| 摘要 |
A device (10) for changing the focus and field of view magnification of an optical device having a two lens optical element (19, 21) which is movable grossly to change field of view and movable incrementally to change focus of the device (10) with either field of view includes an operator actuatable control system fo varying incrementally the axial position of this optical element within each of the regions to focus the optical device in each field of view mode. The device (10) includes a control knob (31), a threaded shaft (33) coupled to the control knob (31), a pair of stop members (37, 39) engaging threadedly the threaded shaft, and a linkage (45, 53, 49, 63, 59, 55, 67, 69) for converting axial motion of a stop member along the threaded shaft to incremental movement of the movable optical element along the primary optical axis (29). The threaded shaft (33) has a right hand thread along a portion of the length thereof engaging threadedly one stop member (39) and a left hand thread along another portion of the length thereof engaging threadedly the other stop member (37) so that the direction or sense of control knob motion necessary to increase the focus distance is the same in each of the two magnification modes.
|
