A question - I recently bought a Zeiss 35mm Biogon C 2.8 and coded it manually in my M9, as recommended here and elsewhere, as a pre ASPH Summicron. I then bought Tim Isaac's Decoder 2.0 kit and coded the lens as a 35mm Summarit, thinking that the Summarit was closer to the Zeiss in f stop / speed. I only took 50 or so pics with the manual / in camera Cron coding, and have been shooting since (400 or so shots) with the Summarit coding on the lens. Both settings seem to yield suberb results, and I can't really see or remember a difference in IQ between the two settings.
I have seen that others continue to code the Zeiss as a pre ASPH Cron (perhaps even with the decoder kit or having the lens coded professionally). Does anyone have experience with the IQ of each setting and whether the Cron is a better choice for coding the Zeiss? Is there a definitive answer here or is it really more a matter of personal preference?