Another Pinhole Project With Questions

[SoulfulRecover]

I want to make a pinhole camera using an instant film back from a mamiya rz67. Basically glue a bellows onto the film back, have a plastic piece at the opposite end with a super small hole. However I am sure there is more technical information I will need to learn such as how large of a hole and how do I measure the distance from the film plane to the "lens" for the bellows length? I am sure that is directly related to the size of the hole. I think it would be fun to have a peal apart instant film pinhole camera

 

[limr]

Do you know about this site? http://www.mrpinhole.com/

Pinhole Polaroids are fun. I've got a Color Pack that I intend to turn into a pinhole camera, but just haven't done it yet. Too many other things to get to, like fixing the light leaks in my Land Camera and the shutter in the 645

This is probably something you already know, but the image from the rz67 will be smaller than the size of the print, which is IIRC 3 1/4 x 4 1/4 or something like that.

There are a few folks who use instant backs on medium format (sometimes pinhole shots as well) on another forum I'm on, so you can poke around there, too: Filmwasters - Index

And of course there's also Film Photography Project: Film Photography Project | An Internet Radio Show & On-Line Resource for Film Shooters Worldwide

 

[SoulfulRecover]

thank you so much for the links! If im not mistaken the image size from the mamiyas on the instant film is 7x7. I have an extra back laying around and I figured it would make for a fun project. I did just find a Polaroid 320 on ebay (its in great shape) for 1 dollar. So I may end up using that as a parts supply or hell just shoot with it

 

[limr]

If that 320 works, I would try shooting at least a pack or two through it to see how you like it before using it for parts. Polaroids are surprisingly addictive

 

[SoulfulRecover]

attach

If that 320 works, I would try shooting at least a pack or two through it to see how you like it before using it for parts. Polaroids are surprisingly addictive

I figured Id run a pack or two through it at least.

So currently heres what the specs are looking like for the pinhole:

Focal Length: 10mm
Pinhole Diameter: 0.13mm
f/Stop: f/75
Film Dimension: 10mm
Angle of View: 53.2*
Coverage: 19.007

Mid day exposure should be roughly 1/8th of a second at 100 ISO. Not sure I like that measurement though as I wont be able to overly control that short of a time frame by hand. May end up adjusting the pinhole diameter to slow it down

 

[smithdan]

Thanks for the links limr.
Good luck with your project SR

"Focal" lengths for the image size of the polaroid film pack are more practical at around 10 - 12 cm (100 - 120 mm) This would get exposure times up into the 5 second range with iso 100 and still manageable manually with polaroid (forget, around ISO 600?)

Hawkeye conversion at 0.3 mm and 9.5 cm wants 4 sec with 125 ISO and the K1000 with approx. the same size hole and 45 mm from hole to film plane liked 1 - 2 sec with 400 ISO in the back. Conditions were bright, mixed overcast.

 

[SoulfulRecover]

The film I would be using is Fujis FP100c which is 100ISO so the 5 sec range would work just fine for me. With these short time frames, would recip failure really be a worry of any kind?

 

[smithdan]

The film I would be using is Fujis FP100c which is 100ISO so the 5 sec range would work just fine for me. With these short distances, would recip failure really be a worry of any kind?

Check the specs for this film, but think that with the trial and error involved with pinhole as well as the characteristic image quality, any of the finer points like RF and contrast adjustments in processing are not big factors.

Found so far in practice that the biggies for pinhole are subject choice (minimal detail) and camera stability, as well as the roundness of the hole. All the other factors are back in the pack.

 

[SoulfulRecover]

good to know. I was just thinking about stability. This thing is going to be super light so what I may end up doing is putting a tripod mount on it and some sand bags on the tripod to keep it stable. Ive got more tools than the average person so im sure ill be able to get the hole nice, round and smooth

 

[smithdan]

Give it a shot. Nice effects when it all comes together.

this trick works with long exposures on some of my oldies with no cable release. without touching, hold a black something over the lens (hole), open the shutter, remove the cover, count time, then first the black something then the shutter. Camera is dead still during the exposure.