Why make it more complicated than it really is? Do you really crop THAT tightly and must your proofs show the entire frame right out to the edges? Cut out a square of paper 4x5 and one 3.25x4.25 and compare. You'll be surprised how close it actually is. If you need, make the mask for the ground glass and you can then re-position the center for the 4x5 shot with just a touch of rise (if shooting vertically - as is probably likely for portraits) or shift, if shooting horizontally.
Get a 405 back and some FP100c. Shoot portraits. The size difference just isn't that important for proofing purposes.
Last edited by Roger Cole; 07-28-2012 at 12:44 PM. Click to view previous post history.