Photography – Flash system responsive to focal length or distance – Illumination angle responds to focal length or distance
Reexamination Certificate
2000-06-22
2002-02-12
Gray, David M. (Department: 2851)
Photography
Flash system responsive to focal length or distance
Illumination angle responds to focal length or distance
C396S178000, C396S202000
Reexamination Certificate
active
06347189
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flash controller of a camera system which includes a camera body and an interchangeable lens which is detachably attached to the camera body.
2. Description of the Related Art
In cameras having a built-in flash, specifically, in SLR cameras having a built-in flash to which an interchangeable lens is detachably attached, there is a possibility that the flashlight emitted from the built-in flash will be interrupted by the periphery of the attached interchangeable lens, so that the flashlight does not cover the center lower part of the object area, resulting in casting a shadow of the attached lens thereon. Specifically, if the attached lens is an extremely-wide-angle lens, the flashlight will not cover the periphery of the object area because the angle of view of the lens is generally greater than the flash coverage (cover angle of view) of the built-in flash, so that the flashlight will not reach the periphery of the object area, thus resulting in a lack of the quantity of light thereof. On the other hand, if the object distance is too short, the quantity of the flashlight is not properly controlled, which may result in an over exposure. Conversely, if the object distance is too long, a sufficient quantity of the flashlight will not be given to the object area, which may result in an under exposure. In these cases, if the flash emits automatically at a time of exposure, an undesired exposure will be obtained.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a flash controller of a camera system including a camera body and an interchangeable lens which is detachably attached to the camera body, which makes it possible to reduce the number of undesired exposures in the photography using flash.
To achieve the object mentioned above, according to an aspect of the present invention, a flash controller of a camera system is provided, including a camera body and an interchangeable lens which is detachably attached to the camera body, the camera body including a built-in flash, the interchangeable lens being of a type which can have data communication with the camera body to output lens data on the interchangeable lens to the camera body. The flash controller includes a memory which is provided in the camera body in which data on the built-in flash are pre-stored; and a calculating device, provided in the camera body, for judging whether flashlight emitted from the built-in flash will be interrupted by a periphery of the interchangeable lens in accordance with the lens data input from the interchangeable lens and flash data input from the built-in flash. According to this structure, it can be judged whether the flashlight emitted from the built-in flash will be interrupted by the periphery of the attached interchangeable lens in accordance with the input lens information. Therefore, if it is judged that the flashlight emitted from the built-in flash will be interrupted by the periphery of the attached interchangeable lens, the flashlight can be prevented from casting a shadow of the attached interchangeable lens on the center lower part of the object area by prohibiting the built-in flash from discharging at a time of exposure.
In an embodiment, the calculating device calculates a flash interruption value which represents quantity of light emitted from the built-in flash which is interrupted by the periphery of the interchangeable lens, and subsequently judges whether the flashlight will be interrupted by the periphery of the interchangeable lens in accordance with the calculated flash interruption value.
Preferably, an auto-flash prohibiting device is further provided, which prohibits the flash from automatically discharging if the calculating device judges that the flashlight will be interrupted by the periphery of the interchangeable lens.
In an embodiment, the camera body includes a multi-segment photometering device for determining whether an object to be photographed is in a backlit situation, the camera body providing an auto flash discharge mode, wherein the flash can discharge automatically at a time of exposure in the backlit condition. The calculating device judges whether the flashlight will be interrupted by the periphery of the interchangeable lens on condition that an object distance is longer than a predetermined distance and that a selected shutter speed is slower than the slowest shutter speed calculated to prevent blurred images which may be caused by hand movement of the camera body.
Preferably, the object distance is obtained via the data communication.
In an embodiment, the flash controller prohibits the flash from discharging in the case where the calculating device judges that an object distance is shorter than the predetermined distance and that the selected shutter speed is faster than the slowest shutter speed.
According to another aspect of the present invention, a flash controller of a camera body is provided, to which an interchangeable lens is detachably attached, the camera body including a built-in flash, the interchangeable lens being of a type which can have data communication with the camera body to output lens data on the interchangeable lens to the camera body. The flash controller includes a memory in which data on the built-in flash are pre-stored; and a calculating device for judging whether flashlight emitted from the built-in flash will be interrupted by a periphery of the interchangeable lens in accordance with the lens data input from the interchangeable lens and flash data input from the built-in flash.
In an embodiment, the calculating device calculates a flash interruption value which represents quantity of light emitted from the built-in flash which is interrupted by the periphery of the interchangeable lens, and subsequently judges whether the flashlight will be interrupted by the periphery of the interchangeable lens in accordance with the calculated flash interruption value.
Preferably, an auto-flash prohibiting device is further provided, which prohibits the flash from automatically discharging if the calculating device judges that the flashlight will be interrupted by the periphery of the interchangeable lens.
According to another aspect of the present invention, a flash controller of a camera system is provided, including a camera body, an interchangeable lens which is detachably attached to the camera body, and an external flash which is detachably attached to the camera body, the interchangeable lens being of a type which can have data communication with the camera body to output lens data on the interchangeable lens to the camera body, the external flash being of a type which can have data communication with the camera body to output flash data on the external flash to the camera body. The flash controller includes a calculating device, provided in the camera body, for judging whether flashlight emitted from the external flash will be interrupted by a periphery of the interchangeable lens in accordance with the lens data input from the interchangeable lens and flash data input from the external flash. According to this structure, it can also be judged whether the flashlight emitted from an external flash connected to the camera body will be interrupted by the periphery of the attached interchangeable lens in accordance with the input lens information if the flash information on the external flash can be input to the calculation device.
In an embodiment, the calculating device calculates a flash interruption value which represents quantity of light emitted from the external flash which is interrupted by the periphery of the interchangeable lens, and subsequently judges whether the flashlight will be interrupted by the periphery of the interchangeable lens in accordance with the calculated flash interruption value.
Preferably, an auto-flash prohibiting device which prohibits the flash from automatically discharging if the calculating device judges that the flashlight will be interrupted by the periphery of the interch
Hamamura Toshihiro
Hosokawa Tetsuo
Iwamoto Shigeru
Asahi Kogaku Kogyo Kabushiki Kaisha
Blackman Rochelle
Greenblum & Bernstein P.L.C.
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