Basic lens assembly for series of zoom objectives of different varifocal ratios

Claim 2

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 6 constituting one of said negative components; an axially fixed positive lens L 7 constituting one of said stationary components; and two positive lenses L 8 , L 9 , a negative lens L 10 and another positive lens L 11 constituting said air-spaced lens members; said lenses L 6 - L 11 having radii of curvature r 6 ' - r 11 ", axial thicknesses d 6 - d 11 , refractive indices n d and Abbe numbers ν d substantially as given in the following table along with air spaces s 9 - s 11 separating said lens members L 8 - L 11 : ______________________________________ n.sub.d ν.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 " = ∞ 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 ______________________________________

Claim 3

A lens assembly as defined in claim 1, further comprising a prism with planar faces inserted between said positive lenses L 7 and L 8 , said prism being separated from lens L 7 by an air space s 8 ' and from lens L 8 by an air space s 8 ", the numerical values of said air spaces s 8 ' and s 8 " together with the thickness d p , refractive index n d and the Abbe number ν d of said prism being substantially as follows: ______________________________________ n.sub.d ν.sub.d ______________________________________ s.sub.8 ' = 0.05 d.sub.p = 0.25 1.52 64 s.sub.8 " = 0.09 ______________________________________

Claim 4

The combination of a lens assembly as defined in claim 1 with a plurality of interchangeable sets of lenses constituting the other of said stationary components and the other of said axially shiftable components, said interchangeable sets complementing said lenses L 6 - L 11 to a varifocal objective with different ratios of maximum to minimum overall focal lengths.

Claim 5

The combination deffined in claim 3 wherein said ratios are approximately 4:1, 6:1, 8:1 and 10:1.

Claim 6

In combination, a lens assembly as defined in claim 1 and a set of lenses comprising first, second and third lens members L 1 , L 2 , L 3 constituting the other of said stationary components and fourth and fifth lens members L 4 , L 5 '+L 5 " constituting the other of said axially shiftable components, said lens members L 1 - L 5 " having radii of curvature r 1 ' - r 5 ", axial thicknesses d 1 - d 5 ", refractive indices n d and Abbe numbers ν d substantially as given in the following table along with air spaces s 1 , s 2 separating said lens members L 1 , L 2 , L 3 , an air space s 4 separating said lens members L 4 , L 5 '+L 5 " and the sum of air spaces s 3 +s 5 +s 6 separating said stationary and axially shiftable components: ______________________________________ n.sub.d ν.sub.d ______________________________________ r.sub.1 ' = +3.10 L.sub.1 d.sub.1 = 0.08 1.81 25 r.sub.1 " = +1.50 s.sub.1 = 0.08 r.sub.2 ' = +1.62 L.sub.2 d.sub.2 = 0.25 1.60 61 r.sub.2 " = ∞ s.sub.2 = 0.01 r.sub.3 ' = +1.62 L.sub.3 d.sub.3 = 0.25 1.60 60 r.sub.3 " = ∞ r.sub.4 ' = +3.76 L.sub.4 d.sub.4 = 0.05 1.71 54 r.sub.4 " = +0.57 s.sub.4 = 0.17 r.sub.5 ' = -0.72 L.sub.5 ' d.sub. 5 ' = 0.05 1.62 53 r.sub.5 = +0.88 L.sub.5 " d.sub.5 " = 0.13 1.81 25 r.sub.5 " = -6.45 s.sub.3 + s.sub.5 + s.sub.6 = 1.11 ______________________________________

Claim 7

In combination, a lens assembly as defined in claim 1 and a set of lenses comprising first, second and third lens members L 1 '+L 1 ", L 2 , L 3 constituting the other of said stationary components and fourth and fifth lens members L 4 , L 5 '+L 5 " constituting the other of said axially shiftable components, said lens members L 1 ' - L 5 " having radii of curvature r 1 ' - r 5 ", axial thicknesses d 1 ' - d 5 ", refractive indices n d and Abbe numbers ν d substantially as given in the following table along with air spaces s 1 , s 2 separating said lens members L 1 '+L 1 ", L 2 , L 3 , an air space s 4 separating said lens members L 4 , L 5 '+L 5 " and the sum of air spaces s 3 +s 5 +s 6 separating said stationary and axially shiftable components: ______________________________________ n.sub.d ν.sub.d ______________________________________ r.sub.1 ' = +6.08 L.sub.1 ' d.sub.1 ' = 0.10 1.81 25 r.sub.1 = +1.92 L.sub.1 " d.sub.1 " = 0.37 1.62 60 r.sub.1 " = ∞ s.sub.1 = 0.01 r.sub.2 ' = +2.69 L.sub.2 d.sub.2 = 0.10 1.66 51 r.sub.2 " = +4.94 s.sub.2 = 0.01 r.sub.3 ' = +1.84 L.sub.3 d.sub.3 = 0.22 1.66 51 r.sub.3 " = +8.55 r.sub.4 ' = +6.65 L.sub.4 d.sub.4 = 0.05 1.69 55 r.sub.4 " = +0.56 s.sub.4 = 0.22 r.sub.5 ' = -0.96 L.sub.5 ' d.sub.5 ' = 0.05 1.62 60 r.sub.5 = +0.82 L.sub.5 " d.sub.5 " = 0.15 1.81 25 r.sub.5 " = +16.32 s.sub.3 + s.sub.5 + s.sub.6 = 1.32 ______________________________________

