Patent ID: 7113344

Claim:
An anamorphic converter which can be inserted into and removed from a lens group of an image-formation optical system, the anamorphic converter comprising: an anamorphic lens satisfying the following conditions: 0.9<( AR 1·β x )/( AR 2·β y )<1.1 ( AR 2 2 +1)·β y 2 /( AR 1 2 +1)>1 wherein βx represents a first focal distance magnification scale at a first cross-section containing an optical axis of the anamorphic lens, wherein βy represents a second focal distance magnification scale at a second cross-section which is perpendicular to the first cross-section and contains the optical axis, wherein AR 1 represents an aspect ratio of an image-taking range in a field of the image-formation optical system, wherein AR 2 represents an aspect ratio at an effective range of an image-taking unit disposed at an object side of the lens group, wherein the anamorphic lens includes at least two anamorphic lenses at and a 1 and a 2 positioned in order from an image side, and satisfying the following conditions: φa1>0 φa2<0, and wherein φa 1 and φa 2 represent refractive flowers of the anamorphic lenses at and a 1 and a 2 , respectively, at least one of the first cross-section and the second cross-section.