Photography Calculators

Optics & depth of field

Circle of Confusion Calculator

DoF calculators are only as honest as the CoC you feed them. This takes the sensor rectangle, builds the diagonal, and divides by a viewing convention. 1/1500 is the usual full-frame print CoC; 1/1730 is the stricter Zeiss figure; 1/1000 is looser for web-sized files.

Inputs

Units
mm

Photosensitive width, not the body throat. Full frame is typically 36 mm.

mm

Full frame is typically 24 mm. APS-C is around 15–16 mm tall.

Smaller divisor → larger CoC → more reported DoF.

Results

Sensor diagonal
43.267mm

Sensor diagonal in millimetres.

Circle of confusion
0.0288mm

Circle of confusion in millimetres; full frame is often 0.030 mm.

The Result is indicative and educational. It does not constitute a design, a technical opinion or medical advice and does not replace calculations or verification by a person with the appropriate qualifications and authorisations. Before purchase, installation or use in practice – in particular in electrical installations – the Result should be verified by a qualified specialist. Details: Terms of Service, point 4.

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Calculation method

Sensor diagonal is the hypotenuse of width and height. Circle of confusion is that diagonal divided by the convention you pick: 1500 for a standard enlarging CoC, 1730 for the stricter Zeiss figure, or 1000 if you only look at small web images. Full frame at 1/1500 is about 0.029 mm, which is why 0.030 mm is the usual round number in DoF tables.

Exact formula

diagonal = √(w²+h²). CoC = diagonal / divisor. Limits: Divisor is a print/viewing convention, not a photosite size; pixel-peeping and huge prints want a smaller CoC than 1/1500.

Format cheatsheet

Full frame 36×24 mm at 1/1500 ≈ 0.029 mm. APS-C ~24×16 mm ≈ 0.019 mm. Micro Four Thirds 17.3×13 mm ≈ 0.014 mm. Those are the numbers this site’s camera presets use, rounded.

DoF tables from the film era

Old lens barrels assume a CoC around 0.030 mm and 35 mm film. On a 40 MP APS-C body viewed at 100%, those marks are optimistic.

Frequently asked questions

Is CoC the same as pixel pitch?

No. Pixel pitch is how big a photosite is. CoC is how large a blur spot you still call ‘sharp’ on a print or screen. High-MP bodies can use a smaller CoC if you pixel-peep.

Which divisor should I pick?

1/1500 if you print or view like a classic 8×10. 1/1730 if you are picky. 1/1000 if the file lives on a phone. Be consistent across DoF and hyperfocal.

Do I change CoC when I crop in post?

If you crop hard, you are viewing a smaller piece of the sensor at the same output size, so the effective CoC shrinks. Recalculate or expect less usable DoF.

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