Hello. Many years ago I removed the UVa filter from my good old black first version Summicron 90mm...shooting with Tri-X, wide open aperture and even with it's hood extended when cross light "caught" the filter glass there was a tendency to flare.Removal of the filter helped.I intend to keep the lens. <p> Do any users of later Summicron 90 designs,even the current Apo,experience any potential flare is increased with filter attached? Regards.