Patent ID: 8976271
Filing Date: 2015-03-10
Classification: G02B,H04N

Abstract:
1. An optical system capable of performing variation of magnification, the optical system comprising in order from an object side to an image side: a first lens unit; and a second lens unit, at least one of the first and second lens units being moved during the variation of magnification, wherein the optical system forms an optical image on an image sensor provided in an image pickup apparatus, and wherein the optical system satisfies the following conditions: where, when a middle focal length closer to a wide-angle end of the optical system than to a telephoto end thereof is referred to as a wide-angle side middle focal length, another middle focal length closer to the telephoto end than to the wide-angle end is referred to as a telephoto side middle focal length, an image height corresponding to 80 percent of a maximum image height of the optical system is referred to as an 80 percent image height, and, among meridional rays passing through the optical system, an upper ray and a lower lay each passing through a position corresponding to 70 percent of an effective light flux diameter are respectively referred to as a 70 percent upper ray and a 70 percent lower ray, ΔWMyu represents a lateral aberration amount for a d-line of the 70 percent upper ray reaching the 80 percent image height at the wide-angle side middle focal length, ΔWMyl represents a lateral aberration amount for the d-line of the 70 percent lower ray reaching the 80 percent image height at the wide-angle side middle focal length, ΔTMyu represents a lateral aberration amount for the d-line of the 70 percent upper ray reaching the 80 percent image height at the telephoto side middle focal length, ΔTMyl represents a lateral aberration amount for the d-line of the 70 percent lower ray reaching the 80 percent image height at the telephoto side middle focal length, P represents a pixel pitch of the image sensor, and when fw represents a focal length of the optical system at the wide-angle end, ft represents a focal length of the optical system at the telephoto end, and fm=√(fw×ft), the wide-angle side middle focal length fwm is expressed as fwm=√(fw×fm), and the telephoto side middle focal length ftm is expressed as ftm=√(fm×ft).