| 摘要 |
PURPOSE:To simplify the mechanism of a zoom lens by composing an image- forming lens group of a fixed and a movable lens group by adjusting the reference focal point of the zoom lens by the movement of the movable lens group, and performing focusing to an extremely near object by the movement of said reference point. CONSTITUTION:The zoom lens system consists of variable power optical systems I , II, and III, a fixed lens groups IV, and a movable lens group V; the movable lens group V is moved as shown in a figure (a) to adjust the reference position as shown by an arrow and the movable lens group V is moved as shown in a figure (b) to form the image of the extremely near object O on an image formation surface F. The optical system I has positive refracting power and performs normal focusing. The optical system II is a variator having negative refracting power and the optical system III is a compensator with negative refracting power. The lens IV is an afocal system, so the movement extent of the lens system V is equalized to that for the reference focal point adjustment. |
