| 摘要 |
In the production of half-tone photographic exposures in which supplemental flashing and/or bumping steps involving exposing a photosensitive sheet to non-image light, it is desirable to eliminate operator intervention. A half-tone screen (3) of a graphic camera is uniformly exposed by a pinhole light projector (11, 13) positioned off axis (140) with respect to the main optical projection axis (9). A light diffuser (12) is positioned intermediate a light source (11) and the pinhole (13) and has a variable density light attenuator pattern (Fig. 2) consisting of a plurality of circular lines for attenuating the light passing through the diffuser and aperture in a manner to produce uniform illumination of the half-tone screen. |
