Apr 5, 2009

Depth of Field Primer

As I've discussed before here, controlling background clutter and isolating your subject is absolutely crucial to making good pictures.

Getting that "fuzzy" background look can really make a picture pop, and it definitely pulls you out of snapshot territory.

Controlling how much of your photo is in focus comes down to two main things...

Camera to Subject... if you get closer to the subject, the background will get more out of focus. Seems simple enough, but it has to do with the physical distance, not zooming in. Get close!
Subject to background... the further your subject is from the background, the more out of focus the background will be. For example... if your subject is leaning on a wall, it will be hard to get the wall out of focus. Bring the subject for a little separation, and good things will happen. You also start to get layered composition this way, which is good.

Here, getting close to the bird was a pain, and I probably looked a bit goofy chasing it around with the camera... But it has a nice blurry background. Of course, the bird was getting a bit concerned about my intentions.
what are you lookin' at?

This is easiest to control on an SLR camera... Smaller Aperture number = less amount of in-focus area. This is "Shallow" depth of field.

Here is a series of shots from a Canon 5D with a 50mm lens for demonstration...

The point of focus is the near side of the fourth (light orange) spool of thread. Look as each aperture change brings more depth into focus... eventually at f22, even the texture of the wall behind is clearly visible.

On a side note, at f11 and f22, you also see the dirt that has accumulated on my camera sensor... time for a cleaning!

Now what do you do with that information?

For Point and Shoots.... you need to get close, and, use the "portrait" setting. This will get the shortest depth of field available. For a variety of technical reasons, P&S cameras have a hard time getting short depth of field, so distance is what you have to work with most.

For SLR users... Try the Av (Aperture Priority) setting. With that, you are in control of how much depth of field you are using. Knowing that you can knock the background out of focus (or keep it clear if that is what you want), is a very powerful option.

In Aperture Priorty (Av) mode, you set your aperture, and the camera will adjust the shutter speed to compensate. It is almost exactly like shooting in all-auto (Green Square) mode, but you start to take control.

Most importantly, you have to practice with your camera so that when you want to control something like this, you already know what to do.

Happy Shooting,

Don J

1 comment:

  1. Good stuff today! While the Pigeon looks ready to attack I like it. You managed to capture expression in an animal.