I have an H Alpha modified Canon M200.
With a Canon autofocus lens, it could reach infinity focus, but with a Rokinon manual focus, it could not.
Unfortunately, this Rokinon lens doesn’t have a rubber grip ring to move out of the way and likewise there are no screws for adjusting infinity focus.
I was able to achieve infinity focus with an easy kluge-y cheat: I added a 1.25 inch Astromania UV-IR cut filter onto the back of the lens. A few drops of slightly rubbery hot melt glue holds the filter in place.
The 1.25 inch filter cell allowed the filter to be placed flat and normal to the focal axis without disturbing the rear lens element and without sticking back too far and hitting the sensor. The 1.25 inch filter is large enough so I don’t get any vignetting. Nor does it cause chromatic aberration.
The thickness of the flat filter was sufficient to move the focal point back far enough to reach infinity and still have some focusing margin.
Edited by KLWalsh, 09 September 2024 - 06:10 AM.