Coupling mechanism for the alternate manual and automatic adjustment of a varifocal objective

摘要

A camming sleeve for the adjustment of the shiftable components of a varifocal objective is fixed to a surrounding coaxial control ring having a slot traversed by a knob which is rigid with a slider received in a recess between the control ring and the sleeve. The slider, which is indexable in two different axial positions, has a toothed edge engageable in one of these positions with a toothed face of a coupling ring, permanently connected via a step-down transmission with a reversible drive motor, which in the other slider position is freely rotatable on the camming sleeve so that the latter can be manually displaced by means of a handle rigid therewith.