I bought the 12-"lens" set from Pinhole Resourses, and I've been using the .0102"/.259mm pinhole on my 4x5. This one's claimed optimal focal length is supposed to be 48mm. I am using it with a recessed lensboard to a length of about 50mm. That's the closest I can get even w/ a bag bellows.
The results are fantastic. I love the focal length. Unfortunately, its fall-off is quite noticable. No vignetting, but the fall-off is about 1.5-2 stops from center to edge. So I think I have to try the next one of the bunch, the one whose optimal focal length is reported to be 73mm. That seems like quite a jump, though. Before I try this at a shorter bellows length than 73mm, has anybody done this? Will I have problems just shooting this at, say, my 50mm (w/ bellows compensation)? Does their "optimal" mean "longest"? That's what the 48mm seems to mean, that if you go even to 50mm, you'll have fall-off. Anybody w/ experience of this? If this works, should I consider ordering a 50-55mm pinhole to fit my 4x5? I really like the weird, extreme result from the short one -- it's just that the light fall-off makes cyanotypes very difficult to print. I'm anticipating that albumen won't work much better. Thoughts? Mike Healy
