| 摘要 |
PURPOSE:To improve the focusing performance by forming a diaphragm plate and a plate-like insertion member to such a shape as an aperture part by both of them always becomes single even if the aperture ratio is varied. CONSTITUTION:A shape of a small diaphragm side of each of diaphragm plates 1, 2 is constituted of two linear parts so that a shape of an aperture part 4 at the time of a small diaphragm becomes a square, and also, a shape of the aperture part side of an ND filter 3 which has been stuck to the diaphragm plate 2 is formed linearly. Accordingly, even if the aperture ratio is varied, the aperture part by the diaphragm plates 1, 2 and the ND filter 3 always becomes single, and it does not occur that plural aperture parts by the diaphragm plates 1, 2 and the ND filter 3 exist at the time of a small diaphragm. In such a way, the focusing performance of a video camera, etc., which have used automatic focus detecting device for executing its focusing, based on an output voltage of an image pickup element can be raised. |
