Spent 6 months cleaning viewfinder glass with the wrong cloth before a customer pointed it out
A guy dropped off his Nikon F3 in January and watched me wipe the eyepiece with a microfiber that had a grain of grit stuck in it, and he asked if I always scratch glass like that, which is when I switched to a lens pen and air blower and stopped making things worse, so what do you all use on viewfinder glass that actually leaves it clean?