When Canon moved from the old FD lens system to the new EOS models changed many things, most of them very good. A bad news, however, was that the extraction of the new lens system is shorter. This mean that the old lenses cannot focus to infinity when rigged over the new bodies, saddening and upsetting the pockets of generation of FD owners.
An apparent solution to the problem is offered by adapters that allow the infinity focus of FD lenses by lifting their focal plane with a negative lens. I grabbed one of those, piggybacked a 300D to the telescope with a bunch of lenses to test and these are the results...
FD 24 mm f2.8 used at f4. Lyra-Cygnus region. The North America area is faintly visible on the top left corner.
The uper left corner seen in real size. Stars appear horrible: coma, astigmatism, chromatic aberration. Name an aberration and these stars have got it!
In the very centre of the frame the situation is marginally better, but at the stretching levels usually used by us, some serious chromatic aberration, not present on the excellent lens itself, is sticking out its ugly face.
Copyright © 2004 by Gimmi Ratto. (December 22, 2004)