These are the modified version of the original adjustable viewfinder magnifier. The type Y has a magnification range from 1.15x to 1.65x or equal to -150 to +350 diopter . Whereas the Type J magnifier has a magnification range from 1x to 1.5x or equal to -250 to +250 diopter.
Multi-coated lens glasses for anti-reflective
Dampening the zoom ring for proper stiffness
Up to 1.65x magnification
Easy to install, simply screw into the viewfinder ocular