Trying to identify the thread on a microscope eyepiece, it has no makers or other marks on it. The outside diameter of the male thread measures 26.7mm or 1.050 inches. The pitch is not easy to measure but looks like 0.5mm or about 50 tpi.
Standard lens type threads are M25 or M26 or SM1 (26.3mm, 1.035”) so it does not seem to fit with those.
Has anyone come across this size before?