How the camera simulator works
| Effect | Model | Simplification |
|---|---|---|
| Brightness | Stops of exposure from f-number, shutter time and ISO compared with the scene’s exposure value (EV 15 sun to EV 3 night), with a soft highlight roll-off | No dynamic range limit in the shadows beyond noise |
| Depth of field | Thin-lens blur circle for each scene layer’s real distance, focal length and f-number; circle of confusion 0.03 mm (full frame) | Five depth layers rather than continuous depth |
| Lens choice | The camera steps back as focal length grows so the person stays the same size | No lens distortion or vignetting |
| Motion blur | Distance the car travels at 30 or 60 km/h while the shutter is open | Straight-line motion only |
| Camera shake | Handheld blur grows once the shutter is slower than 1/focal length | No stabilization option |
| Noise | Random noise scaled with ISO and stronger in darker tones | Same noise model for every camera |
White balance, diffraction, lens aberrations and sensor sizes other than full frame are not simulated.
Calculator formulas
- Depth of field: standard thin-lens hyperfocal and near/far equations, circle of confusion = sensor diagonal ÷ 1500.
- Exposure value: EV = log₂(N² ÷ t), normalized to ISO 100.
- ND filter: new time = time × 2^stops; one stop = 0.3 optical density.
- Stars: 500 and 300 rules and the simplified NPF rule, (35N + 30p) ÷ f.
Editorial standards
- Every setting recommendation is a starting point and says so. The camera's meter and histogram have the final word.
- Numbers on the site are calculated, not estimated: every table can be reproduced with the formulas above.
- Lessons are reviewed and updated when camera conventions change. Each page shows its last update date.
References
- ISO 12232: the international standard for digital camera sensitivity (ISO speed).
- The APEX system (Additive System of Photographic Exposure), which defines exposure value.
- Frédéric Michaud, Société Astronomique du Havre: the NPF rule for star photography.