| 摘要 |
A microfilm copying camera of the step-by-step type which permits adjustment of the ratio of the size of the picture to be taken (the copy) to the size of the picture to be copied (the master or original). The camera is provided with a light source of controllable intensity for illuminating the entire master; the light source is controlled by a photometer mounted on the camera and scanning a small test area of the master. The camera has an adjustable lens board, whereby the size of the copy may be varied. The photometer has a light sensitive element mounted in the plane of the camera film, and a lens which scans the test area which is mounted on the camera lens board and has a focal length equal to the focal length of the camera lens. The camera may have a shutter mechanism with a fixed opening and a constant exposure time, the only variable in the taking of the picture then being the variable illumination provided by the controlled light source. |
