| 摘要 |
PROBLEM TO BE SOLVED: To find out a true focal position of a fixed focus lens device with high precision by finding out two positions of a focus lens coincident with output values of an integration circuit equivalent to a limit resolution or a resolution lower than that of an image pickup element and fixing the focus at a position between the two positions. SOLUTION: A lens system of the fixed focus lens device 1 is made up of a stationary part 2 and a moving part 3 for focusing. Then a personal computer 11 drives a stepping motor 14 to move the moving part 3 of the lens to find out a position at which an output result of the integration circuit is a prescribed value. Then a position in excess of a maximum value giving the same detection result as that at the position found out at first is found out. A middle position between the two fond-out positions is calculated, the moving part 3 of the lens is moved to the position again. While keeping the state, a fixing screw 5 of the lens is tightened and fixed. Thus, the focusing is accurately and automatically matched by an instruction from a control section such as a personal computer. |
