Patent ID: 7586682
Filing Date: 2009-09-08
Classification: G02B

Abstract:
1. A zoom lens comprising: a varifocal lens unit having a plurality of movable lens groups, and a prism disposed on an image side of the varifocal lens unit, wherein the prism has an incident plane on which a light flux from the varifocal lens unit enters, and an exit plane from which the light flux is emitted toward an image plane, and is configured such that the incident plane or the exit plane or both planes can be inclined with respect to an optical axis, whereby a field of view is shifted by a predetermined amount by inclining the plane; wherein the varifocal lens unit includes a front side lens group, an aperture diaphragm and a rear side lens group, which are arranged in order from an object side, and following conditional expressions (1) and (2) are satisfied: where φb: refractive power of the rear side lens group in a wide angle end, φ: refractive power of whole zoom lens in the wide angle end, Bf: distance from the exit plane to the image plane of the prism in a telephoto end along the optical axis, FNO: F number in the telephoto end for the entire varifocal lens unit, Ymax: maximum image height, and Bf and Ymax have the same units of measure.