Patent ID: 8102605
Filing Date: 2012-01-24
Classification: G02B

Abstract:
1. A zoom lens comprising: 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 the first, second, third and fourth lens units are arranged in order from the object side to the image side, respectively, wherein distances between the lens units are changed during zooming, wherein the first lens unit is composed of a cemented lens including a first lens having a negative refractive power and a second lens having a positive refractive power arranged in order from the object side to the image side, and wherein, when Nd1a and νd1a are a refractive index and an Abbe number, respectively, of a material of the first lens for a d-line, the following conditions are satisfied: wherein, when m