Patent ID: 7190528
Filing Date: 2007-03-13
Classification: G02B

Abstract:
1. A zoom lens comprising: a plurality of lens units including a first lens unit disposed most adjacent to an enlargement side and having negative refractive power, wherein at least one of said plurality of lens units is moved in the direction of the optical axis thereof during magnification change; wherein said first lens unit includes a 1-1st lens unit comprising at least one lens having negative refractive power and moved during focusing; and a 1-2nd lens unit having positive refractive power and fixed during focusing; wherein said plurality of lens units include a last lens unit disposed most adjacent to a reduction side and having positive refractive power; wherein said 1-1st lens unit is disposed more adjacent to the enlargement side than said 1-2nd lens unit; and wherein a first lens of said first lens unit which is most adjacent to the enlargement side has negative refractive power, the last lens in said last lens unit which is disposed most adjacent to a reduction side has positive refractive power, and the following condition is satisfied, where νdF represents the Abbe number of the material of said first lens and νdR represents the Abbe number of the material of said last lens.