<p>I agree with Don. I've got old Nikon cameras, Canon cameras, and Leica's. Canon and Nikon do their diopter ratings the same way, Leica does theirs different. So I use a "0" on both Nikon and Canon, and a "+1" with the Leica.</p>
<p>It really helps to try the group of diopters that are in your range, like for me with Nikon it would be "+0.5", "0", and "-0.5". The image really "Pops" when you hit the right diopter for your vision.</p>
<p>Best,<br>
-Tim</p>