Patent ID: 7339747
Filing Date: 2008-03-04
Classification: G02B

Abstract:
1. A variable magnification optical system for forming an optical image of an object on a light receiving surface of an image sensor so that a magnification is variable, said variable magnification optical system comprising from an object side: a first lens unit having negative optical power; a second lens unit having positive optical power; a third lens unit having positive optical power; and a fourth lens unit having positive or negative optical power, said fourth lens unit consisting of a single lens element having optical power, said single lens element comprising an optical member having a wavelength selecting property, wherein an object side surface of the single lens element has the wavelength selecting property, and an image side surface of the single lens element is a lens surface having a higher curvature than the object side surface, wherein in magnification variation from a wide-angle end to a telephoto end, at least the first lens unit and the second lens unit are movable and the fourth lens unit is stationary.