Photography
Hyperfocal distance
Focal length and aperture against the near limit of a deep focus.
Readings
Drag the red line, or type into any two boxes — the third is solved. The marked box is the one being solved for.
Print at 100% scale, then check the 100 mm bar with a rule before trusting a reading.
Why this one is an instrument
The useful question in the field is never "what is the hyperfocal distance" on its own — it is how much depth you buy by closing down two stops, and whether that is worth the shutter speed. The focal-length scale is squared, so it moves twice as fast as the aperture scale, and seeing that asymmetry directly is the whole lesson: changing lens costs you far more than changing aperture.
- Equation
- H = f² ÷ (N · c)
- Constants
- c = 0.029 mm (35 mm format)
- Ranges
- f 20–200 mm · N 1.4–22 f/
- Reading
- Any two values fix the third. Outside the printed ranges the instrument stops being valid — that is what the end marks are for.
These are drawn from the stated equation and nothing else. Where an equation is itself an approximation — hyperfocal distance and tap drill sizes both are — the instrument inherits that approximation exactly, no better and no worse.