This is a brand new, professional designed C-mount adapter/converter for Olympus BX Bayonet mount trinocular microscopes! After mounting the adapter to the top of the trinocular microscope, and the other end has c-mount thread for attaching standard c-mount cameras, adapter for micro-photography! Figure(1) The converter bottom view, showing the bayonet mount; (2) the converter top view, showing the C-mount; This is a mechanical adapter that includes NO optical reduction lens within the assemblys! This adapter is compatible to the following OLYMPUS microscopes: Upright: AX Provis Series BX Series CX Series CX2 Series MX Series (ALL w/ U-SPT phototube removed) BX U-DPT Double Port (back por) STEREO: SZX Series (ALL w/ U-SPT phototube removed) What is a "C-mount"? A C-mount is a type of lens mount commonly found on 16mm movie cameras, closed-circuit television cameras, and trinocular microscope phototubes. C-mount lenses provide a male thread which mates with a female thread on the camera. The thread is nominally 1 inch in diameter, with 32 threads per inch, designated as "1-32 UN 2A" in the ANSI B1.1 standard for unified screw threads. The register (distance from the lens mount flange to the focal plane) is 17.526 mm (0.69 inches) for a C-mount, 12.52 mm for the otherwise identical CS-mount. The letter "C" is said to stand for "cine", the original application being movie camera lenses. What is "Bayonet mount"? A bayonet mount or bayonet connector is a fastening mechanism consisting of a male side with one or more pins, and a female receptor with matching "L" slots and spring(s) to keep the two parts locked together.