Formula
The hyperfocal distance sets the scale. H is focal length squared, divided by aperture times the circle of confusion, plus the focal length:
near = H × subject / (H + subject − focal)
The far distance uses a minus in the denominator. Distances inside the formula are millimetres. The crop-factor page does not use an aperture.
Assumptions
- The circle of confusion is the blur you still accept, in millimetres.
- The lens is focused at the subject distance.
- A far result past the hyperfocal distance is reported as not finite.
Worked example
A 50 mm lens at f/8, focused at 5 m with a 0.03 mm circle of confusion, is sharp from 3.39–9.49 m.
Input definitions
- Aperture
- The f-number. Larger numbers are smaller openings and more depth.
- Circle of confusion
- The blur diameter treated as sharp. 0.03 mm is a common full-frame planning value.
Limitations
This is a planning figure from the numbers you type. It is not a measurement of a network, a camera, a printer, or a power supply.
Questions
What does past hyperfocal mean?
The subject is far enough that the far limit of sharpness does not land at a finite distance in this formula.
Is 0.03 mm required?
No. It is the example. A different sensor or a stricter print can use another circle.