small zoom lens

Abstract

Abstract PURPOSE:To obtain a small zoom lens having high optical performance in the whole variable power range and shortening the whole length by constituting the lens system of seven lenses in two groups and satisfying specific conditions. CONSTITUTION:The lens system is constituted of a 1st group I consisting of a 1st positive lens, a 2nd negative lens and 3rd and 4th lenses both of which have convex faces on both sides and a 2nd group II consisting of a 5th positive lens, a 6th negative lens and a 7th negative lens. When it is defined that the focal distances of the 1st and 2nd groups are f1 and f2, the moving distance of the 1st lens group I from the wide angle end up to the telephoto end is M1, the moving distance of the 2nd lens group II from the wide angle end up to the telephoto end is M2, the focal distances of the whole system on the wide end and telephoto end are fw and ft, back focus values on the wide end and telephoto end are SKw and SKt, and the interval of the 1st and 2nd lenses on the telephoto end is Dt, the unequalities I to V are satisfied.

Inventors

• 👤 Yoshiaki Ito
• 👤 良紀 伊藤

Bibliographic Details