As part of building a 4"x5" pinhole film camera for my wife as Christmas gift I had purchased some laser cut apertures of various sizes (0.3mm, 0.4mm and 0.5mm). And I got to thinking: "I wonder what the pictures would look like if I used this on my Sony mirrorless digital camera?". So I set about finding out!
Having access to a 3D printer made this process a lot simpler. All I had to do was work out the what focal length/aperture sizes would be best and I could design a lens barrel. A while ago I bought a whole load of metal minimal Sony E-Mount to M42 adapters (that are only 1mm thick!), so mounting to the camera wouldn't be a problem either. Some Googling taught me that it was best to use the smallest aperture possible (0.3mm in my case) and that there was a formula to work out the ideal focal length for that aperture size which is:
focal length = (pinhole diameter / 0.03679)2
Thus, I worked out the ideal focal length for me was 66.5mm. Taking in to account the flange distance (distance between the sensor and the front of the mount) of the Sony is 18mm and the adapter plate was 1mm thick, I worked out I had to design and print a lens barrel that was 47.5mm long. This is did and then I superglued the aperture in place at the front and the adapter plate on at the back.
My first attempt at a photograph can be seen below:
I am pleasantly surprised with the results. It's not sharp, but I wasn't expecting it to be given how small the sensor is (36mmx34mm) in comparison to most pinholes. Used carefully, I think you could make something out of its dreamy soft focus and I am definitely inspired to see what else this "lens" can do.