Focus adjusting mechanism for variable magnification device

摘要

In an optical system including a plurality of projecting lenses mounted on a support plate and selectively usable by moving the support plate for projecting copy images at varying magnifications, a focus adjusting mechanism includes focus adjusting first means shiftable between an operating position and a nonoperating position, second means biasing the focus adjusting means toward the operating position for rendering a projecting lens adjustable by the focus adjusting means when the lens is positioned in the projecting position, and third means for shifting the focus adjusting means to the nonoperating position against the action of the second means to permit changing the lenses.