This SLR Camera Adapter for Canon auto-focus 35mm and digital EOS SLR cameras with its large 1.875" (47.6 mm) inside diameter EOS bayonet minimizes vignetting on full frame chips and on 35 mm film by eliminating the restrictive 1.5” (38 mm) diameter standard T-thread interface. Since the introduction of Canon’s full 35 mm frame digital SLR’s, people have been asking for a solution to the vignetting caused by the small clear aperture of the standard T-ring interface that is universally used to connect telescopes to SLR cameras. This was especially true for Astro-Physics telescope owners who also had either our 2.7” or 4” Field Flatteners. What good were pinpoint stars to the edge of a wide field when the edge of that field was darkened by the T-ring’s vignetting effect? So, in keeping with our commitment to imagers, we introduced a solution!
The adapter body is precision-machined aluminum and is anodized black. The bayonet is machined stainless steel, and both the body and the bayonet are baffled and painted flat black on the inside. The adapter is intended to be used exclusively with Astro-Physics 2.7" and 4" Prime Focus Field Flatteners (except the 160FF). It will position the chip (or film) at the correct distance from the Field Flattener optics for pinpoint stars. If you received your 2.7" Field Flattener prior to May 1994, you will need new aluminum parts to use this adapter.
Please note: this adapter can NOT be used with Canon manual-focus 35mm cameras (series FD and earlier lenses).