I know one way to make a pinhole is to use a needle and the sizes are given in some of the charts. But the sizes of needles are different for different uses. A #12 isn't the same size in beading as it is in other things, for example. Which type of use are the sizes given for pinholes from? Are they just handsewing needle sizes?
It's not a stupid question. The needle industry has long failed to support pinhole photography in this respect. Maybe it would help if we atarted to use the name needlehole photography. Even Eric Renner, in the first edition of his otherwise excellant Pinhole Photography: Rediscovering a Historic Technique, doesn't specify just what needles are the basis of his chart. A carefully used micrometer can calibrate any pins or needles at hand. Fortunately, there are many other ways to measure pinholes. One is to scan the pinhole at maximum optical resolution, count the pixels across the pinhole, and calculate the diameter. The image of a pinhole can be projected and measured in an enlarger or slide projector, and the diameter calculated. I use an old Spiratone optical micrometer comparator, but similar devices seem to be scarce and expensive now. A standard microscope calibrated with an ocular reticle would be easier to use. A micrometer XY measuring stage on a microscope might suffice. Someone with sensitive and accurate photometry equipment might compare the light transmitted by a reference pinhole with one of unknown diameter.
I do a quick-and-dirty version of the micrometer comparator, just a high-powered loupe, which I use to view the pinhole as it's placed adjacent to a millimeter scale, and backlit enough to clearly see the hole, while still having enough light on the front of the scale to get a reading. My process is to approximate the diameter as a fraction of a millimeter. I can get pretty close to 1/3 or 1/4 mm resolution, which is plenty of accuracy for the overall process.
I think it's essential to view one's pinhole under high magnification to get an idea of the overall quality of the hole, as I'm under the opinion that the quality of the hole is at least as important as getting the diameter to within a gnat's derrier of optimal. I've frequently had to trash a pinhole and start over, just because it was out of round, or had a burr on the edge that wouldn't go away without completely augering out the hole to way-too-large.
I've also been rethinking this idea of "optimal pinhole diameter", as it seems like an oxymoron, like talking about the "optimal oxen-pulled plow", whereas an air-conditioned John Deere may come closer to being "optimal" for the purposes of agriculture. I suppose I'm having guilty pangs about having overly-intellectualized the art of pinhole. I think a good image speaks for itself, regardless of how it was made.
~Joe
We made some pinhole measuring rulers with a imagesetter. I have a series of dots; diameters from .10mm to 1.0mm in .05mm steps. With a low cost magnifier (x15) it only takes a few seconds to measure accuratly the size of the pinhole. Forget about the scanner, slide projector, it's ay too much bother once you've tested this out.
I can send you, or some other volunteer, the files if you want to make a bunch in the US. And you can dispatch them around you.
Maybe one day I'll start an eBay buisiness selling them and zone plate...
Have a look here.
Spot on. I can't believe people spend good money on laser holes & what-not.Originally Posted by 1351
But we digress - POB offers a good idea here. Another alternative is to go medical.
I discovered sometime ago, needles that were cheap, readily available, accurately made & in sizes ideal for us pinholers. They are acupuncture needles.
I found some on the american ebay site sized 0.20mm, 0.22mm & 0.25mm.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310094886055
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310084415682
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310094886235
They may help you to accurately size a hole.
there's an old thread in which Earl lays out this great chart:
Sewing Tapestry, Chenille Diameter Diameter
Needle and Yarn Darner in inches in millimeters
Size # Size #
- 13 .092" � 2.34 mm
- 14 .082" 2.03 mm
- 16 .064" 1.63 mm
- 18 .050" 1.27 mm
1 - .046" 1.17 mm
2 20 .043" 1.09 mm
3 - .040" 1.02 mm
4 22 .037" 0.94 mm
5 - .034" 0.86 mm
6 24 .030" 0.76 mm
7 - .027" 0.69 mm
8 26 .024" 0.61 mm
9 - .021" 0.53 mm
10 - .018" 0.46 mm
11 - .016" 0.42 mm
12 - .014" 0.35 mm
entire thread here:
http://f295.f295.org/uploads/Blah.pl?m-1179068411/s-2/highlight-needle/#num2
tom - you beat me to the punch. The problem is that it is not often easy to tell which type of needle you have in your hands.
These needles are very very soft, I mean they bend too easily to be any good at punching holes. And if you want to use them to gauge your pinhole, they would probably damage the borders of the hole.
My uncle is an acupuncture practician. I tried a few times but with no success.
Some people around here have tested the rulers I made and that I offered in the print swaps. I'd be curious to have their feedback.
Thanks all for the great replies. If I still had access to a microscope, measuring the hole would take me about 5 seconds. Unfortunately, I can't do that now. I wish....
Tom, that list is much more complete than the one I'd seen elsewhere and is a big help. Hopefully, something in my sewing pile is still in its original package.
Just uploaded the Illustrator file (CS3) for the pinhole measuring ruler. The pdf file doesn't let me have pure blacks and always makes composite black instead of 100% process black.
You can grab it here:
http://puffskydd.free.fr/poby/stenope/pinhole_measuring_ruler.rar
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