Lens barrel with collapsible lens groups, and image pickup apparatus

An image pickup apparatus with a lens barrel, wherein the lens barrel comprises:

• a first holding member of an inserted lens group that holds an inserted lens;
• a cam cylinder configured to drive the first holding member in a direction of an optical axis by a cam mechanism;
• and
• a second holding member of a retracting lens group located immediately adjacent to the inserted lens group along the optical axis, and configured to hold a retracting lens disposed closer to an image plane than the inserted lens,
• wherein at a shooting position, said second holding member is configured to lie on the optical axis, and during a process of retracting, said second holding member retracts to a retracted position away from the optical axis in a direction perpendicular to the optical axis in response to movement of said cam cylinder toward the image plane, and
• wherein a cam groove is formed on the cam cylinder, said groove is configured to move the first holding member in a direction toward a subject relatively to the cam cylinder so that the first holding member does not interfere with said second holding member during a process of retracting the lens barrel from a WIDE position to the collapsed position before said second holding member starts retracting to the retracted position as part of the process of retracting the lens barrel from the WIDE position to the collapsed position.