Optical viewfinder

An optical viewfinder configured to be attached to a camera body with an interchangeable lens, the optical viewfinder comprising:

• a Keplerian viewfinder optical system including a scalable objective lens group;
• a drive source configured to drive at least one objective lens of the objective lens group along an optical axis;
• a detector configured to detect a position of the at least one objective lens;
• a control circuit configured to control driving of the drive source based on a result of detection by the detector;
• an electric contact configured to be electrically coupled to the camera body;
• a visual field frame disposed on a focal plane of the objective lens group, the visual field frame having an opening wider than a photographing frame of the interchangeable lens that is to be attached to the camera body;
• and
• a display device optically equivalent to the focal plane when viewed from an eyepiece lens of the camera and located at a position different from that of the visual field frame, wherein
• when a variable focal length lens is attached to the camera body as the interchangeable lens, the control circuit controls driving of the drive source to adjust a magnification of the objective lens group and displays at least the photographing frame on the display device, based on information on a focal length of the variable focal length lens received from the camera body through the electric contact.