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Intrusion Exclusion

Using depth of field to minimize unwanted elements.

We’ve all been in a situation where we have the subject of our photograph framed just the way we like it but there is some element that is intruding either in the fore- or background. It could be a telephone wire, a tree branch, a rock, part or all of a person, a really busy background—just about anything that either competes for attention with or blends in with our subject and therefore is distracting and lessens the impact of our image. If a person is in the way, I usually just wait until they move. But if it’s something that isn’t going to move, then I have to move around to find an angle that eliminates the unwanted element(s) from the frame. Or I can change the focal length of my lens: use a wider lens to include the element and make it part of the composition or use a longer lens to exclude or minimize it. Like here, where I backed away and used a longer lens to soften the merchandise in this man’s shop (so he would stand out more from it).

But sometimes you can’t move. Or moving would change the composition so much that you would lose the image you were after. Or you can’t change the focal length of your lens (either putting on a wider or longer fixed-length lens or zooming in or out with a zoom) because that would destroy the composition too. That’s when being able to control depth of field comes in really handy. (To see how depth of field works, please see the “Sharp or Fuzzy? That is the question.” TipsFlick and Actual Info.)

Like the photos below. I wanted to make a photo of this beautiful flower, but there was an odd-looking, distracting big blob in the background. By using a slight telephoto (105mm) and getting close to the flower, I could throw that thing in the background so out of focus that it became a blur of color and did not distract too much from the beautiful object of the image. (Of course, Cary thought I was trying to get rid of the flower and focusing on him.)

As we talked about in “Sharp of Fuzzy,” three criteria determine depth of field: lens length (the wider the lens, the greater the depth of field), aperture (the smaller the hole, the greater the depth of field), and distance between lens and subject (the farther away, the greater the depth of field). (And vice versa for all of them.) Here’s how it works:

Long lenses:

It’s easy to get rid of distracting elements with long lenses because they have such shallow depth of field and because you are most likely shooting with a pretty fast shutter speed (and therefore a large aperture). It’s hard to avoid camera shake with long lenses if you are hand-holding at slower speeds, especially if you are photographing something that might eat you!

Shallow depth of field is really important to remember if people are posing for you. You could easily get close to them and use a fairly short lens (50mm or so). But is the background distracting? If it is, move back and use a longer lens to soften it up. Your subject will stand out better. Like the photo at left. The man obviously knew that Cary was making a picture of him, and Cary could have stood much closer. But the shallow depth of field gives the image much more impact.

Wide angle lenses

are trickier because they have such great depth of field at just about any f-stop. It’s just hard to throw things out of focus. If you can’t go to a longer focal length, the best thing to do is get as close as you can to the annoying thing and throw it out that way.

Notice how being close to the flamingo and using a wide f-stop made the chicken wire almost disappear and also softened the tree and annoying pole in the background. (I changed lens length in the photos to keep the flamingo about the same size in the frame.)

The most important thing to remember is this: Look carefully at your frame—all of it, not just your subject. Is there anything in the frame that doesn’t belong there, that’s annoying or distracting? If so, get rid of it either by moving (sideways, up or down) or by using depth of field. You’re subject should really pop!

All Actual Info and TipsFlix