Photo ring / adapter for 2 "GSO projection glasses. It allows the transition from the eyepiece to the M52x0.75 thread connecting the camera with a lens with a 52 mm filter thread (popular standard, 52 mm filter reductions available from photo stores).
The connector allows you to put together a set for shooting: projection eyepiece - camera with 52 mm lens; it is worth considering that we get the finally modified magnification resulting from the focal length of the camera lens.
• camera side thread: M52x0.75 male
• eyepiece thread: M57x0.75 female