| 摘要 |
PURPOSE:To use titled devices even in case of a dark object to be photographed, and a dark optical system, by simple constitution, by projecting light to an object to be photographed, from a light source, through a photographic lens, and detecting an optical image reflected by the object to be photographed, by a photoelectic element having an opening part. CONSTITUTION:Light of a focusing light source 12 passes through an opening part of a pinhole 15, etc. of a photoelectric element 11, advances along an optical axis 7, and is projected toward a front object to be photographed 25 through a photographic lens 8. Light reflected by the object to be photogaphed 25 passes through the photogaphic lens 8 again, and reaches the photoelectric element 11 existing at a position conjugate to the surface of a film 22. When the object to be photgaohed 25 is at a position shown by a code (b), it is focused, and as for the reflected ray, the position of the pin hole 15 becomes a converging point, and a signal output becomes minimum. When the object to be photogaphed 25 is at a position shown by a code (a) or (c), the reflected ray reaches a photoelectric surface 17 of the outside circumference of the pinhole 15, a signal is outputted, and in accordance with its output, the photographic lens 8 moves. |
