| 摘要 |
PURPOSE:To prevent the decrease in a quantity of light by using a semitransparent mirror in forming a part conducting light to the 2nd optical path of a light splitter and a total reflection mirror in constituting the other part. CONSTITUTION:The part between a lens group 4 and lens groups 7 and 9 is an afocal part, where a light splitter 5 of a glass block having a semitransparent mirror 6 is provided to split an incident luminous flux to the 1st optical path bending at a right angle and heading toward an imaging plane and the 2nd optical path advancing rectilinear and heading toward a finder. The sectional area on the light splitting surface of the luminous flux necessary for the finder is small as compared to the area of the incident luminous flux. Therefore the semitransparent mirror is used only in the part for feeding the necessary luminous flux to the finder and the total reflection mirror is used in all the other part to feed only the light necessary for the finder to the 2nd optical path and to feed all the remaining light to the image pickup part, whereby a quantity of light in the image is increased. |
