Scale and focus mechanism for reproduction camera - has enlarging ratio scales on a cylinder and a focus coupled scale pointer

摘要

The top of the apparatus incorporates a rotatably cylinder which is coupled to the movement which varies the distance between the original and the film stage. The cylinder is marked with mathematical curves derived from calculated tables to show the enlargement or reduction ratios of various objectives at different original to film distances. A pointer moving axially along the cylinder is coupled to the focus mechanism which varies the objective to film distance. The cylinder curves and the pointer are coupled either mechanically, optically, magnetically, electrically or electronically. The design speeds and simplifies accurate setting up.