I first started playing with pinhole images with Seamus Ryan, using his 5x4 purpose-built pinhole camera. Once we sorted out the exposure for antique Kodak Tri-X sheet film, the results were good enough for me to want to do more. The downside of using 5x4 film is the time it takes from exposure to knowing that you screwed up and the difficulty of working in colour.
The obvious next step was to try taking pinhole images with my X-T1 (this works with most DSLR’s and better still with mirrorless because you can see when you have got the exposure correct)
The tried and tested solution is to drill a large hole in the centre of a spare body cap and then to stick a piece of foil with the pinhole in behind the hole. Sounds simple and it is, but for one thing. Making a suitably sized pinhole is pretty much impossible using normal methods.
The first attempt used a copper foil pinhole that came along with a “build your own pinhole camera” book. The pinhole was designed for a 5x4 format and turned out to be too large to use with an ASPC sensor. There is a calculation(http://pinhole.stanford.edu/pinholemath.htm) for deciding the optimum pinhole size for a particular focal length (distance from the pinhole to the sensor). I appears that the optimum for an ASPC sensor is around 0.2mm, whilst for 5x4 it is nearer 0.4mm. The results of my first attempt below were interesting but a little disappointing
0.4mm Pinhole for DIY Camera Kit
Tin Foil DIY Pinhole
A little sharper but still disappointing compared to 5x4
Spurred on by some measure of initial success, I decided to order some copper foil and attempt to make myself a 0.2mm pinhole, which is around the optimum for an ASPC sensor
Have you tried making a 0.2mm perfectly round hole in a piece of copper foil? I have and unless I’m missing something significant, it is pretty much impossible. Add to this that the thickness of the foil around the hole is critical, as there is a tendency for inaccuracies to generate fringing caused by interference patterns. It is amazing how far from circular a hole made in copper foil with a circular needle is when viewed through a magnifier!
The results from these homemade pinholes were still much less satisfactory than the results we achieved with the 5x4. This is because as the film (or sensor) size decreases, the optimum size of pinhole also decreases, to the point where it is not possible to make one with normal domestic equipment. The solution? There is an eBay seller in the USA who sells pinholes that are laser cut to scientific instrument standards. Including carriage, a body cap with a laser cut pinhole costs around £15. I ordered one online and it was with me in a week. What a difference. Gone is the fringing. The images are much sharper and have an impressionistic quality to them - wonderful
Home made pinhole
Best attempt copper foil, needles, sand paper and several hours frustration
02.mm laser cut pinhole
Much sharper with less interferance - probably the best solution
Having overcome the technological challenges, the next challenge is to understand which subjects lend themselves best to the type of image that a pinhole delivers. Images that rely on sharpness don’t work at all.