To keep it really simple: for B&W film especially, the exposure compensation that works well in the field is: add 1/3 of a stop for every inch of bellows extension over the focal length of the lens that you are using. EG.: with a 6" lens (150 mm) on the camera and with a bellows extension of 9" (film plane to nodal point of the lens) the exposure compensation would be plus 1 stop. I have used this "rule of thumb" for 49 years and it has served me well.
Originally Posted by Terry Bowyer
(PS: I don't like thin negs. in BW. If in doubt give a little extra exposure: develop according to the scene brightness ratio.
I use a Zone VI, 4x5 with 75, 150 and 240 Nikkor lenses. I also use a 6x7 roll film back which is especially good with the 75 mm Nikkor.
Enjoy, don't over think it, keep it simple. Shoot film, print lots!