Most of Canon's cameras offer viewfinder diopter correction. Diopter correction is how your eye doctor dials in your glasses prescription (+ plus for farsightedness) and (- minus for nearsightedness). So you can see clearly with your glasses on. The viewfinder offers such correction without you having to wear glasses. But the camera's diopter correction has limits. It can't correct for a strong glasses prescription or other eye conditions.
-Demetrius
Bodies: EOS 5D Mark IV
Lenses: EF Holy Trinity, EF 85mm F/1.8 USM
Speedlites: 420EX, 470EX-AI, 550EX & 600EX II-RT
