| 摘要 |
PURPOSE:To shorten a time for searching a reference area and to remove a trouble missing a shutter chance by comparing a video signal in a fixed comparing range of one photodetecting part out of a pair of photodetecting parts with a video signal in a comparing range of the other photodetecting part while changing the comparing range of the other video signal. CONSTITUTION:The photodetecting parts 6, 7 measure respective object images through a lens, the position of the lens is detected by a lens position detecting means 8 and the comparing range of a video signal outputted from the photodetecting part 6 is determined in accordance with the output signal of the means 8. An arithmetic means 10 compares the video signal in the comparing range with a video signal outputted from the photodetecting part 7 while changing the comparing range of the video signal obtained from the photodetecting part 7, finds out the interval between the object images of the photodetecting parts 6, 7 to calculate the focus value of the lens based on the interval. Consequently, the reference area can be rapidly searched and the troubles such as the miss of a shutter change can be removed. |
