blackwrap pinhole lens AF100 screenshot

In a photography class I taught for graduate students at the University of Illinois for several years, we set about improving the classic pinhole camera built from a cylindrical Quaker Oats box. We read everything there was to be found on pinholes and concluded that the best results came from improving the precision of the pinhole itself. Simply punching a hole in a piece of foil produces a pretty irregularly shaped hole, typically too small, that diffracts light a lot and with irregularities that cause, for lack of a better word, irregular "bokeh" effects in the image.

The recipe for the ultimate pinhole was, more or less:

1) Use a piece of brass shim stock of about 0.01" thickness for the pinhole.
2) Punch the hole with a #10 sewing needle, which is about the right diameter. This can be rather tough going and you'll want to wear heavy leather gloves for the operation, as well as hold the needle in a pair of pliers. (Nowadays, I own a set of miniature carbide drill bits, so I might find out what that needle diameter corresponds to and use one of them instead. Probably around #65 or so, but don't quote me.)
3) MOST critical -- polish the edges of the hole until all burrs are removed and the surface of the brass is perfectly flat and highly polished. Start with 400 grit sandpaper and finish up with "crocus cloth" (an abrasive cloth used in precision machine work) to make it shiny. Inspect the hole and make sure it's perfectly round and has no burrs intruding from around the edges. Repeat polishing until it's perfect.
4) Apply LIGHT coats of flat black spray paint on both sides of the brass sheet to minimize reflections. Use the needle to clean out the hole again if the paint fills it. You can also paint the inside of the box you're using for the camera while you're at it.

Mount the brass pinhole over a larger hole (dimensions not critical) cut in one end of the Quaker's box. Seal the edges with black electrical tape or duct tape.

With these steps we found we got much higher resolution from our pinhole images (which were on 35mm film or even photographic printing paper taped inside the back of the box). The same general idea (especially using a slightly larger-than-normal needle and polishing the pinhole thoroughly) would probably work with the AF100 or any other camera as well.

Let us know how your images turn out!

- Greg
 
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Thanks Greg I'll try that out!! I read also a larger sensor like 35mm or medium format the bigger you go the sharper your image will be. Is it possible to get the smaller sensor AF100 to be real sharp?
 
Joe748 said:
Thanks Greg I'll try that out!! I read also a larger sensor like 35mm or medium format the bigger you go the sharper your image will be. Is it possible to get the smaller sensor AF100 to be real sharp?
Click to expand...

Right -- the larger the film or sensor, the better, because you can never resolve a point of light smaller than the diameter of the pinhole itself, so you want to maximize the sensor-to-pinhole size ratio to get the maximum amount of information in the picture. But reducing the absolute pinhole diameter past a certain point makes it diffract light more, so you lose sharpness again, and the needed exposure times can get uselessly long as well. The "#10 needle" guideline was based on trying to optimize the sharpness, and is bigger than most classic pinhole formulas. But it may not be the last word. Using thicker, dimensionally stable brass stock and polishing with crocus cloth were the two things we found made the biggest actual difference.

Still, this is in no way about making the sharpest possible pictures, obviously, so I say go and have fun with it and let us all know what it looks like, whether on your AF100 or a view camera!

(How about two side-by-side pinholes with a red filter over one and a blue filter over the other to make "stereo" images? :-)

- Greg
 
> the red car picture in my avatar - its a pinhole, shot on kodak asa 200 while in havana '02

Well that's some interesting back story to an avatar that's been all over the place here...
 
j said:
> the red car picture in my avatar - its a pinhole, shot on kodak asa 200 while in havana '02

Well that's some interesting back story to an avatar that's been all over the place here...
Click to expand...

thanks, I'll tell you the full story over a pint of guiness one day
 
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