A new idea I came up with last night.. I have a Nikon F100 body. I've heard amazing things about the new Voigtlander 40/2 Ultron SL II. I'm wondering how this lens would compare to the Zeiss lenses. I've seen sharpness tests where it blows away Nikon's primes, including the 50/1.8. I know it's not a RF experience but I don't mind using the F100. It's a great camera. My only concern would be focusing in low light. RF are supreme for that. Manual focusing an SLR is a bit tricky in certain situations. Thoughts?