Patent ID: 7423687

Claim:
An image-taking lens system comprising: a relay lens unit having an image-forming action; a wobbling lens unit arranged within the relay lens unit, the wobbling lens unit being driven by an amplitude in an optical axis direction; and an auxiliary lens system which can be inserted into and removed from the relay lens unit, the auxiliary lens system shifting a focal length of the overall image-taking lens system, wherein an amplitude amount of the wobbling lens unit is set on the basis of a state regarding whether the auxiliary lens system is inserted or removed, and wherein the wobbling lens unit is arranged further to the object side than the auxiliary lens system, and the amplitude amount of the wobbling lens unit satisfies the following expression: W IN = δ · F K 2 ⁢ W OUT where δ: a change magnification of diameter of permissible circle of confusion when exchanging a main body of an image-taking apparatus; F: a change magnification of effective F number when the auxiliary lens system is inserted or removed; K: a shift magnification of focal length when the auxiliary lens system is inserted or removed; W IN : an amplitude of wobbling lens unit when the auxiliary lens system is inserted; and W OUT : an amplitude of wobbling lens unit when the auxiliary lens system is removed.