Patent ID: 9151938
Filing Date: 2015-10-06
Classification: G02B

Abstract:
1. A zoom lens, comprising, in order from an object side to an image side: a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a positive refractive power; and a fourth lens unit having a positive refractive power, wherein intervals between adjacent lens units vary during zooming, and the first lens unit moves so as to be disposed nearer to an object at a telephoto end than at a wide angle end, and wherein each of the first lens unit to the fourth lens unit has at least one negative lens, and conditional expressions are satisfied where Lt is a lens total length at the telephoto end, ft is a focal length of an entire system at the telephoto end, N2an is a mean value of refractive indices of materials of negative lenses included in the second lens unit, NAan is a mean value of refractive indices of materials of negative lenses included in the entire system, and NAap is a mean value of refractive indices of materials of positive lenses included in the entire system.