Variable focal lens having a divergent front element

Claim 2

A lens whose focal length is variable in about the double range, consisting of a front lens element (A) facing the longer beam length and having divergent refractive power, a lens component (B) displaceable over the airspace following thereon and having positive refractive power, and a basic objective (C) having positive refractive power, the lens components being constructed as follows: (a) the divergent front lens element contains a concavity facing in the direction of the shorter beam length of the lens; (b) the displaceable convergent lens component following thereon comprises at least a divergent meniscus facing the front element and a convergent glass whose more sharply curved surface faces the front element; (c) the basic objective consists of a fixed part, and a movable part having negative refractive power and which through the shape of its outer surfaces constitutes a meniscus curved in the direction of the front lens element, and at least a convergent glass and a biconcave glass facing the shorter beam length; (d) the displacement of the movable part of the basic objective amounts to only a fraction of that of the convergent lens component (B), and the two movable parts are coupled together in such a manner that this displacement takes place in the same direction; (e) the fixed part of the basic objective has a convergent action and its more sharply curved outer surface faces the shorter beam length.

Claim 3

A lens according to claim 1, wherein the v value of the divergent glass of the moveable convergent lens component (B) is lower than that of the convergent lens element following thereon.

Claim 4

A lens according to claim 1, wherein the v value of the convergent glass of the moveable part of the basic objective is higher than that of the divergent glass following thereon.

Claim 5

A lens according to claim 1, wherein the constructional data corresponds substantially to the following: ______________________________________ r.sub.1 = - 800 L.sub.1 d.sub.1 = 2.0 1.51680 64.2 r.sub.2 = + 112.6 1.sub.1 = 0.5-72.5 r.sub.3 = + 96.0 L.sub.2 d.sub.2 = 1.8 1.69761 38.6 r.sub.4 = + 40.0 1.sub.2 = 0.05 r.sub.5 = + 40.35 L.sub.3 d.sub.3 = 6.0 1.68900 49.5 r.sub.6 = - 305.0 1.sub.3 = 65.0-0.5 r.sub.7 = + 40.0 L.sub.4 d.sub.4 = 10.0 1.57309 42.6 r.sub.8 = - 36.8 L.sub.5 d.sub.5 = 8.5 1.72047 34.6 r.sub.9 = + 36.0 1.sub.4 = 21.0-13.5 r.sub.10 = - 1600.0 L.sub.6 d.sub.6 = 4.5 1.65160 58.5 r.sub.11 = - 43.4 ______________________________________

Claim 6

A lens according to claim 1, wherein the constructional data corresponds substantially to the following: ______________________________________ r.sub.1 = - 1000.0 L.sub.1 d.sub.1 = 2.0 1.51680 64.2 r.sub.2 = + 110.4 1.sub.1 = 0.5-72.5 r.sub.3 = + 91.0 L.sub.2 d.sub.2 = 1.8 1.72373 36.1 r.sub.4 = + 35.7 1.sub.2 = 0 Cemented r.sub.5 = + 35.7 L.sub.3 d.sub.3 = 6.0 1.68900 49.5 r.sub.6 = - 308.0 1.sub.3 = 67.5-0.5 r.sub.7 = + 40.83 L.sub.4 d.sub.4 = 12.0 1.68273 44.5 r.sub.8 = + 375.0 1.sub.4 = 1.7 r.sub.9 = - 83.0 L.sub.5 d.sub.5 = 3.5 1.68893 31.2 r.sub.10 = + 35.1 1.sub.5 = 18.0-13.0 r.sub.11 = + 2400.0 L.sub.6 d.sub.6 = 5.0 1.65160 58.5 r.sub.12 = - 40.16 ______________________________________

Claim 7

A lens according to claim 1, wherein the constructional data corresponds substantially to the following: ______________________________________ r.sub.1 = - 800.0 L.sub.1 d.sub.1 = 2.0 1.516680 64.2 r.sub.2 = + 112.6 1.sub.1 = 0.5-72.5 r.sub.3 = + 96.0 L.sub.2 d.sub.2 = 1.8 1.69761 38.6 r.sub.4 = + 40.0 1.sub.2 = 0.05 r.sub.5 = + 4.45 L.sub.3 d.sub.3 = 6.0 1.68900 49.5 r.sub.6 = - 300.0 1.sub.3 = 67.5-0.5 r.sub.7 = + 40.0 L.sub.4 d.sub.4 = 12.5 1.67003 47.1 r.sub.8 = + 346.0 1.sub.4 = 1.4 r.sub.9 = - 85.75 L.sub.5 d.sub.5 = 4.0 1.68893 31.2 r.sub.10 = + 34.65 1.sub.5 = 18.0-13.0 r.sub.11 = + 2300.0 L.sub.6 d.sub.6 = 5.0 1.65160 58.5 r.sub.12 = - 40.18 ______________________________________