Optical apparatus and image pickup apparatus

An image pickup apparatus comprising:

• an optical apparatus;
• and
• an image pickup element configured to pick up an image formed by the optical apparatus,
• wherein the optical apparatus comprising:
• a fixed barrel;
• a movable barrel disposed inside the fixed barrel and holding an optical element;
• a mechanism configured to move the movable barrel along an optical axis by rotation of the movable barrel around the optical axis;
• and
• an operating member disposed through the fixed barrel and rotationally operated,
• wherein the operating member comprises a rotating shaft and an engaging portion eccentric from the rotating shaft, the rotating shaft being rotated with the operating member being rotationally operated, the engaging portion being engaged with a guide formed in the movable barrel along the optical axis;
• at least a part of the engaging portion is located outside the rotating shaft in a direction orthogonal to the rotating shaft;
• rotation of the operating member causes the engaging portion to slide on the guide, the movable barrel to rotate around the optical axis, and the mechanism to move the movable barrel along the optical axis.