Patent ID: 8488253
Filing Date: 2013-07-16
Classification: G02B

Abstract:
1. A zoom lens, comprising, in order from an object side: a first lens unit having positive refractive power which does not move for varying magnification; a magnification-varying lens unit including at least two lens units which move for varying magnification; an aperture stop; and an imaging lens unit having positive refractive power which does not move for varying magnification, wherein: the first lens unit includes, in order from the object side, a first sub-lens unit having positive refractive power, a second sub-lens unit having negative refractive power, and a third sub-lens unit having positive refractive power; the third sub-lens unit includes a movable sub-third sub-lens unit having positive refractive power; the second sub-lens unit and the sub-third sub-lens unit are respectively driven to the object side so as to perform focus adjustment to an object at a short distance; and the following expressions are satisfied: where f12 represents a focal length of the second sub-lens unit, f13f represents a focal length of the sub-third sub-lens unit, δ×12 represents a drive amount of the second sub-lens unit in focus adjustment, and δ×13f represents a drive amount of the sub-third sub-lens unit in focus adjustment.