1. Field of the Invention
The present invention relates to an image pickup device suitable for a digital single lens reflex camera.
2. Description of the Related Art
In a known single lens reflex camera, a light emission of a strobe is automatically controlled by a TTL system. In case of a single lens reflex camera using a silver-halide film, diffused light reflected from a photographic emulsion surface of the film is received and detected by TTL light receiving elements. In recent years, digital single lens reflex cameras in which an image pickup device such as CCD is used instead of a photographic film have been widely used. In a known image pickup device used in a digital camera, a micro lens is provided in front of a photoelectric transducer to effectively transmit object light incident through a photographing lens to the photoelectric transducer. To enhance the dynamic range, it has been proposed to provide a light reducing filter made of a material having a reflectance not more than 50% between a part of photoelectric transducers and a color filter (see Japanese Unexamined Patent Publication No. 2003-273338). Moreover, it has also been proposed to coat front and rear surfaces of a ferroelectric film in the form of a micro lens with transparent electrode layers so as to vary the reflectance (Japanese Unexamined Patent Publication No. 2001-332711).
However, since the reflectance at the incident side surface of the image pickup device provided in a digital single lens reflex camera is small, a flash of light emitted from a strobe of a TTL auto strobe system and reflected from an object to be photographed is hardly reflected by the incident surface of the image pickup device and, hence, a small amount of the object light is made incident upon the TTL light receiving elements. Consequently, the output of the TTL light receiving elements is extremely small. As a result, the peak value in the photometering sensitivity distribution of the TTL light receiving elements is deviated from the center, and the photometering sensitivity distribution exhibits a steep curve and the output largely varies in accordance with the movement of the position of an exit pupil of a photographing lens. Also, the Av-response (proportional relationship between the actual aperture opening degree and the output) is not good. In the arrangement disclosed in Japanese Unexamined Patent Publication No. 2003-273338 in which the light reducing film is provided on a part of the photoelectric transducers, the output of the TTL light receiving elements largely varies depending on the position or shape of the object on the image surface, for the same object distance. In the solution disclosed in Japanese Unexamined Patent Publication No. 2001-332711 in which the front and rear surfaces of the micro lens are coated with the transparent electrode layers, a part of light to be made incident upon a photoelectric transducer is incident upon another photoelectric transducer, resulting in a deteriorated image quality.