Three-component varifocal objective
AssigneesKarl Vockenhuber, Raimund Hauser
InventorsTrude Muszumanski, Irmgard Wendisch
Life of this patent
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Abstract
A varifocal objective has an axially shiftable positive front component, an axially shiftable negative intermediate component, and a fixed positive rear component or basic lens group. The latter component consists of five closely spaced lens members, all but the second of them singlets and all but the third of them positively refracting. The intermediate component is separated from the rear component by a diaphragm space which in a position of close approach of these components, corresponding to maximum focal length, is still substantially greater than any air space between the lens members of the rear component. With a varifocal ratio close to 3:1, the distance between the front and rear components is the same in the positions of maximum and minimum focal lengths.
Claims16
A varifocal objective consisting of:
- an axially shiftable positively refracting front component;
- an axially shiftable negative refracting intermediate component;
- and
- an axially fixed positively refracting rear component constituted by five closely air-spaced lens members, namely a positive first lens member, a positive second lens member, a negative third lens member, a positive fourth lens member and a positive fifth lens member, the spacing of said intermediate component from said rear component in a position of maximum overall focal length substantially exceeding any air space between said lens members while being substantially smaller than in a position of minimum overall focal length, said front component consisting of a forwardly convex negative meniscus L.sub.1 followed by a biconvex lens L.sub.2 and a substantially planoconvex lens L.sub.3 with forwardly facing convexity, said second component consisting of a substantially planoconcave lens L.sub.4 rearwardly facing concavity followed by a biconcave lens L.sub.5 cemented onto a positive meniscus L.sub.6, said first lens member of said rear component being a biconvex lens L.sub.7, said second lens member consisting of a biconvex lens L.sub.8 cemented to a biconcave lens L.sub.9, said third lens member being a biconcave lens L.sub.10, said fourth lens member being a biconvex lens L.sub.11, and said fifth member being a substantially planoconvex lens L.sub.12 with forwardly facing convexity.
Dependencies are inferred from the claim text.