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Depth of field (DoF) is the range of distances in a scene that appears acceptably sharp when a camera is focused at a particular distance. The plane of focus is sharpest; sharpness fades gradually in front of and behind it. The range counted as “acceptably sharp” depends on how the image will be viewed, not on a hard optical boundary.
How depth of field works
A lens brings points at one subject distance into the sharpest focus on the camera’s sensor. Points nearer to or farther from that plane form small blur spots instead of perfectly sharp points. If those spots are small enough for the intended image size and viewing conditions, the objects can still look acceptably sharp.
The circle of confusion is the blur-spot threshold used to estimate that acceptable range. The nearest and farthest distances that meet the selected threshold are the near and far depth-of-field limits. Change the threshold—for example, by changing the expected print size or viewing distance—and the calculated limits can change too. Depth of field therefore describes perceived sharpness under stated assumptions, not a guarantee that every point in the range is equally sharp or pixel-perfect.
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Aperture
A wider aperture, represented by a smaller f-number, generally produces shallower depth of field. Stopping down to a smaller aperture, represented by a larger f-number, generally increases it, all else equal.
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Focus distance
Focusing closer generally reduces depth of field at the same aperture. Focusing farther away generally increases it. This is why close-up subjects can have a narrow band of acceptable sharpness even when the aperture is not especially wide.
Focal length, framing, and magnification
Focal length matters, but it does not determine depth of field by itself. In a common portrait comparison, a longer lens may make the background appear more blurred because it has a narrower angle of view and the subject is rendered at greater magnification. The result also depends on framing and subject distance. To compare two setups fairly, consider the focal length together with the distance, magnification, aperture, and framing rather than treating “longer lens” as a universal rule.
Camera format and viewing conditions
Depth-of-field calculations use an acceptable circle-of-confusion assumption. That criterion is tied to the camera format and to how large and how closely the final image will be viewed. A depth-of-field calculator’s result is useful for planning only when its assumptions are appropriate for the intended output.
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How to get more of a scene in focus
- Use a smaller aperture (a larger f-number), if the scene and exposure allow it.
- Focus farther from the camera when the subject and composition permit.
- Choose framing and focal length with the desired subject magnification in mind; changing focal length alone does not guarantee a particular depth-of-field result.
- Judge sharpness at the size and viewing distance that matter for the final image.
These are general relationships, not isolated controls: the final result depends on the combination of aperture, focus distance, focal length and framing, format, and the acceptable-sharpness criterion.
Depth of field versus depth of focus
Depth of field refers to acceptable sharpness across distances in the scene, or object space. Depth of focus is a different optical concept concerning tolerance at the image or sensor plane. For a photographer asking which parts of a scene will look sharp, the relevant term is depth of field.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Where hyperfocal distance fits
Hyperfocal distance is a planning reference used to estimate the near and far acceptable-focus limits for a particular setup. It is not a separate kind of depth of field, and its result depends on the lens and the chosen sharpness assumptions. A calculated range should be treated as an estimate for the specified conditions, not as a sharp boundary that applies to every output.
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