Basic lens assembly for series of zoom objectives of different varifocal ratios
AssigneesKarl Vockenhuber, Raimund Hauser
InventorsWalter Besenmatter, Trude Muszumanski, Irmgard Wendisch
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Abstract
A zoom objective is disclosed which consists of a varifocal front lens group and a fixed rear lens group, the front lens group comprising a stationary first component of positive refractivity, axially shiftable second and third components of negative refractivity, and a stationary fourth component of positive refractivity separated from the rear lens group by a reflex prism adjoining a diaphragm space. The assembly of third and fourth components, prism and rear lens group can be selectively combined with various first and second components to provide zoom objectives of different varifocal ratios.
Claims8
A lens assembly forming part of a varifocal optical system of the type wherein a front lens group constituted by two stationary positive components bracketing two axially shiftable negative components adjoins an axially fixed rear lens group of positive refractivity consisting of a plurality of air-spaced lens members, said lens assembly comprising:
- an axially shiftable negative lens L.sub.6 constituting one of said negative components;
- an axially fixed positive lens L.sub.7 constituting one of said stationary components;
- and
- two positive lenses L.sub.8, L.sub.9, a negative lens L.sub.10 and another positive lens L.sub.11 constituting said air-spaced lens members;
- said lenses L.sub.6 - L.sub.11 having radii of curvature r.sub.6 ' - r.sub.11 ", axial thicknesses d.sub.6 - d.sub.11, refractive indices n.sub.d and Abbe numbers .nu..sub.d substantially as given in the following table along with air spaces s.sub.9 - s.sub.11 separating said lens members L.sub.8 - L.sub.11 :
- ______________________________________ n.sub.d .nu..sub.d ______________________________________ r.sub.6 ' = -0.87 L.sub.6 d.sub.6 = 0.05 1.78 44 r.sub.6 " = -2.20 r.sub.7 ' = +1.40 L.sub.7 d.sub.7 = 0.12 1.69 55 r.sub.7 " = -1.75 r.sub.8 ' = +2.19 L.sub.8 d.sub.8 = 0.11 1.74 45 r.sub.8 " = -3.17 s.sub.9 = 0.03 r.sub.9 " = +0.74 L.sub.9 d.sub.9 = 0.12 1.74 45 r.sub.9 " = .infin. s.sub.10 = 0.04 r.sub.10 ' = -0.99 L.sub.10 d.sub.10 = 0.35 1.85 24 r.sub.10 " = +0.57 s.sub.11 = 0.06 r.sub.11 ' = +1.69 L.sub.11 d.sub.11 = 0.23 1.74 42 r.sub.11 " = -0.59 ______________________________________
Dependencies are inferred from the claim text.