Saturday, January 2, 2010

Focal Length and Aperture

Shallow depth of field must have been designed with babies in mind. See the soft edges just beyond his little ear? It helps to bring your attention right to his darling little sleepy face.

The next image was shot with our little guy in the same position, I simply moved above him. (Yes, I posted this photo the other day but I wanted to illustrate a point so I'm showing it again.)

Notice how this image is sharp from his ear to the ottoman he's laying on? Would you believe they are shot at the same exposure? It doesn't take long for most beginners to catch on to how to control depth of field. Wider apertures equal less depth and smaller apertures equal more depth. But there is one factor they often forget to consider: focal length.  The lens you use controls more then how close or far away the subject is, it also controls the compression of the subject in relation to the background. Read up on optics if you wish to know exactly how this works (and you should know!) I mention this only because I get asked a lot about what exposure I should use for a particular shot.But there isn't one exposure that fits every scenario, instead is a conglomeration of multiple factors that decides how your image looks. A number of scientific and mathematical principles are applied every time the shutter is pressed. The "art" is when you can decide and adjust those equations to achieve your desire results. Image 1 is shot with a 50mm prime. Can you guess the second lens? Hint: I've mentioned in earlier blog posts what my favorite lens to shoot with is.

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