| 摘要 |
PURPOSE:To measure the quantity of light of a light source properly in consideration of the staining of an image formation optical system by providing a measuring instrument for the quantity of ligh of the light source on the reverse side of a transparent part at part of a light source light arrival part outside the image reflecting area of an image reflecting mirror. CONSTITUTION:The image reflecting mirror 14 of a light metering device 19 has a mirror material 31 mounted on the surface of mirror glass 30. The mirror material 31 has an image reflection ineffective part 34, which is provided with the transparent part 35. A light quantity detector 36 which measures the quantity of light of the light source is fitted at the reverse side of this transparent part 35. The control over the light source 3 and the detection of the staining progress state of the image formation optical system are performed on the basis of the quantity of light measured at a light metering part near the light source and that measured by the device 19. |
