Optically, How do the Zuiko 21mm f3.5 and f2.0's compare with the RF ones (Leica 21mm f3.4, Zeiss 21mm f2.8, CV 21mm f4.0)? The Zuiko wides are good, but are they that good? SLR lenses are usually compared to SLR lenses for obvious reasons. I know this is apples and oranges but I see pros and cons for both setups as well.