| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a lens system with which unconfortable feeling and unnaturalness resulting from the phenomenon that the brightness of a screen is rapidly reduced in the vicinity of a telephoto end due to the original ramping characteristics of a photographing lens and from a porthole at the time of zoom operation can be reduced by simulatively generating desired ramping characteristics by controlling an iris to perform diaphragming when the focal distance is larger than the prescribed value with the iris open. <P>SOLUTION: A microcomputer 20 sets the open value of the iris I in accordance with the focal distance detected by a zoom position detector ZP when compulsive ramping is set ON and, for example, when the focal distance is altered with the iris open and the iris I is to be open wider than the open value, diaphragming is performed on the iris I till the open value. Thus, desired ramping characteristics is generated. In the ramping characteristics by the compulsive ramping, the brightness of the screen in the vicinity of the telephoto end is reduced more gently than in the original ramping characteristics of the photographing lens. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
