Did you know you can adjust your camera eyepiece (viewfinder diopter) on your camera for your vision? Adjust the dial (or slider) for your vision This has nothing to do with your autofocus lens, this is purely for your vision, to adjust it so that you can see clearly when you look through the viewfinder And if you like to focus your lens manually, it is imperative that this diopter is sharp - it’s a bit like when you put a pair of binoculars to your eyes and you adjust the middle dial to sharpen