| 摘要 |
PURPOSE:To measure always accurate film density by mesuring the background density of a film outside the effective image plane range of the microfilm held in the opening of an aperture card. CONSTITUTION:Although the frame size of a 35mm. film is 31.8X45mm., an object is photographed within the range of a frame size 30.4X41mm.. Hence, the object stage of a flag bed camera is taken in the shaded part A. Since the object stage is white, this part is finished to roughly the same film density as that of the white ground part of the object. Hence, with the film taken for aperture card purpose, the change in photographing conditions and developing conditions is obtained easily through one time of density measurement by measuring the film density of the part A. Nevertheless, showing of wrong values owing to the information density of the object is ovbiated and always accurate film density is measured because the film density is measured outside the photographing range for the object. |
