I have an extra linhoff style lens board and I thought I'd see if it wouldn't be possible to manufacture a pinhole that could be taped inside the hole. Does any one have any suggestions about how to manufacture a pinhole that would provide a known f/stop on a 4x5 field camera?
The quality won't be great, but for experimentation, try cutting an aluminum beer can to the shape you need. The use a #10 sewing needle to punch a hole in the center of the aluminum. Place the aluminum on a pad (a foam mouse pad works well), hold the needle with pliers so you don't punch your finger. After punching the hole, sand the opposite from which you punched with 400 grit paper. the #10 hole will be about f256 +/-.
If you want to do higher quality work, you'll need to find brass shim stock. There are a few websites on pinhole photography. Here are three that I have bookmarked. Hope they are still active. http://unblinkingeye.com/Articles/Pinhole/pinhole.html
http://members.home.net/penate/pinsize.htm
http://www.pinhole.com/resources/articles/poke.php
Good luck. Pinhole is fun, a little unpredictable, e.g., difficult/impossible to aim camera from ground glass, but everything is in focus.
J
See my article How to Make a Pinhole. I indicate two different methods I use to determine the diameter of the hole--using a micrometer on the needle and using a reticle designed for measuring type. However, precision is not essential. Decide what "focal length" you would like and calculate a pinhole diameter that will give you approximately f/256 or f/360, then see how close you can get to that pinhole diameter. You can always adjust your exposure times to compensate for inaccuracies in measurement.
How about seeing MY ARTICLE, too. http://www.luminous-landscape.com/pinhole.htm THANKS You will see a 4x5 custom pinhole camera and other easy to make, cheap cameras and all the images with the article save one were LARGE FORMAT as is my Pinhole Resources gallery show. My article is designed to aid common-sense photographers-not the artsy crowd. I am always glad to answer questions and help with sourcing materials. Since
the above links may include this, but you can get a fairly accurate measure or the pinhole diameter using your enlarger. Just pop it in a film carrier, raise the head, focus the hole, measure and reduce by the enlargement factor.
I used a sewing needle to poke the hole in some .003" brass, and a 25 gauge syringe needle (.5mm) to size the hole. It's an almost perfect 150mm, F/300 lens for 4x5.
I recommend highly the set of pre-drilled pinholes you can buy from Pinhole Resource. They come in 10 (12?) different diameters with a chart that tells what they are, what aperture that equals, and what exposure factor to use. I have taped these small pieces of aluminum over the lens board hole and used them on my Arca 6x9 with great results. You can even see the image (sort of) on the ground glass. You do have to measure out the correct focal length to extend the lens board. The chart is right on. The holes are perfectly machine drilled so the images are sharp, maybe sharper than a typical pinhole vision.
The only problem is, it makes it so easy it takes some of the fun out of experimenting.
David Stein wrote: "My article is designed to aid common-sense photographers-not the artsy crowd."
When are we going to get over the annoying anti-"art" rhetoric on this forum? David, do you think "the artsy crowd" has no use for "common- sense" advice? Do the rest of you with artphobia think artists cannot possibly be serious about their process or their equipment?
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