Quote Originally Posted by MattKing View Post
A single colour filter (e.g. a yellow Y2) can certainly improve the black and white performance of a lens that otherwise suffers from chromatic aberration.
Indeed, I usually use a yellow or orange filter with my Busch Vademecum set for this reason. Of course when the lens was made, plates were blue sensitive or UV sensitive, so chromatic abberation wouldn't show up on the plate, but the set came with two corrector filters for focusing to compensate for UV focus shift. The corrector filters would be removed for the shot.

That said, a MC filter won't reduce flare on an uncoated lens.