| 摘要 |
PURPOSE:To provide a detection system for focal position with high accuracy by making the combined focal length of the entire detection system including a lens for detecting the focal position larger than the combined focal length as the entire system of a lens system for image pickup. CONSTITUTION:A luminous flux splitting element P is provided in a lens system for image pickup, and the luminous flux split by the element P is formed an image by a lens D for detecting focal position. The focal position is detected by measuring the image-forming position thereof. The combined focal length (f) as the entire system of the photographing lens system constituted of a focusing lens F, a zoom part Z and a master lens M and the combined focal length fD of the entire detection system consisting of a lens D for detecting focal position, the lens F and the zoom part Z are so set as to have the relation f<fD. |
