Zoom lens
AssigneeVivitar Corporation
InventorEllis Betensky
Life of this patent
Estimating the term…
Abstract
An improved optical system for a relatively compact zoom lens of relatively high speed, moderate range, and extending from normal into the telephoto region, the lens being of simple construction and having two lens groups and as few as six elements.
Claims14
A zoom lens having upper and lower limit equivalent focal lengths comprising from the object end, a first negative group and a second positive group, said groups being movable axially relative to each other to vary the equivalent focal length of the lens, the absolute value of the equivalent focal length of said first group .vertline.F.sub.1 .vertline. being greater than the lower limit equivalent focal length of said lens, and
- 3>.vertline.F.sub.1 .vertline./F.sub.2 .gtoreq.1.6
- where F.sub.2 is the equivalent focal length of said second group, the lower limit equivalent focal length of said lens being greater than the diagonal of the image frame of said lens, said first group consists of two elements, one of which is biconcave.
Dependencies are inferred from the claim text.