| 摘要 |
PURPOSE:To form an exposure controlling mechanism of inexpensive constitution without making the mechanism complicated or large by using an optical element which has adhered or mixed material that changes transmissivity by reacting to light from an object to be photographed for an optical system as a camera composing element. CONSTITUTION:A photochromic glass which has mixed photochromic material whose transmissivity changes reacting to the brightness of the light from the object to be photographed is used for a photographing lens 2, one or more photographing lenses for a finder 3 and an window glass of a light emitting window for AF or light receiving lens. The transmissivity of the photochromic glass is the same as a normal glass when weak light is applied, however, when strong light is applied, the density increases. The glass density increases almost in proportion to the incident light, and the glass has the characteristic of keeping the strength of the transmitted light almost stable, and the exposure control range of the camera is widened. Thus, the exposure control mechanism is facilitated. |
