US 4,286,847 A · Lightweight inverted telephoto type wide angle lens system

Abstract

The present invention is directed to an inverted telephoto type wide angle lens system having eight lens groups and eight lens elements which fulfill the following conditions: ______________________________________ 0.75f < .vertline.f.sub.1,2,3 .vertline. < 1.1f f.sub.1,2,3 < 0 0.89f < f.sub.1,2,3,4,5 < 2.3f 0.5 < d.sub.7 /d.sub.6 < 2.0 1.0 < d.sub.8 /d.sub.10 < 2.4 1.5 < d.sub.7 /d.sub.9 < 5.2 ______________________________________ wherein f.sub.1,2,3 represents the total focal length of the first to third single lens elements; f.sub.1,2,3,4,5 represents the total focal length of the first to fifth single lens elements; f represents the focal length of the entire lens system, and d.sub.i represents the i-th axial distance numbered consecutively from the front of the lens system.

Claims10

Dependent claims

An compact lightweight telephoto type wide angle lens system having eight lens groups and eight lens elements comprising from the object to the image side:

a first lens group consisting of a first positive single lens element;
a second lens group consisting of a second negative meniscus single lens element convex to the object side;
a third lens group constituting of a third negative meniscus single lens element convex to the object side;
a fourth lens group consisting of a fourth positive single lens element;
a fifth lens group consisting of a fifth biconvex single lens element;
a sixth lens group consisting of a sixth biconcave single lens element;
a seventh lens group consisting of a positive meniscus single lens element convex to the image side, and
an eighth lens group consisting of an eighth positive single lens element, in which the lens system fulfills the following conditions:
______________________________________ 0.75f <
.vertline.f.sub.1,2,3 .vertline. <
1.1f f.sub.1,2,3 <
0 0.89f <
f.sub.1,2,3,4,5 <
2.3f 0.5 <
d.sub.7 /d.sub.6 <
2.0 1.0 <
d.sub.8 /d.sub.10 <
2.4 ______________________________________
wherein;
f.sub.1,2,3 represents the total focal length of the first to third single lens element;
f.sub.1,2,3,4,5 represents the total focal length of the first to fifth single lens element;
f represents the focal length of the entire lens system, and
d.sub.i represents the i-th axial distance numbered consecutively from the front of the lens system.

20 more elements

Dependencies are inferred from the claim text.

Lightweight inverted telephoto type wide angle lens system

Life of this patent

Lightweight inverted telephoto type wide angle lens system

Life of this patent

Abstract

Claims10