| 摘要 |
PURPOSE:To take out focus-detecting-light from a pentagonal prism part with a simple constitution by providing the air layer formed at the junction faces of two light transmitting members to the reflecting part for taking out the focus-detecting- light. CONSTITUTION:Lower part 22 of a pentagonal prism 21 is cut off along a cut face 23 and further this lower part 22 is separated to the two portions 22-1, 22-2 along the cut face 25 assuming an angle of 45 deg. to the optical axis 24 of a finder system. After this, the prism is assembled to the original form so as to leave a bubble near the center of the cut face 25 and is bonded. In order to form such bubble, an adhesive agent is coated only on the portion 27 shown by diagonal lines. Such simple process enables the reflecting part directing the focus-detecting-light to a focus- detecting photo detector to be provided to the lower part of the pentagonal prism and enables the entire part of the device to be made lower in cost. |
