| 摘要 |
PURPOSE:To provide an inexpensive phase difference detection type automatic focusing device where a field lens having negative power is arranged behind an image pickup equivalent surface, a pair of separator lenses and a phase difference detecting device are arranged in order behind the field lens and the number of parts of an optical member is reduced to decrease position adjusting elements. CONSTITUTION:A luminous flux divided to detect focus by a split prism 7 is focused by a pair of separator lenses 4 and 4 through a field lens 24 having the negative power to be formed into an image on a pair of line sensors 8 and 8 in a phase difference detecting device 5 positioned behind the lenses 4. Then, a phase difference is calculated by a processing circuit 25 in the device 5 based on deviation between a pair of object images formed on the line sensors 8 and 8, and focusing is executed by moving a focusing lens group 26 in an optical axis direction based on the calculated phase difference. |
