I am setting up a shot I have tried before…unsuccessfully. Here are the specs. I am foggy on the bellow extension factor and reciprocity failure. The set up is for a head shot in the outdoors. It is about a 2X enlargement.

20 x 24 Ilford FP4 film (125 ASA)

About 90 inch bellows

About 50 inch subject to lens distance

24 inch Goerz Artar Red Dot lens apochromat (American Optical) (no shutter) at f11

Gossen Luna Pro meter reads 17 which indicates a speed of 1/1000 at f11

What exposure should I use?

Thanks,

Francis