I am having a little trouble with this Canon FD 24mm 2.0 that I got to fill the low light needs between 35 and 15mm. After getting the lens and shooting a little bit around I noticed that I get a lot of CAs and not that sharp results. I am wondering if this could be a problem because the lens focuses past infinity when set to infinity. Since the lens has a floating element and sits a little too close to the sensor it might be that it is not performing as it should. Am I on the right track here, or is it something else ?
Depends on how much of a registration error you have.
To put things in perspective - you can use the early FD and Nikon AIS lenses with pseudo-floating elements ON EXTENSION RINGS and still get good results. That's inducing a registration error of 7, 13 or 20mm - or whatever thickness the extension has.
