| 摘要 |
PURPOSE:To make a lens unit compact by splitting light by a half-mirror and reflecting the light by a concave mirror, and passing the light through the half- mirror again and guiding it to a photosensor for focus adjustment. CONSTITUTION:The light split upward by the half-mirror block 7 arranged in front of the stop 5 of a photographic optical system is reflected totally and converged by a concave mirror 11 to travel downward, and the light is passed through the half-mirror 7 again to reach the photosensor 9 for focus adjustment. Therefore, the space from the half-mirror to the photosensor for focus adjustment which is required by the lens barrel of the optical system is used in common to the space that the half-mirror 7 occupies, and the lens unit for a camera including the automatic focus adjusting device is reduced in size and also made compact. |
