Is there a formula to calculate DOF?

  • I am pretty clear about that DOF depends on:

    1. Focal length
    2. Aperture or f-stop
    3. Distance from subject
    4. Sensor size

    and more (as pointed out in this comment).

    But my question is: Is there any formula that relates all these factors with Depth of Field?

    Given these values is it possible to accurately calculate the Depth of Field?

    There are two more things to consider: (5) the size of the final image; and (6) whether you are concerned with the "zone of acceptable sharpness" when the other five factors are taken into account, or with the "zone of sufficient blurriness".

  • Matt Grum

    Matt Grum Correct answer

    9 years ago

    Depth of field depends on two factors, magnification and f-number.

    Focal length, subject distance, size and circle of confusion (the radius at which blur becomes visible) jointly determine the magnification.

    Depth of field does not depend on lens or camera design other than the variables in the formula so there are indeed general formulas to calculate depth of field for all cameras and lenses. I don't have them all committed to memory so I'd only be copying and pasting from Wikipedia: Depth of field.

    A better answer to your question would be to go through the derivation of the formulas from first principles, something I've been meaning to do for a while but haven't had time. If anyone wants to volunteer I'll give them an upvote ;)

    That's somewhat mixed up. Magnification is just determined by the ratio of focal length to subject distance. Magnification and f-number determine at which rate depth relative to an object's width grows into blur relative to the object's width. To determine actual depth of field, you need to define just what size of blur you still consider in-focus: that's essentially the circle of confusion.

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