Photography – With object illumination for exposure – Having preexposure illumination
Reexamination Certificate
2001-09-19
2003-01-28
Perkey, W. B. (Department: 2851)
Photography
With object illumination for exposure
Having preexposure illumination
C396S182000
Reexamination Certificate
active
06512890
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multi-flash photography system, wherein the amount of light of the main flash discharge is controlled in accordance with photometric readings obtained at a pre-flash emission.
2. Description of the Related Art
Various types of multi-flash photography systems in which the amount of light of the main flash discharge is controlled in accordance with photometric readings obtained at a pre-flash emission (a preliminary flash emission) that is emitted before the main flash discharge are known in the art. In conventional multi-flash photography systems, when a plurality of flash devices are activated to emit the pre-flash emission, the calculation for determining the amount of light of the main flash discharge for each flash device is very complicated because various settings (e.g., an illumination angle setting, a subject distance setting, a guide number setting, etc.) on each flash device are generally different from those on another flash device. In order to simplify such a calculation, a multi-flash photography system in which a plurality of flash devices are divided into several groups so that the pre-flash emission is emitted by each group of flash devices is also known in the art. However, in the case of using a plurality of slave flash devices, the flash emission operation of which is controlled via a light signal (wireless command signal) emitted by either an external flash device connected to the camera or a built-in flash of the camera, the number of such wireless command signals issued by either the external flash or the built-in flash (i.e., the number of the light-signal emissions emitted by the external flash or the built-in flash) increases if the pre-flash emission is emitted by each group of flash devices. This reduces the electrical power efficiency of a battery therefor.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a multi-flash photography system in which the pre-flash emitting operation can be controlled with a high degree of energy efficiency.
To achieve the object mentioned above, according to an aspect of the present invention, a flash photography system is provided, having a camera body and a plurality of external flash devices electrically connected to the camera body, the plurality of external flash devices being activated to emit a preliminary flash emission before a main flash emission. The camera body includes a designating device for designating a sync flash mode for the main flash emission from among at least one sync flash mode; a first pre-flash emission mode in which the plurality of external flash devices are activated to emit the preliminary flash emission at the same time; a second pre-flash emission mode in which the plurality of external flash devices are activated to emit the preliminary flash emission in a predetermined order; and a pre-flash emission mode selecting device which selects one of the first pre-flash emission mode and the second pre-flash emission mode in accordance with the designated sync flash mode.
Preferably, the at least one sync flash mode includes a successive sync flash mode in which the plurality of external flash devices are activated to discharge in a predetermined emission sequence, and the pre-flash emission mode selecting device selects the second pre-flash emission mode in the successive sync flash mode. The pre-flash emission mode selecting device selects the first pre-flash emission mode when not in said successive sync flash mode.
Each of the plurality of external flash devices can include a sync mode request setting device for manually selecting a sync flash mode as a sync mode request, wherein the sync mode request is transmitted to the designating device of the camera body to request the each external flash device to discharge in the selected sync flash mode. The designating device designates a sync flash mode for the main flash emission in accordance with the sync mode requests set by the sync mode request setting device of each of the plurality of external flash devices.
If the second pre-flash emission mode is selected, the plurality of external flash devices are activated to emit the preliminary flash emission in the predetermined order in the sync flash mode selected according to the sync mode request.
Preferably, the designating device designates a sync flash mode for the main flash emission in accordance with the sync mode requests set by the sync mode request setting device of each of the plurality of external flash devices.
According to another aspect of the present invention, a flash photography system having a camera body, at least one external flash device which is electrically connected to the camera body, and at least one slave flash device, wherein the at least one external flash device and the at least one slave flash device are activated to emit a preliminary flash emission before a main flash emission. The flash photography system includes a designating device for designating a sync flash mode for the main flash emission; a first pre-flash emission mode in which the at least one external flash device and the at least one slave flash device are activated to emit the preliminary flash emission at the same time; a second pre-flash emission mode in which the at least one external flash device and the at least one slave flash device are activated to emit the preliminary flash emission in a predetermined order; a pre-flash emission command device including a first command device which transmits a first command signal to the at least one external flash device; and a second command device which activates the at least one external flash device to emit a low flash emission serving as a second command signal to transmit the second command signal to the at least one slave flash device; and a pre-flash emission mode selecting device which selects one of the first pre-flash emission mode and the second pre-flash emission mode. The pre-flash emission mode selecting device selects one of the first pre-flash emission mode and the second pre-flash emission mode in accordance with the sync flash mode designated by the designating device in the case where only the first command device transmits the first command signal to the at least one external flash device. The pre-flash emission mode selecting device selects the second pre-flash emission mode regardless of the sync flash mode designated by the designating device in the case where the second command device activates the at least one external flash device to emit the low flash emission.
In an embodiment, if the first pre-flash emission mode is selected, the pre-flash emission command device controls an output timing of the first command signal and the second command signal so that the at least one external flash device and the at least one slave flash device are activated to emit the preliminary flash emission at the same time.
Preferably, the second command signal is specified by at least one time interval of at least two low flash emissions emitted by one of the at least one external flash device. The second command device activates the at least one external flash device to emit the low flash emission at an emission interval according to one of the first and second the pre-flash emission modes selected by the pre-flash emission mode selecting device.
Preferably, the pre-flash emission command device further includes a timer which expires after a predetermined period of time; wherein, in the first pre-flash emission mode, the timer is started, while the at least one external flash device is activated via the second command device to emit the low flash emission serving as the second command signal; the first command signal is transmitted to the at least one external flash device via the first command device upon expiration of the timer; and the at least one external flash device is activated again via the second command device to emit the low flash emission, serving as the second command signal, at the same time the transmission of the fir
Iwamoto Shigeru
Kawasaki Masahiro
Ohkura Tadahisa
Sato Osamu
Taneoka Kazuhito
Pentax Corporation
Perkey W. B.
LandOfFree
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