Thank's both for your replies. That is not a factor I was aware of at all, very interesting and dissapointing. My Megrez 90 doesn't currently show any violet fringing but it is only a doublet and I wouldn't want to tempt fate, spend $3,000 and have it wasted. I do wonder if a violet reduction filter would help? but obviously that would cut sensitivity.
I am specifically interested in single-shot-colour for this scenario so won't be considering a mono chip, rather looking at alternative OSC chips.
Thanks
