Patent ID: 7903345
Filing Date: 2011-03-08
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 and configured to move during zooming; a third lens unit having a positive refractive power and configured to move during zooming; and a fourth lens unit having a positive refractive power and configured not to move for zooming, wherein the second lens unit includes at least one positive lens and at least one negative lens, and wherein average values of Abbe number (ν) and relative partial dispersion (θ) of materials of the at least one negative lens (νna, θna) and average values of Abbe number (ν) and relative partial dispersion (θ) of materials of the at least one positive lens (νpa, θpa) satisfy the following condition: