| 摘要 |
PURPOSE:To switch a photometric range at a low cost, by providing a diaphragm mechanism by which an effective luminous flux is made variable, in the vicinity of a double focus lens for condensing scattered light beams and making them incident to a photoelectric transducer. CONSTITUTION:A direct photometric optical system provided with a photographing lens 1, a quick return mirror 2 having a semitransparent mirror, a focal plate 3, a shutter film 7, a diaphragm 9, a double focus lens 10 and a photoelectric element 11 is shown in the figure. As for this double focus lens 10, a focal distance of a center inside part 10-1 is different from a focal distance of an outside part 10-2, image formation states by the inside and outside lenses 10-1, 10-2 are different from each other, and the photometric areas are varied in case when photometry is performed by reducing the diaphragm 9 and using only the inside lens 10-1, and in case when the diaphragm 9 is opened and the outside lens 10-2 is also utilized for photometry, respectively, by which the photometric function is switched. |
