One of the issues that frustrates many beginning photographers is how to control the background in their photos. Sometimes the background is not an issue, or is integral to the overall composition: most landscape photos fit this description; also photos with a flat subject plane (maybe an image of a building facade, for instance). But for many more images, having the proper control over your background can mean the difference between success and failure.
It can be a problem when too much of what’s in the photo is in focus: maybe you’ve shot a nice outdoor portrait of someone, but the trees behind them are in focus too, competing with your subject for attention.
In cases like this, depth of field is the key. The depth of field is how much stuff is in focus in front of and behind your focus point. The thing to remember: the smaller the aperture, the more stuff will be in focus, regardless of what focal length lens you are using. So for that outdoor portrait shot, pick a very wide aperture (f2.8 or f3.5, for instance) and balance the exposure with a faster shutter speed. This will result in a photo with a tack-sharp subject and a nice out-of-focus background (like my photo of the graduate above).
The flip-side of this example is true too: maybe you have an image in which you need the background in focus for the image to work. There’s subject matter back there that is part of the composition. So here, you’ll want to slow your shutter speed down and use a much smaller aperture: maybe 1/60 @ f11 or f16, for instance. This will help you retain discernible detail in more of the image.
In both cases, having proper control over depth of field is the key to controlling your background, and hence your composition.
Hi, I’m Andrew Boyd, a.k.a. The Discerning Photographer, and I hope this post has been interesting and informative. Please leave me a comment about it, let me know what you’d like to see more of on the site! You can also sign up for email delivery of all future articles or my RSS feed. Thanks!–DiscerningPhotog
Related articles on the web:
Three Ways to Control Depth of Field at Epic Edits
Dynamic Depth of Field at YourPhotoTips
Using a Shallow Depth of Field for Portraits at PetaPixel
17 Examples of Narrow Depth of Field at Lightstalking