Patent ID: 6952526

Claim:
A retractable barrel comprising: a rear holder configured to hold a rear optical element on an axis, said rear holder comprising a recess; an annular member movable along the axis towards and away from said rear holder without rotation; a retractable holder, accommodated within the annular member, configured to hold a retractable optical element, the retractable holder being movable between an aligned position where the retractable optical element is aligned with the axis, and a displaced position where the retractable optical element is displaced relative to the axis; and a position controller configured to control said annular member and retractable holder to move between an operational position spaced from said rear holder with said retractable holder at said aligned position to a retracted position where said rear optical element is accommodated within the inner peripheral surface of the annular member with said retractable holder at said displaced position and where a portion of said rear holder and a portion of said retractable holder are at the same position on said annular member axis; wherein a movement path of said retractable holder includes an oblique path extending obliquely to the axis; and wherein said recess configured to prevent said rear holder from interfering with said retractable holder as said retractable holder moves to and from the operational position and the retracted position.