Schneider 40 & 45, 40 Focotar all give awful corners with condenser enlargers, however they work fine with diffusion machines. i have 7 enlargers from 35 to 4x5 that print all formats and tried them every which way, single glass, double glass, no glass carriers, you name it. Do not buy them for a condenser machine.

I will have to disagree reguarding APO. There is a "clarity' difference that is unmistakable, sharpness not so much, but it is there. I have tried all versions of Leica Focotars, Rodenstock N APO, and older Nikors. The German are the best.