While early Leica RFs have a diopter adjustment around the viewing eyepiece or the rewind knob, knob wind Canon RFs seem to have opted for their innovative three-position viewfinder. I'm not aware of any knob-wind Canon RF that has diopter adjustment -- can anyone set me straight? This is important to me because I really rely on the diopter adjustment on my Leica III to be able to properly see the focus spot and image. If a knob-wind Canon is equivalent in viewing terms to my IIIc with the dioper unadjusted, then I guess I should pass on buying one. Thought? Thanks!