Little tip

April 20, 2009

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This is a picture I took at a church, following the baptism of a friend’s child. Every once in awhile I get family or friends asking me how I take photos that have the background blurred out behind a particular subject. The name for this result is called “Depth of Field”, also referred to as DOF. DOF is controlled by various settings on the camera, but simply, a larger aperature opening produces a shallow DOF, and a smaller aperture produces a larger DOF. Take a look at this diagram for a graphic explanation:

depth-of-field-comparision1

So what is aperture? Aperture is the size of the opening inside of the camera’s lens. The size of this opening is controlled by a diaphragm that can change size to allow more or less light to enter the camera:

fstopsdiagram

The reason I am getting into this is because I was attempting to take a picture on Saturday where I experimented with DOF to take two different approaches to the same shot. Take a look:

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I was trying to play with their refidgerator magnets and have them show up in the shot, but I wasn’t sure if I wanted the couple to be in focus or out of focus. Both shots were taken with the same 50mm lens.  The first shot was taken with an aperature of F2.8 (larger opening) while the second was taken with an aperature setting of F13 (smaller opening).

Unfortunately, most point-and-shoot digital cameras do not give you  much control over these settings, but most do include a portrait mode (shown by a person’s head as an icon) which forces the camera to use a larger aperature to get the same effect. Some of the better point and shoot cameras do give you this control, and of course, an SLR camera will give you complete control. I hope this all makes sense to you. Try doing a test with your own digital camera, even if it is a point and shoot. Just put it in landscape mode (usually shows a tree and mountains symbol) and take a shot of say, a tree that has some sort of background behind it. Set yourself about 15 feet away from the tree. Next take the same shot, from the same location with the camera set to portrait mode. You should see a difference in how the background is focused. Have fun!

for more information on the various camera settings available, take a look here:

Camera Settings

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One Response to “Little tip”

  1. Claire said

    I don’t have a camera with which to play with such settings. But that first magnet photo is much more alluring than the second one (I think it’s the mystery and imagination in the blurry shapes)!

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