Quote Originally Posted by Drew Wiley View Post
Fresnels might help with wide angle lenses in dim light. But they can be counterproductive with longer lenses like a 240 for 4x5. I don't like them at all.
Fresnels help with telephotos if you use a monocular viewing hood. The lens on my hood is very close to the GG and with a 600mm is fairly even, with a darkcloth not so much. There are different focal length fresnels too, one company listed 2, one for wide, one for tele, not much hard info though.