Pinhole for ULF cameras

[TheFlyingCamera]

I'm interested in a pinhole for my 14x17. Does anyone know of someone who makes them for cameras that large, or have formulas for making such a beast? My camera takes full-size Toyo lensboards, or I can use a Linhof board with a Toyo-Linhof adapter.

 

[FM2N]

So if using a 14x17 inch piece of film the calculations would be-
Pinhole to film distance of 22inches witha pinhole size of 1mm which gives you an f/stop of f/561

 

[removed account4]

hi scott

try photobilly
http://www.pinholeedun.com/Welcome.html
he sells laser holes, i have gotten them from him and they
are wonderful. he gives info on the stop relative to f16 so you can
use a light meter ...

rule of thumb formula for calculating the coverage / image circle of a pinhole.
3 or 3.5 x the relative focal length of the pinhole.

have fun'
john

 

[nsurit]

I'm thinking the answer is to be found on this site: http://skinkpinhole.com/wp/ I use one of their's on my 8X10 pinhole camera. Bill Barber

 

[summicron1]

or you could just punch a pinhole into a piece of foil, or brass stock, with a pin and try it out. Pinhole is vastly forgiving and defies rigor.

 

[DWThomas]

There's Mr. Pinhole on the web that lets you do design calculations without installing anything.

There's also Pinhole Designer which is Windoze based, but a free download. It hasn't been updated in a long time, so it lacks reciprocity data for some newer films, but it's cool for the dimensional designs.

If it were me (a compulsive and cheap tinkerer), I would make my own. A plywood lens board and a dimple-and-sand pinhole plate. Vaguely similar to what I did for my B&J Press 4x5. Hobby shops have fairly high quality plywood used for model aircraft work that is available in small dimensions, both area and thickness, that could be stacked and glued together and sprayed flat black for a lensboard.

Given a pinhole to film distance of 15 inches, Mr. Pinhole says 0.032 inch diameter, f/463 -- for what it's worth. I tend to prefer Pinhole Designer because it's more transparent about what it's doing to generate the numbers.

 

[Jim Jones]

I second Dave's recommendation of Pinhole Designer, but with a user constant of 1.4 instead of the default user constant of 1.9: Lord Rayleigh was more of a scientist than photographer. Pinhole performance defies basic scientific assumptions. The smaller constant yields slightly sharper images. Despite what casual pinhole photographers may claim, pinhole diameter is fairly critical. A 10% deviation from optimum diameter should show noticeable reduction in sharpness.

For many discussions on making and using pinhole cameras, go to http://www.f295.org/main/forum. Another very comprehensive site is Dead Link Removed.