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by Ed Buffaloe
I have encountered elaborate procedures for making pinholes, most notably from Larry Bullis at http://www.pinhole.com/resources/articles/poke.php (from The Pinhole Journal, Vol. 3. No. 2). Kurt Mottweiler taught me a simple technique that has worked well for years. (This is by no means a criticism of Bullis’ method--just another, possibly simpler, probably less precise, technique.) It takes less than 20 minutes to make a good pinhole.
Use brass shim stock, which can be purchased at a local hobby shop, auto parts store, or hardware store. I prefer to work with .005 inch thick shim stock. Snip a piece of brass about one inch
square, place it on a block of wood, and make a dimple in it with a blunt instrument. My preferred blunt instrument is a Bic pen. Tap it just hard enough to make the smallest possible dimple--a millimeter or
less.
Then, with the needle of your choice, poke a hole through the dimple from the concave side, so the rough turned-up edges of the brass stick up above the top of the dimple. Make sure the needle goes straight
in--if it goes in at an angle, the hole won’t be round. For a very small pinhole, don’t push the needle all the way through. Use a hone to remove the sharp edges of brass. I like to start with a
soft stone, such as the stick-like hones sometimes used by watchmakers. Turn the piece of brass and stroke the hone across the dimple from every direction. Then switch to a hard stone. A hard Arkansas stone
works well. The manmade Case Moonstone is also an excellent choice.
As you work the metal down, occasionally examine the hole with a loupe. At some point it may become necessary to use a round wooden toothpick to remove jagged edges around the
pinhole, or poke them up so they can be honed. Do this carefully so as not to enlarge the hole any further. Compressed air is handy for blowing debris out of the pinhole. The
purpose of the honing is to smooth the jagged edges, but also to wear the metal down so it is as thin as possible right at the edge of the pinhole. The hole must be perfectly smooth and round to make a good image.
You can use a permanent marker to blacken the brass on one or both sides. Blacken It or Hobby Black are also effective. If you intend to use the pinhole in a view
camera, cut a half-inch square hole in a piece of matte board and tape the pinhole in the center of it with black photographer’s tape. Cover the entire piece of matte board with the
black tape (at least on the side that faces the interior of the camera). Cut the board big enough to cover the hole in your lens board or homemade camera, and tape it on with more black tape.
Automotive feeler gauges can be used to determine the size of the pinhole, or, if you possess something as exotic as a micrometer, you can “mic” the needle and simply add a few
thousandths of an inch or millimeter (since the hole will inevitably come out a bit bigger than the instrument used to make it). I have a reticle in a 6X magnifier, designed for
determining the size of type (it is labeled Type Size Finder)--one side is marked in picas, and the other in increments of .005 inch. You can buy a 10X Comparator with reticle from
various sources that should serve very well for determining for this purpose--do a Google
search on 10X Comparator. Write the size of the hole on the taped-up matte board.
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