Face Detection With this mode turned on, your camera locates the people in a shot and then fine-tunes the focus and exposure for those faces. While this may sound like a superficial gimmick, we've found that it works surprisingly well—greatly increasing your chances of getting good shots at a wedding or family reunion. Typically, this option is in the camera's autofocusing (AF) menu. Face detection is particularly handy for candid shots, where you're working quickly and are thus more vulnerable to misfocused shots. It's also a boon for flash photography. With face detection turned on, the flash doesn't try to illuminate the whole room, just the people within range—cutting down on the nuclear blast effect.
Storage If you have an existing storage card that you'd like to use with your new camera, make sure that it's compatible with your new purchase. Most cameras on the market today use SD (Secure Digital) or SDHC (Secure Digital High Capacity) format cards. SDHC (Secure Digital High Capacity) cards are more expensive, offering increased storage capacity up to 32GB, but they're not backward-compatible with standard SD slots. SDXC, which supports storage capacities up to a whopping 2TB, are even more expensive and they aren't compatible with all SD/SDHC card slots.
Video Many DLSRs offer video recording features—often at HD resolution. You'll have to make some usability compromises that you wouldn't have to make if you used a camcorder but the video quality is often worth it. And because you can take advantage of a variety of lenses, including fish-eye lenses, you can achieve interesting video effects with an SLR. Remember that video requires a lot of storage space, so plan accordingly.
In addition to storage capacity, there's also the speed issue to consider. SD and SDHC cards have a Decoding Class rating listed, which refers to the data-writing rate for each card. The higher the Class number, the faster the write speed; if you're planning on shooting video or using a high-speed burst mode, look for a Class 4 or Class 6 card at the very least.
To complicate matters further, there are a couple of other card formats out there. Some cameras support MicroSD or MicroSDHC cards, a smaller version of the SD card format that isn't compatible with full-size SD slots. Older Sony cameras take MemoryStick cards, and older Olympus cameras use the XD card format; both companies' new cameras now support SD/SDHC cards. What's more, many higher-end DSLRs have a larger-format CompactFlash card slot. You'll want to consider all of these options when purchasing storage for your camera, though it is definitely easiest to go with standard SD/SDHC cards since you will be able to use them across cameras.
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