I have both the CF and CB 80 mm's---the CB in kit form on my 501 C/M---I've used both and my eye see's no difference and I have a pretty critical eye (No! Not a pretty eye and an ugly eye!)---- I personally prefer the CB just because I've gotten so used to it--no complaints and it's not an inferior lens in any way !! I think the buyer would be well pleased either way but if you'll always be "wondering" about the CF being better then save yourself that headache and get the CF version---I'll keep my CB and the CF is mounted on a shelved camera !!