Pinhole Construction

I was wondering if anyone has tips on easy construction of a pinhole.

I can get very thin drill bits (I have a friend who does model

airplanes and has wire bits) but what materials are best for the

construction of thre aperature?

 

Thanks.

Jason, I used to always use .005" or .010" Brass shim stock. Better hardware

stores and hobby stores will sell it. I used to double check the pinholes with a

20x magnifier to make sure they were clear and round.

I used disposable pie plate aluminum a couple times, but found it didn't cut as

cleanly as the brass.

I've allways just use think baking sheet cut into square inch pinhole plates. I'd get the smallest sewing needle I could find and loaded it into a mechanical pencil to give myself a good grip that I could easily control on it. Gently poke the plate from one side and then turn it over, sand down the burr and repoke it from the other side to clear any debris that is in the hole. Then I'd put teh plate into a plastic mount for a 35mm slide and run it though my film scanner at the highest resolution. With the scanned image I could just select the white area of the image to measure the diameter in photoshop.<div></div>

Different focal lengths will require different sizes of pinhole. There are some nice "pinhole sets" available with laser drilled holes of different sizes. Calumet always had these and I see them on Ebay occasionaly. For a quicky at about 3 inches from the film just tape a piece of foil in a 1/2 inch aperture and puncture with an insulin needle.

One trick I have seen used is to first make a little dent to the brass plate and sand it down from the raised side, in effect to make the brass plate thinner in one place. Then poke the hole into the middle of the thinner plate. This gives two benefits: it is easier to poke a hole into a thinner brass plate, and the thinner wall makes for a sharper pinhole.

The material for making your pinhole is almost as varied as the materials which may be used to construct the camera body. Successful pinholes can be made using heavy duty aluminum foil (cheap and easy to puncture but poor longevity), brass shim stock (available from most hobby stores), silver foil (rolled to desired thickness by a jeweler), pie and baking tins, old soda or beer cans (my favorite - leave the painted logo intact for "decoration").

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Even the smallest drill bit can be too large for a short focal length pinhole camera. You can get an idea of the diameter you will need for your camera with the <a href="http://www.mrpinhole.com/calcpinh.php">Pinhole Camera Design Calculator</a>. The previously mentioned techniques of dimpling and sanding seem to work well for making clean round holes in thin materials. You can find more tips on pinhole construction at the <a href="http://www.pinholevisions.org/resources/">Pinhole Visions Resource</a> pages.

See my article <a href=http://unblinkingeye.com/Articles/Pinhole/pinhole.html>How to Make a Pinhole</a> for instructions on using brass shim stock. I have a friend who successfully uses aluminum from soda and beer cans.

I've posted several responses here over the last few months on pinhole making. In short:

 

1).002" sheet brass.

2) Sewing needle, eye end inserted into small balsa block as a hand-drill tool.

3) Gentle pressure, rotate the square of brass, not the needle.

4) When the tip of the needle begins to poke through, gently polish the dimple-side of the hole using 600 grit emory paper, using circular motion. Don't push the needle all the way through up to the full thickness of the shaft. Only use part of the tappered tip.

5) Examine pinhole using loupe. It needs to be extremely clean, circular and burr-free.

6) For the sharpest images, go to about 10% smaller then the Rayleigh criteria would suggest.

7) Smoke the inside of the pinhole with a wooden kitchen match or candle. Prevents "lens flare" from sunlight glinting off the inside edge.

8) Measure the pinhole diameter on your enlarger. Use a calibrated length projected from clear sheet plastic, then insert pinhole and measure onto baseboard, calculating the diameter using your new-found calibration factor.

9) Don't use drill bits. They'll chew up the metal, especially thin sheet brass. You can't get flat, even circular holes that way.

10) You want a nearly 2-dimensional (flat) pinhole, NOT A TUNNEL! Thus, use as thin a sheet metal as you can find. .002" is practically as thin as you should go and still be able to handle it without destroying it.