Pinhole Calculator
Calculate the optimal pinhole diameter for your camera's focal length. Based on the Rayleigh criterion for maximum sharpness.
Calculate pinhole size
Enter your camera's focal length (distance from pinhole to film)
Optimal pinhole diameter
0.32mm
(315 microns)
Effective aperture
f/159
+6.6 stops from f/16
Exposure adjustment
Multiplier vs f/16
98×
Stops compensation
+6.6 stops
If your meter reads 1/125s at f/16, your pinhole exposure would be approximately 0.8s (before reciprocity compensation).
Remember: Pinhole exposures are typically long enough to require reciprocity compensation. Use the Reciprocity Calculator for your specific film stock.
Quick reference table
Optimal pinhole sizes for common focal lengths
| Focal Length | Diameter | f-stop |
|---|---|---|
| 25mm | 0.22mm | f/114 |
| 50mm | 0.31mm | f/161 |
| 75mm | 0.38mm | f/197 |
| 100mm | 0.44mm | f/227 |
| 150mm | 0.54mm | f/278 |
| 200mm | 0.62mm | f/321 |
| 300mm | 0.76mm | f/393 |
Understanding pinhole photography
A pinhole camera uses a tiny aperture instead of a lens. Light passes through the hole and projects an inverted image onto the film or sensor. The result is an image with infinite depth of field but lower overall sharpness than a lens.
The Rayleigh formula
The optimal pinhole diameter balances two factors: a smaller hole gives sharper results (less light scattering), but too small causes diffraction blur. Lord Rayleigh's formula finds the sweet spot:
d = 1.9 × √(f × λ)
Where d = diameter, f = focal length, λ = wavelength of light (~550nm for green)
Making your pinhole
- Use thin brass shim stock or aluminium from a drinks can
- Sand the material thin and flat
- Make the hole with a fine needle, rotating gently
- Sand the back to remove any burrs
- Measure with a loupe and ruler, or use a scanner
Log your pinhole experiments with Silverlog
Coming soon