Nikon 10 diopter eyepiece correction for d90 d3100 d7000 d300s f80 d100 d300 d80 d60 and d40 the the nikon eyepiece diopters allow you to optimise your slr viewfinders sharpness in conjunction with your individual eyesight eyepiece diopters are designed for specific camera models and are identified by a plus a minus or a neutral numeric diopter value