Patent ID: 7755855

Claim:
An extendable lens barrel comprising: a first group frame retaining a first group lens with a positive refractivity, and being movable in a direction of an optical axis; a second group frame retaining a second group lens with a negative refractivity at an imaging side of the first group lens on the optical axis and being movable in the direction of the optical axis; a third group frame retaining an aperture diaphragm and a third group lens with a positive refractivity, and being movable in the optical axis and pivotable in the direction perpendicular to the optical axis in such a manner that said aperture diaphragm and said third group lens can be positioned at the imaging side of the second group lens on the optical axis in a imaging standby state, and the aperture diaphragm and the third group lens are retracted to a position out of the optical axis, in the retracted state, in which the length of the lens barrel is shorter than that of in imaging standby state; a fourth group frame retaining a fourth group lens with a positive refractivity and being movable in the optical axis direction at the imaging side of the third group lens on the optical axis in the imaging standby state; and, said second group lens comprising at least two lenses, namely a second group object side lens and a second group imaging side lens having an outer shape smaller than that of the second group object side lens; said fourth group lens comprising lenses with an outer shapes smaller than that of the second group object side lens; said aperture diaphragm and said third group lens being so arranged to retract into the position between the object side end of the second group image side lens and the image side end of the fourth group lens.