<p>I found time to play with RetroPAN 320 in 4x5" over the weekend - not in a camera, but using a sensitometer to expose it. I found that Foma's recommended time of 7-8 minutes in HC-110 dilution B (1:31) at 20 deg C seemed spot on for a diffusion enlarger. Since I use a condenser enlarger, I ran a set of tests as described by Ralph Lambrecht in "Way Beyond Monochrome" using dilution E (1:47) (except I mixed it 1:49 because that's so quick and easy to do using a 20ml syringe and a 1l mug).<br>
The results show the required average gradient is reached at 4, 6, 8, 12, and 18 minutes in HC-110 dilution E at 20 deg C for N-2, N-1, N, N+1, and N+2, with an extra 1/3 stop exposure at N-1, and 2/3 stop at N-2.</p>
