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Archive for July, 2010

How do I take blurry background pictures?

My first SLR was an ego purchase. Rich people around me that had rich people cameras were taking pictures that looked as though they’d been through years of photography school. My trusty Canon point-and-shoot may have been resiliently tolerant of my clumsiness and seemingly genetic predisposition to drop it into the unforgiving hands of concrete sidewalks and half full pint glasses, but it took little more than sharp colorful pictures. I envied my friends to could take those awesome pictures with a subject sharply in focus and everything else artistically blurred out. Turns out that even inexpensive, entry-level dSLR’s and manual point-and-shoots can give you the same effect.

This whole phenomenon is called “depth of field,” of which there are two ends in the spectrum.

“Great” depth of field:

In this sense the word “great” is not some morally indicative epithet or insightful scholarly suggestion, rather it’s a more graceful way to refer to a depth of field that’s, well, deep (as opposed to shallow). Everything is sharp no matter how far it is relative to anything else in the frame.
Great Depth of Field

Shallow depth of field:

Blurry backgound, blurry foreground, only your subject is in crisp focus. Looks cool and artsy and makes your friends that spent loads on Ashton Kutcher’s Coolpix pocket point-and-shoot jealous.
Shallow Depth of Field

So what controls depth-of-field? Well, you see, it’s quite simple . . . {external link to complicated science content that will take a physics degree to completely command}. Let’s translate that whole site into two very simple principles:

  • Zoomed in = long focal length = shallower depth of field = blurry background
  • Low f-stop = wide aperture = shallower depth of field = blurry background

So to really get acquainted with the technique, I suggest the following exercise. Set your camera to Av (aperture priority) mode, and crank down the f-stop as far as it will go. Next zoom the camera in as far as it will go. Then, without touching anything but the “take-a-picture” button, start snapping photos of things that are at various distances from you. Get your roommate/sibling/soulmate/etc. to stand five feet in front of you and snap a provocative headshot. Then have him/her move back to 15 feet and repeat. Then 25 feet, and so on. You get it. See the difference? Then you can zoom all the way out and crank up the f-stop. You’ll find it much, much harder to get a picture with shallow depth of field.

Newer Canon dSLR’s like the 50D and the T1i have a preview button that let’s to see what the picture’s depth of field will look like when you snap it. Any way you spin it, shallow depth of field pictures look cool and aren’t hard to take. Go ahead and see for yourself.