the camera is provided with a second comparison circuit for substantially comparing a value corresponding to the output of the light measuring circuit and a film sensitivity with a predetermined value and for generating an output when the predetermined value is higher, and an instructing circuit for giving an instruction for flashing in response to the output of the second comparison circuit. The camera is arranged to flash by controlling a flashing action in such a manner that a threshold level of the flashing is set in relation to the film sensitivity when an object luminance is low and the threshold level of the flashing is set at a predetermined luminance level irrespective of the film sensitivity when the object luminance is high.
Under the above-stated object, another camera is provided with a distance value signal forming circuit for forming a distance value signal corresponding to an object distance and an inhibiting circuit for inhibiting the instructing circuit from giving an instruction for flash photography when the distance value signal from the distance value signal forming circuit indicates a distance farther than a predetermined value. Thus, the camera is arranged such that flash photography is carried out only when the object is located in a distance range within which the above-stated shadow can be erased.
These and other objects and features of the invention will become apparent from the following detailed description of embodiments thereof taken in connection with the accompanying drawings.
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patent: 4908646 (1990-03-01), Sato et al.
patent: 5023649 (1991-06-01), Hayashi et al.
patent: 5111232 (1992-05-01), Tsunefuji
patent: 5266990 (1993-11-01), Sakamoto et al.
patent: 5311240 (1994-05-01), Wheeler
patent: 5440369 (1995-08-01), Tabata et al.
patent: 5483320 (1996-01-01), Aoki et al.
Canon Kabushiki Kaisha
Mahoney Christopher E.
Robin Blecker & Daley
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