150mm lens, for 4x5 negatives. The largest prints I make are 11x14, so we're talking pretty low magnification here. I'm looking at the Schneider 150mm Componon S. Is there any reason to even bother looking at the APO Componon?? For obvious reasons ($$$$$$$$) I'd rather not.
I'm quite sure at these enlargement sizes I'd see no difference whatsoever in sharpness, contrast or uniformity of illumination (prove me wrong). But one thing I've always liked about APO lenses in smaller formats is they usually reach optimum performance one stop wider than the equivalent non-APO versions (I use an 50mm APO Rodagon for enlarging 35mm). So I don't know.
Do you have a grain magnifier. When you open your existing lens up one stop more than usual when making an 11x14 are the corners still sharp?