EOS-T2 Adapter for ZWO ASI cameras

thingiverse

When I purchased an ZWO ASI183MC camera to use with my Sigma 150-600mm f/5.6-6.3 Contemporary lens, I was disappointed to find that the required EOS to T2 adapter that ZWO makes was out of stock on High Point Scientifics website, therefore I decided to model and 3D print my own. After numerous prototypes and much wasted plastic I finally have what I've believe a working version. _A standard 2" astronomy filter is capable of being threaded into this adapter_. This adapter has a total height of 37.5mm which I calculated from the fact that the ASI183MC has an 11mm depth T2 ring already on it + the total depth of the ZWO EOS adapter is 26.5mm front to back. This adapter screws directly onto the M42 threads of the camera body and does not utilize the included Male-Female T2 ring. You may have to use the included Teflon spacer shims that come with the ASI cameras to get the threads to tighten at the right point such that the ZWO camera sensor is aligned 90/180 degrees with the focal axis of the lens, otherwise you will have image rotation. It took me a long time to get the dimensions of the standard Canon EF mount to be correct such that they grip the lens mount perfectly, while this doesn't have a spring-loaded retaining pin like actually mounts do, the friction alone holds the lens and camera together just fine in my testing. The ring groove in the mating face of this adapter is intended to hold O-ring cord to create a somewhat air/water tight seal against the lens, I specifically used 1/16" diameter Soft Buna-N O-Ring Cord Stock: https://www.mcmaster.com/9864K23/ As visualized by the included image of the star Capella whilst using a Bahtinov mask, at 600mm focal length this adapter does indeed allow proper focusing of the optics. _I will disclose however I haven't tested it with any other lens other than the Sigma 150-600mm_.