Q My boyfriend used his digital SLR camera to take a really nice picture of my nephew standing by a fence. What made it look so nice was that my nephew was in focus but the background was fuzzy and soft. How can I do this when I take pictures?

COURTNEY SALVINI, WASHINGTON, PA.

A You can control how much of the foreground and background is in focus (called "depth of field") by changing combinations of zoom and aperture lens settings.

Wide-angle lenses and zoom settings create lots of depth of field, as do small f-stop settings. Although called "small" because the lens iris is small, this corresponds to the higher numbers.

Telephoto lenses and zoom settings, as well as larger f-stops, limit depth of field. So, to create a portrait with your nephew in focus you would set your lens at a telephoto setting and use the lowest f-stop that you can for the lighting conditions.

Also, the closer you are, the less depth of field you have. When photographing a group always focus one-third of the way in. Use a wide-angle lens setting and a smaller f-stop to maximize depth of field and get everyone in focus.

Finally, the size of a camera's sensor has an impact. Larger sensors have less depth of field and small sensors have tremendous depth of field. Digital SLRs and micro four-thirds cameras have large enough sensors that you can exercise considerable control over depth of field. Most compacts have tiny sensors that have so much depth of field that you get almost everything in focus no matter what you do, unless you have an ultra-zoom camera and use it toward the end of the zoom range. If you have a compact you might not have adjustable f-stops anyway, so just use the portrait setting for portraits and use the zoom at the end of its range if you want a fuzzy background.

Q I want to replace a single-disc CD player I use in an audio-only stereo system. Why don't I see component CD players for sale in big-box stores anymore?

G. MARKS, ATLANTIC CITY, N.J.

A You can still buy simple CD players, but you won't usually find them in mass-market stores. Because Blu-ray players and DVD players also play CDs and you can get a DVD player for less than $50, there isn't much incentive for manufacturers to make CD players for the mass market. Even if you only plan on using the CD-playing functionality, you are better off having the DVD playback available if you need it.

Some audiophile brands still manufacture dedicated CD players, but they cost much more than a typical DVD player or even a Blu-ray player found in a big-box store. You can find them in specialty hi-fi stores and online.

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