Thursday, September 15, 2011

Depth of Field

Welcome back!

This time we're going to explore DEPTH OF FIELD, commonly referred to as DOF.

Have you ever noticed that some photos are extremely sharp all the way through the whole range of the image and some stop being sharp with only a small range truly sharp? This range of sharpness in a picture is DEPTH OF FIELD.

How can we control this? There are several tools at our disposal. One is controlling the distance between subjects, another is focal point (an upcoming post), but the most valuable to us, and the one we will discuss here, is our aperture or f-stop.

You might remember that aperture is the size of the "window" in the lens. You might ask, if it controls how much light gets in, how can it control the DOF?

With a narrow aperture, basically, the light becomes more tightly focused, making the DOF wider and allowing an increase in sharpness.

A couple words of caution on this:

1) This is not the cure all for poorly focused or blurry images. One negative side effect of a very small aperture, or large f-stop, is diffraction blur. The bending of light as it squeezes through the aperture causes this, and can make blur more noticeable.

2) This will require longer shutter speeds. Sometimes beyond your ability to hold a camera steady. Camera shake is really bad at long exposures!

So, if a narrow aperture will increase DOF, it makes sense that a wide aperture will decrease your DOF.

Now, it's time to break out your camera. Play with your DOF; adjust your aperture and your focus to get some images with a shallow DOF and some with more depth, or wider DOF. A great way to start is taking 2 items and placing them on your table at different distances from the camera. Shoot at the range between f4 and f16 and examine the results.

Don't you feel more artistic already? I did when I first tried it!

For more information on DEPTH OF FIELD, check out our Intro to Photography page and don't miss out on Cambridge in Colour's excellent in-depth tutorial.

That's it for this post. Here's hoping you have a great week and get some good shooting in this week-end!

And remember, if you have any questions or comments feel free to share them here or on our Facebook page.

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