Zoom lens and image pickup apparatus including the same

摘要

A zoom lens includes, in order from an object side: a positive first lens unit that does not move for zooming and comprises a negative first sub-lens unit, a positive second sub-lens unit that moves during adjustment of a focal point, and a positive third sub-lens unit composed of at least one negative lens, and at least two positive lenses; a lens group including at least two lens units that move during zooming; an aperture stop; and a positive last lens unit that does not move for zooming. Focal lengths of the first lens unit, the first sub-lens unit, and the zoom lens at a wide angle end, imaging magnification of the last lens unit, average values of an Abbe constant for d-line of the at least one negative lens and of the at least two positive lenses are appropriately set.

主权项

1. A zoom lens, comprising, in order from an object side to an image side:
a first lens unit having a positive refractive power that does not move for zooming, the first lens unit comprising a first sub-lens unit having a negative refractive power, a second sub-lens unit having a positive refractive power that moves during adjustment of a focal point, and a third sub-lens unit having a positive refractive power; a lens group including at least two lens units that move during zooming; an aperture stop; and a last lens unit having a positive refractive power that does not move for zooming, wherein the following conditional expressions are satisfied:
2.6 wherein the third sub-lens unit comprises at least one negative lens, and at least two positive lenses, wherein the following conditional expression is satisfied:
2.0<ν13pa/ν13na<5.8where ν13na denotes an average value of an Abbe constant with a d-line as a reference of the at least one negative lens, and ν13pa denotes an average value of Abbe constants with the d-line as the reference of the positive lenses, and
wherein an Abbe constant νd with the d-line as the reference is defined by the following equation,
νd=(nd−1)/(nF−nC)where nd denotes a refractive index in the d-line, nC denotes a refractive index in a C-line, and nF denotes a refractive index in an F-line.