Currently, I'm using a borrowed Zero Image 2000 (f138), photographing slightly moving people/objects inside, generally getting 5min exposure times with FP4. I'd like to use a curved plane 120 panoramic but without the ?25min times that the usual f250+ would give me.

I would like it to be somewhere around f140 - for an 80mm focal length that would mean a 0.6mm pinhole. How might that affect things? Would I start to see unwanted artefacts?