Rear conversion lens
AssigneeNippon Kogaku K.K.
InventorsYoshinari Hamanishi, Soichi Nakamura
Life of this patent
Estimating the term…
Abstract
A rear conversion lens comprises a divergent forward lens group comprising three components and a divergent rearward lens group comprising two components. The three components forming the forward lens group are, in order from the object side, a biconvex positive lens, a biconcave negative lens with its more curved surface facing the image side, and a positive lens with its more curved surface facing the object side. The two components forming the rearward lens group are, in order from the object side, a biconcave negative lens with its more curved surface facing the image side and a biconvex positive lens with its more curved surface facing the object side.
Claims5
A rear conversion lens mountable to the image side of a photographic lens to make the composite focal length of the rear conversion lens and the photographic lens greater than the focal length of the photographic lens, comprising:
- a divergent forward lens group comprising three components which are, in order from the object side, a biconvex positive lens, a biconcave negative lens with its more curved surface facing the image side, and a positive lens with its more curved surface facing the object side;
- and
- a divergent rearward lens group disposed on the image side of said forward lens group and comprising two components which are, in order from the object side, a biconcave negative lens with its more curved surface facing the image side and a biconvex positive lens with its more curved surface facing the object side.
Dependencies are inferred from the claim text.