Originally Posted by Contrastique
... It's nice to have f4 for focusing although the lenses I've used so far are all f5,6. Thanks for the comments!
Even so, you need to stop it down to about F8 for optimum image quality with 6x7, so the F4 aperture is rather trivial IMHO. I have the 80/4 APO-Rodagon-N. It's a nice lens.