If you are using a 4x5 negative with a 105mm lens I expect you will have trouble at the edges.
150 mm will give you better coverage.
Originally Posted by Chris Lange
I have the negative centered in a 4x5" AN glass carrier, using a EL-Nikkor 105mm/5.6, and a peak grain focuser. I'll try to track down a sheet of metal tomorrow. Thanks for the tips!