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Photography guides
The theory behind each calculator, explained with real numbers and diagrams — and the practical settings to use in the field.
- Depth of field explainedWhat depth of field really is, the four things that control it, how the sharp zone splits in front of and behind your subject, and practical settings for every genre.
- Hyperfocal distance: focusing for front-to-back sharpnessWhat the hyperfocal distance is, how to calculate it, how to focus at it in the field, and when to focus beyond it or switch to focus stacking instead.
- The exposure triangle explainedHow aperture, shutter speed and ISO work together, what a stop is, how to calculate equivalent exposures and EV, and which setting to prioritise for each kind of photo.
- ND filters and long exposures: a practical guideHow ND filters work, what ND8, ND64 and ND1000 mean, how to calculate long exposure times, a step-by-step daylight long exposure workflow and fixes for common problems.
- Crop factor explainedWhat crop factor means for APS-C, Micro Four Thirds, 1-inch, medium format and phones: equivalent focal length, equivalent aperture, depth of field and noise.
- 500 rule vs NPF rule for sharp starsWhy stars trail, how the 500 rule and the NPF rule calculate the longest exposure, why the 500 rule fails on modern sensors, and a workflow for sharp Milky Way photos.
- The depth of field formula, with worked examplesThe depth of field formula step by step: hyperfocal distance H = f²/(N·c) + f, near and far limits, circle of confusion by format and three fully worked examples.