Depth of Field

Technical Articles | By: indie

The depth of field in an image is the portion of it that appears to be sharp and crisply in focus. In this tutorial I’ll explain depth of field and demonstrate how you can use varying degrees of it to add interest to your shots.

Later, I’ll show you some examples of depth of field that contain wide vs. narrow depth of field comparisons.

This technique works by giving visual priority to the subject you want your audience to focus on. If you want them to see everything your image has to offer and give each object equal importance, the whole image should be in focus and therefore you should use a wide depth of field. If there is a single object, person, or group that take precedence over all else in the image, using a narrower depth of field will help to draw the viewer’s eye to them.

Wide Depth of Field

In order to shoot with a wide depth of field, your camera’s lens needs to be set at a wide angle, and you can achieve this by simply zooming all the way out.

Shots where you have multiple objects whose distances from the camera vary greatly, such as landscapes and horizons, are best captured with a wide depth of field. You can bring out your depth of field to literal infinity with a wide angle lens configuration this way, but using a narrower field will lend a degree of polished professionalism to your work.

Narrow Depth of Field

If you want to focus in on a particular subject, your image will look more natural if you use a narrow field depth. To narrow your depth of field, dolly back, away from your subject, and then zoom in.

A camera lens that is zoomed in is said to be in telephoto mode as opposed to wide angle mode. While zoomed in, every movement of the camera affects the frame to a larger degree, so it becomes especially important to maintain a steady shot when in telephoto.

After you have set up a shot with a narrow depth of field, it’s important to make sure your subject stays in focus. Movement toward or away from the camera could put the subject out of focus quickly, depending on just how narrow your field depth is.


Comment from Eric Barker
Time: August 12, 2011, 8:55 pm

Technically, the notion that backing away from a subject to create higher depth of field IS FALSE. Changing focal length does nothing to effect the actual depth of field. DoF can only be achieved by:

A) increasing the distance between subject and background
B) Widening the aperature (shooting at lower light levels and choosing a a larger f-stop)
C) Increasing the CCD/Film size
D) special lens adaption equipment

This is a common misconception, almost a “rule of thumb”. However, it is not completely without reason. The further away the camera is, the larger the background will appear compared to the forground subject. This means that a small blurry object in the background now becomes a big blurry object when zoomed in. The object becomes more visible, and the actual blur length becomes bigger (since the object itself is bigger), and we perceive it as being softer. But, if you were to then crop out the object and compare it between two shots: one close, and one telephoto, the blur would be identical.

A few years back, when I first heard this “rule of thumb”, I becames suspicious did some basic tests. But I only recently stumbled accross a blow-by-blow article with examples (this is a good read, very well done):

Now, in some ways, this is splitting hairs, because the end result of backing up will be the perception of softness, and for most of us, that’s reason enough to do it. BUT it’s NOT “depth of field” and it doesn’t achieve the same type of separation you would find with a higher DoF.

Also, keep in mind that shooting telephoto means unnaturally flattening the image. Shapes tend to loose their depth, and distances between objects appear to be shortened. This is not to say, “don’t zoom in”, but if you want the forms along your z-axis to stand out, you’d probably want to avoid using super telephoto shooting, and simply move closer.

Comment from indie
Time: August 15, 2011, 1:27 pm

Eric – thanks for your comment, first of all. I understand your point, but since the majority of the articles on this site are meant for an audience who does not own high-end equipment, I try to focus on ways to achieve results with the types of cameras the average budget filmmaker has available to them. True, if you own a high-end camera that has manual ISO, f-stop, etc, you can create the appearance more easily. But for someone using a consumer-grade camcorder from Best Buy, for example, oftentimes literally the only way to get a DoF result that is somewhat film-like is to dolly back and go telephoto. Remember, this site leans sharply toward film making on a budget, so it would be presumptuous to assume that my readers have lens adapters or cameras with manual aperture settings.

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