A lens barrel including a telescopic cylinder configured to be
accommodated within a fixed cylinder; a plurality of lens groups
configured to be retained in the telescopic cylinder; a lens driving
device configured to drive the plurality of lens groups along a
longitudinal axis of the telescopic cylinder between a collapsed position
in which at least one portion of the plurality of lens groups is stored
in the fixed cylinder and an extended position in which the at least one
portion of the plurality of lens groups is extended out of the fixed
cylinder; and a retractable lens group configured to be retracted into
the fixed cylinder through an opening in a wall of the fixed cylinder
when the telescopic cylinder is in the extended position.