Abstract: An opto-mechanical coupler is described for providing a quick-release mechanical and optical connection between a camera and the eyepiece of an endoscope or other optical instrument. The coupler comprises a hollow body member that is adapted to be screwed into the threaded aperture of a camera and is characterized by a center bore for transmitting images from the endoscope to the camera, and eyepiece clamping means attached to the hollow body member.In one embodiment, the eyepiece clamping means comprises a single clamping member defining a channel for receiving the eyepiece, and means rotatably connecting the clamping means to the hollow body so that rotation of the clamping member in one direction will cause the eyepiece to be clamped to the hollow body and rotation in a second opposite direction will unclamp the eyepiece from the hollow body.