I used a micrometer…
I solved for 1.9 X the square route of focal length (2.1002 in.) times the wavelength of light (550 nm), just like wikipedia told me to. I was convinced, if I was precise, I could make a so sweet pinhole picture. In the end, I probably could have gotten similar results with a cell phone. Oh well, maybe down the road I’ll come up with a good use for my new 46/f.190 but I think it was never meant to be. The light-leaks on wavy film create the charm of a pinhole pictures.
Sometimes the best parts are the imperfections.
Now I have to go clean my sensor.