Patent ID: 8570663

Claim:
A zoom lens comprising, in order from an object side to an image side, a first lens unit of a positive refractive power, a second lens unit of a negative refractive power, a third lens unit of a positive refractive power, and a fourth lens unit of a positive refractive power, wherein the first lens unit does not move for zooming, at least the second and fourth lens units are moved during zooming, the first lens unit includes at least one positive lens 1 i , and the following conditions are satisfied: 0.5826 <θgF 1 i+ 0.001618×(ν d 1 i× 36.23)<0.8000, 0.040<√(| f 2 |×m 2)/ ft< 0.095, and 1.90 <n 2 na< 2.50, where νd 1 i and θgF 1 i denote an Abbe number and a relative partial dispersion, respectively, of a material of the positive lens 1 i , n 2 na denotes an average refractive index of materials of negative lenses included in the second lens unit, m 2 denotes a movement amount of the second lens unit for zooming from a wide-angle end to a telephoto end, f 2 denotes a focal length of the second lens unit, and ft denotes a focal length of the entire zoom lens at the telephoto end.