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Depth of Field

JohanJohan Member
edited October 2013 in technique & style & stuff

On manual lenses, there (usually) is a little window showing the distance to subject that it was focussed on. Then, on the lens barrel around this window, extending to both sides of the focus point, were engraved the available apertures (typically in full stops), sort of a little ruler or scale if you like. The idea was that you could focus on your subject, and then, when you look at the little window, you could read of near and far limits of the focus field for each aperture (using the scale) allowing you to make an appropriate aperture selection for the required DoF. (There was also an easy way of working out the hyper focal distance using this scale).

In modern autofocus lenses, the little window (mostly I think) still exists, showing you the distance to the point it's focussed on, but the aperture scale is missing.

So, my question to you guys is, how do you know what DoF your selected aperture is going to result in? I know you can stop down the lens to see but that's awfully hard to judge since everything goes dark. Experience helps, but there are an awful long list of variables; Aperture, Circle of Confusion, Focal Length and Focus Distance, that has bearing on the DoF.

How do you make an informed decision every time, when you're under pressure? Niel? Some magic sauce please.


  • My $0.02 is to employ your experience, judgement, and trial & error. There are depth of field calculators on the web and even phone apps you can get. Here is a calculator on the web I use every now and then:
  • jan1215jan1215 Member
    edited October 2013
    You can always use the Live View function, or the Depth of Field preview button on the front of the camera by pressing it while looking through the viewfinder. It isn't perfect but it gives you a rough approximation of your DOF.

    See here:
  • Nikonguy said: My $0.02 is to employ your experience, judgement, and trial & error. :
    My thoughts exactly...
  • Neil vNNeil vN Administrator
    edited October 2013
    Johan ... I work in three broad ranges.

    I want shallow depth-of-field ... f/2.8 or wider. Or f/3.2 .. or f/3.5
    Somewhere there. Wide, or wide-ish.

    Then there's medium depth-of-field ... f/5.6 or f/8 .. somewhere there.
    Useful for two people, more or less in the same plane of focus.

    Then there's lotsa depth-of-field .... f/11 or smaller.
    Landscapes. Deep scenes where everything needs to be in focus.

    This is how I've distilled DoF for myself in a practical way.
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