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
Circle of confusion
0.0288mm

Recommended gear

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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