| 摘要 |
PURPOSE:To reduce the size, weight, and cost of an automatic focusing device by treating the reflecting surface of a spectral diffusing means into a total reflecting surfase provided at specific distance across the optical axis of a main photographic lens, and providing a reflection preventing means on its reverse surface. CONSTITUTION:Part of a light beam incident on a glass block 9 forms an angle of 90 deg. laterally and 45 deg. longitudinally to the optical axis of a lens group 1, and the light beam is reflected by a couple of total reflecting surfaces 10 at the specific distance from the optical axis, reflected by the final surface 6a of an aberration compensating lens, and further passed between the couple of total reflecting surfaces 10 to reach an automatic focusing sensor 7. On the other hand, part of the light beam reaching an image pickup element 5 through a relay lens 4 as to the light beam incident on the glass block 9 is reflected by the surface of the image pickup element 5 and returned to the glass block 9, but there is the reflection preventive surface 11 on the reverse surface of the total reflecting surface 10, so it is reflected and never reaches the automatic focusing sensor 7. Thus, the device is reduced in size, weight, and cost. |
