How to Use the Pinhole Optics Calculator
Get f-number, optimal pinhole size, and resolution trade-offs without a spreadsheet.
Open the Pinhole Optics Calculator
What this tool answers
Given focal length and pinhole diameter (or a target resolution), what are the effective f-stop, diffraction-limited spot size, and a sensible optimal hole size?
When to use it (Guyana)
Use when designing a solargraphy box, room-size camera obscura demo, or classroom pinhole for STEM. Tropical workshops often use cardboard and aluminum foil, this calculator keeps diameter and depth consistent before you punch foil.
Step-by-step
- Open Pinhole Optics Calculator.
- Enter focal length (pinhole-to-plane distance).
- Enter pinhole diameter, or use the suggested optimal size.
- Read f-number, spot size, and any resolution notes.
- Iterate until softness vs brightness trade-off matches your goal (solargraphy prefers tiny, sharpish holes; demos may prefer brighter, larger holes).
How to read the results
- f/#: brightness / depth-of-field analogue for pinholes.
- Optimal diameter: classic sweet spot for that focal length.
- Spot size: larger than optimal → geometric blur; much smaller → diffraction blur.
Common mistakes
- Mixing millimetres and inches.
- Optimizing only for theoretical sharpness and forgetting exposure time.
- Using foil holes that are oval or torn, geometry assumes a round aperture.
Next
- Topic: Pinhole Optics
- Build preview: Solar Pinhole Camera
- Field craft: Solargraphy