This Pro Lens Mount Adapter from FotodioX allows you to mount your Canon EF lenses on a C-mount camera as well as on some microscope phototubes. The smaller imager associated with C-mounts means that you will be recording from the center of the lens, which tends to be the best part of the lens, optically speaking.
Even though Canon EOS lenses use an electronic aperture, which will not function with adapters, this adapter's built-in clickless iris allows you to use your lens with some exposure control. It can be used to shoot both in manual mode and in aperture-priority mode. Automatic diaphragm, auto-focusing, and other lens functions will not work correctly while using this adapter. Lens aperture cannot be controlled via the camera body, and "stop-down mode" will need to be used when metering.