Circle of confusion

Definition

The circle of confusion (CoC) is how large a point source may smear on the sensor before you call it unsharp. A working stills default is diagonal / 1500 (about 0.030 mm on full frame, 0.019 mm on APS-C). Tighter divisors (1730, 2000) match pixel-peeping or big prints; looser ones match small web JPEGs. Every DoF and hyperfocal number is only as honest as this CoC. Pick the viewing, then pick the circle.

Calculators that use this

• Optics & depth of field

  Circle of Confusion Calculator

  Get a working CoC from sensor width and height using the 1/1500, Zeiss 1/1730 or 1/1000 diagonal conventions for DoF and hyperfocal math.

• Optics & depth of field

  Depth of Field Calculator

  Work out hyperfocal, near and far sharp limits from focal length, f-number, focus distance and circle of confusion. Metres native; toggle feet on location.