1. Field of the Invention
The present invention relates to a flashlight control device for controlling a light emission device such as a strobe.
2. Description of Related Art
Photographic cameras of so-called TTL (through-the-lens) photometric type (referred to hereinafter as "TTL light control cameras") are well known. In strobe photographing with this type of camera, a strobe light is reflected from a subject to be photographed to enter the photographing lens and is measured by a photometric sensor to achieve a light control of the strobe (i.e., control of flash termination). When the quantity of reflected light reaches an optimum level (TTL-Digital-Analog (DA) level) the flash is cut off, depending on a particular film speed, so as to obtain an optimum exposure.
However, in TTL light control cameras of the prior art, it has sometimes been impossible to achieve an optimum exposure for a scene composed of objects having significantly different reflectivities. For example, if the scene to be photographed contains an object having a reflectivity significantly higher than those of other objects in the same scene, the light control is sometimes based on only that portion of the strobe light that is reflected on this object and thus duration of strobe flashing becomes shorter, i.e., the picture will be under-exposed as a whole. On the other hand, if the light control is based on an object having a significantly lower reflectivity, the duration of strobe flashing increases, i.e., the picture will be over-exposed as a whole.
Some TTL light control cameras are provided with a so-called multi-photometric sensor, in which several areas of a scene to be photographed are measured by respective photometric sensors during so-called pre-flashing of the strobe. The sensor to be used is selected, depending on the measured reflectivity, before proper strobe flashing. The selected sensor is used for the light control (TTL-Auto Strobe Level control).
With this type of TTL light control camera, consideration can be given to the reflectivity of the scene to be photographed, however various factors, such as, the presence and influence of a filter attached to the photographing lens, can not be detected. In consequence, an optimum quantity of flash can not be obtained when the quantity of light transmitted through the photographing lens is reduced by the presence of the filter and the resulting picture is often under-exposed.
Some well known cameras having so-called multi-rangefinding (multi-AF) and multi-photometry functions, employ a flashlight control apparatus such that the photometric sensor, correspondingly associated with the AF sensor selected by multi-rangefinding is utilized for the light control. However, as in the case of the TTL light control camera mentioned above, it is sometimes impossible to obtain the optimum quantity of flash if the scene to be photographed is composed of objects having significantly different reflectivities.
USPTO Backgrounds
USPTO Backgrounds