I did a little research on this subject when looking into enlarging lenses and came to the same conclusion as many others who have already posted. A supposed Apochromatic (APO) lens is designed to focus all visible wavelengths of light (red, green + blue) to a common point. In his book "Edge of Darkness", Barry Thornton says that even the most expensive modern APO enlarging lenses are only corrected for two, and in fact the only true APO lens is the long discontinued Apo El- Nikkor which you will pay a princely sum for if you can find one. Not without suprise he wasn't able to tell one bit of difference between a modern Apo lens and a high quality non Apo lens. At 1 stop down from maximum aperture the 80mm APO Rodagon was about equal to other high quality non Apo lenses but at other stops it was suprisingly slightly worse. Interestingly enough there seems to be quite a bit of variation of quality among identical makes of lenses even with the most high dollar manufacturers so its best to try the lens out for yourself if possible before you purchase. My opinion would be to save the money for a high quality camera lens.