RB67 pinhole camera?

[paul ron]

john i was trying to think how i could just use the film back. there are a few things i have to work out first. its a graphloc so mounting my mod should be fairly easy.

whats the minimum distance f-l to cover a 645 or 67?

 

[paul ron]

I'm not sure how to interpret a recent pinhole experiment with my Mamiya RB67. I used a pinhole about 0.3mm diameter about 5 inches in front of the film and got the predictable result. Putting the same pinhole over the front of my 127mm lens gave a very similar result. It seems that when the relative aperture is maybe f300 or smaller the presence or absence of a glass lens makes no difference. It's all diffraction limited anyway.

Could it be that all cameras become pinhole cameras merely by putting a lenscap with a suitable hole over the lens?

just put a pinhole lens over a glass lens? im using a front body cap with a hole.

 

[Maris]

just put a pinhole lens over a glass lens? im using a front body cap with a hole.

My basic idea was to overcome the pinhole camera's lack of precise framing. First compose the picture with a regular lens and then put a pinhole lenscap on and, voila, a pinhole image! This may even work with non-interchangeable lens cameras that one might not want to disassemble for the occasional pinhole picture. Caveat: pinhole lenscaps cause vignetting with some lenses. Check to be sure.

 

[paul ron]

i dont see any advantage in doing this with my beast but the idea is intreging. ill try it later. maybe on a 35mm camera just for the reduction in size.

 

[John Koehrer]

RE:fl on a film back, you can pretty much pick a fl you want to try.
Is it pinhole doctor that's got a calculator?
Of course there's always zone plates. Never seen one but the term pops up now & again.