Patent ID: 8988785
Filing Date: 2015-03-24
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, and a rear group including at least two lens units and having a positive refractive power as a whole in an entire zoom range, in order from an object side to an image side, wherein an interval of each of the lens units is configured to change in a zoom operation, the rear group includes a lens unit R having a positive refractive power at the most image side of the rear group, the lens unit R includes a lens having a concave surface at the image side and the concave surface having an aspherical surface shape where a negative refractive power becomes stronger with increasing distance from an optical axis, and the following conditional expressions are satisfied, where f1 is a focal length of the first lens unit, fR is a focal length of the lens unit R, fw is a focal length of a whole system at a wide-angle end, Na is a refractive index of a material of the lens of the aspherical surface shape, f2 is a focal length of the second lens unit, and ft is a focal length of a whole system at a telephoto end.