| 摘要 |
PURPOSE:To improve the operability in case a filter is attached and detached, by providing a photodetector for detecting a light which is varied in accordance with the installation of the filter, on a focus detecting device, and also correcting a discriminating output based on the output of this photodetector. CONSTITUTION:In case a filter F is not installed in front of a photographic lens 1, a projected light from a limit emitting element 6 is not made incident on a photoelectric converting element 12, therefore, the output of a comparins circuit 16 goes to a low level. Accordingly, a motor 25 executes focusing operation of the photographic lens 1 at a comparative high speed in accordance with a servo- output from a focus discriminating circuit 25. On the other hand, in case the filter F is installed, part of the projected light from the light emitting element 6 is reflected by the filter F and made incident on the photoelectric converting element 12, therefore, the output of the comparing circuit 16 goes to a high level. Accordingly, a sensor 7 repeats the detection of image of the reflected light based on a long accumulation time set to a circuit 17, and also the motor 25 executes the focusing operation of the photographic lens 1 at a comparatively low speed in accordance with a servo-output from a focus discriminating circuit 21 attenuated by an attenuating circuit 22. |
