| 摘要 |
PURPOSE:To obtain an approximately constant curve by constituting a contrast information unit of one or plural photoelectric bits constituting an image sensor, and changing the number of constituting photoelectric bits of this contrast information unit in accordance with the aperture F value of a lens. CONSTITUTION:The video output of each photoelectric bit B of an image sensor 2 is converted to a digital quantity and is stored in each address of a memory device 4. An arithmetic device 5 determines a combination of photoelectric bits B, namely, the number of photoelectric bits B constituting a contrast information unit C in accordance with the input of an aperture F value signal 6 of the lens and calculates contrast data of the contrast information unit C on a basis of outputs of one or plural photoelectric bits B and sends this contrast data to a contrast detector 7. The contrast detector 7 defines output differences of optional contrast data at certain intervals as contrast and finds its maximum value and inputs it to a focus detector 8, and the in-focus state, the front-focus state, the rear-focus state, discrimination impossibility, etc. are discriminated in accordance with inputted contrast information and are outputted to a display device 9. |
