The simplified Formula of Depth of Field

The common photographer knows that the Depth of Field varies with the aperture, focal length and subject distance. But which one is the dominant parameter ? And how much is the influence of each parameter ? This article uses the equation of the DoF, and demonstrates that when the DoF is short, it varies proportionally with the aperture, and with the square of the focal length and distance to subject.

So here comes the only formula you need to know when you deal with short DoF but not macro photography :

- A is the aperture number
- c is the circle of confusion
- f is the focal length
- s is the subject distance
- H is the hyperfocal distance
- DoF is the depth of field

In the rest of the article you can read where this simplified formula comes from, what it means in practice, and how accurate it is compared to the exact formula of DoF.

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