I posted this on another thread, but it seems appropriate here also...
I needed to know the mag factor so I could decide if I wanted to switch to an APO lens. My Rodagon 80mm is best around 6X. My 16x20's come to around that. My 20x24's are around 9X. The APO Rodagon is best around 10X.
Since the detail and contrast that I'm getting now printing on Ilfochrome is so fantastic, I have decided that the APO would be a waste of money for my current format. Besides, Ciba doesn't need any more contrast!
Thanks to all for responding.