Free pinhole optics calculator: optimal hole diameter, f-number, field of view, and blur for any can or box camera build.
Frequently asked questions
How do I calculate the best pinhole size?
Classic guidance balances diffraction and geometric blur: diameter scales with the square root of focal length. This calculator applies practical maker formulas and shows how blur changes if you drill slightly off-optimal.
Does pinhole size matter for solargraphs?
Yes. Too large a hole softens the trail; too small increases exposure time and diffraction. Match hole size to your can depth and paper distance before committing to a multi-week exposure.
What focal length should I use?
Focal length is roughly the distance from the pinhole to the paper. Deeper cans mean longer focal lengths, narrower fields, and different optimal hole sizes, adjust the calculator to your measured depth.