
Originally Posted by
Greg
Years ago experimented with shooting through 25, 58, and 47B filters in order to get sharper pinhole images. Unfortunately my pinholes at the time were mediocre, so my results were less than valid. Also didn't like the non panchromatic image results.
On this end I start with the pinhole's diameter as recommended in Eric Renner's book PINHOLE PHOTOGRAPHY. Made several pinholes at his recommended diameter in several different materials (Brass shim, Stainless Steel shim, DASANI sparking water aluminum can, aluminum foil, and a few more). Settled on Brass and Stainless Steel .002 gage shim stock. Both of the pinholes are blackened on the inside "walls" of the pinholes and then inspected under a microscope. If the pinhole isn't nearly perfectly round (most aren't), I re-blacken it and inspect again. Sometimes takes several tries. Compared the SS and the Brass pinholes and settled on using Brass shim stock because it was easier to blacken the surfaces. Then I make successively smaller pinholes to shoot test exposures with. Even though the pinholes will be used on an 8x10 (and another 11x14 to follow) WA camera, I shoot test exposures on 4x5 film at the same focal length of my 8x10 pinhole camera. Easier to batch process the 4x5s and way less expensive. I then compare the sharpness of the negatives and one almost always stands out. This is the one I use on my camera. When I determine which size hole to use, I make several more pinholes and then gently hammer the pinhole with a ball pean hammer to flatten the metal a bit more making the "wall" of the pinhole minimal thickness. I have to gently re-drill the pinhole after flattening it. Any burs around the pinholes are removed. Then blacken them. Having made several pinholes in this manner, I finally inspect them under my vintage Nikon Ske microscope with Axial (Brightfield) Illumination (hope I've used the correct terminology). They will all look different under the microscope so choose my favorite (and hopefully best). The pinhole images I get with my pinholes are noticeably sharper than any of the commercial "laser cut" pinholes I've purchased.
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