Claim 8

In combination, a lens assembly as defined in claim 1 and a set of lenses comprising first, second and third lens members L 1 '+L 1 ", L 2 , L 3 constituting the other of said stationary components and fourth and fifth lens members L 4 , L 5 '+L 5 " constituting the other of said axially shiftable components, said lens members L 1 ' - L 5 " having radii of curvature r 1 ' - r 5 ", axial thicknesses d 1 ' - d 5 ", refractive indices n d and Abbe numbers ν d substantially as given in the following table along with air spaces s 1 , s 2 separating said lens members L 1 "+L 1 ", L 2 , L 3 , an air space s 4 separating said lens members L 4 , L 5 '+L 5 " and the sum of air spaces s 3 +s 5 +s 6 separating said stationary and axially shiftable components: ______________________________________ n.sub.d ν.sub.d ______________________________________ r.sub.1 ' = +6.30 L.sub.1 ' d.sub.1 ' = 0.10 1.81 25 r.sub.1 = +1.99 L.sub.1 " d.sub.1 " = 0.38 1.62 60.3 r.sub.1 " = ∞ s.sub.1 = 0.01 r.sub.2 ' = +2.79 L.sub.2 d.sub.2 = 0.13 1.66 51 r.sub.2 " = +5.12 s.sub.2 = 0.01 r.sub.3 ' = +1.91 L.sub.3 d.sub.3 = 0.25 1.66 51 r.sub.3 " = +8.87 r.sub.4 ' = +6.21 L.sub.4 d.sub.4 = 0.05 1.69 55 r.sub.4 " = +0.52 s.sub.4 = 0.20 r.sub.5 ' = -0.89 L.sub.5 ' d.sub.5 ' = 0.05 1.62 60 r.sub.5 = +0.76 L.sub.5 " d.sub.5 " = 0.14 1.81 25 r.sub.5 " = +15.59 s.sub.3 + s.sub.5 + s.sub.6 = 1.46 ______________________________________

Claim 9

In combination, a lens assembly as defined in claim 1 and a set of lenses comprising first, second and third lens members L 1 '+L 1 ", L 2 , L 3 constituting the other of said stationary components and fourth and fifth lens members L 4 , L 5 '+L 5 " constituting the other of said axially shiftable components, said lens members L 1 ' - L 5" having radii of curvature r 1 ' - r 5 ", axial thicknesses d 1 ' - d 5 ", refractive indices n d and Abbe numbers ν d substantially as given in the following table along with air spaces s 1 , s 2 separating said lens members L 1 '+L 1 "L 2 , L 3 an air space s 4 separating said lens members L 4 , L 5 '+L 5 " and the sum of air spaces s 3 +s 5 +s 6 separating sai stationary and axially shiftable components: ______________________________________ n.sub.d ν.sub.d ______________________________________ r.sub.1 ' = 6.03 L.sub.1 ' d.sub.1 ' = 0.12 1.81 25 r.sub.1 = 1.99 L.sub.1 " d.sub.1 " = 0.48 1.62 60 r.sub.1 " = ∞ s.sub.1 = 0.01 r.sub.2 ' = 2.92 L.sub.2 d.sub.2 = 0.16 1.65 51 r.sub.2 " = 6.17 s.sub.2 = 0.01 r.sub.3 ' = 2.09 L.sub.3 d.sub.3 = 0.32 1.66 51 r.sub.3 " = 10.37 r.sub.4 ' = 6.98 L.sub.4 d.sub.4 = 0.05 1.69 55 r.sub.4 " = 0.52 s.sub.4 = 0.22 r.sub.5 ' = -0.88 L.sub.5 ' d.sub.5 ' = 0.05 1.62 60 r.sub.5 = 0.75 L.sub.5 " d.sub.5 " = 0.17 1.81 25 r.sub.5 " = 24.62 s.sub.3 - s.sub.5 - s.sub.6 = 1.50 ______________________________________