Digital SLRs give you lots of ways to expand your shooting capability. (Sony DSLR-A700 pictured)

Along with the detailed images digital SLRs provide, photographers are also discovering another great aspect of these cameras — the impressive array of gear available to expand their camera's performance and capability. Of course, many items such as cases, batteries, and memory cards are "gotta haves" for all digital cams. Others, such and lenses and add-on flashes, are generally unique to SLRs.

Whether you're looking to capture images of wildlife across great distances, freeze detailed close-ups of a hummingbird in mid-flight, or take professional-looking portraits of your family, there's SLR gear to help. In this article, we'll cover some important equipment basics.

The right carrying case will protect your camera and hold all of your gear. (Tamrac Aero Speed Pack 75 pictured)

A case or backpack for your camera

A good carrying case can extend the life of your camera by protecting it against bumps, scratches, dust, and weather. It also lets you stow and organize important items — such as your battery charger, cables, memory cards, and lens cleaner — so they'll be handy when you need them. And it provides safe storage when your camera is not in use.

If you're just starting out, you may find that a smaller case is sufficient to keep your stuff together. You can choose from simple padded cases with enough room for a spare battery and memory cards, or something a bit larger that's capable of accommodating an add-on flash and an additional lens or two. For long treks with lots of gear, backpack-style cases make an excellent choice — they help distribute the weight more evenly to provide greater comfort.

Some of the things to look for in a case are:

• a carrying handle on top (or even a belt loop for smaller bags) for convenient toting

• a padded, adjustable shoulder strap for comfort

• adjustable interior compartment dividers that let you arrange and customize the case for your specific gear

• zippered exterior pocket(s) to keep small, frequently used items handy

• additional pockets for larger items and owner's manuals

• enough room to comfortably accommodate your SLR with lens attached

SLRs can capture big detailed photos, so be sure to get plenty of memory for storing them.

Memory cards

Like most digital cameras, digital SLRs use removable flash memory cards, such as a CompactFlash™ or Secure Digital® card to store digital photos. Be sure to check your camera's manual to make certain you're buying the proper type. Most digital SLRs don't come with any memory included, so that means you'll need to buy at least one card to get started. And you'll probably want to have at least a couple of spare high-capacity cards to ensure you don't run out of storage space while you're shooting. SLRs can capture such detailed photos, you might find your memory card filling up more quickly than it did with your point and shoot camera.

The chart below shows the number of photos that a 1GB memory card can hold when being used with a typical 10-megapixel digital SLR set at various image quality levels and sizes. Remember, many photographers prefer to use the highest quality settings and largest image size at all times to ensure the best possible pictures. The resulting image files can take up a lot of memory space quickly, so it's always better to have more than you think you'll need.

Memory cards also vary in how quickly they can record picture information. The measurement of this ability is known as write speed or image transfer rate. The numbers are usually expressed in megabytes (MB) per second, or sometimes with numbers like 80X, 133X, 300X, and so on. The higher the numbers, or the more megabytes per second, the faster (and frequently the more expensive) the card.

Why is this important? A card's ability to write images quickly can affect the performance of your camera's continuous or "burst" shooting mode. If you plan on taking a lot of rapid-fire shots in burst mode, you should keep an eye on the cards write speed.

If you're covering important occasions, like weddings or family reunions, a single ultra high-capacity model (an 8GB for example) lets you avoid having to swap cards during critical moments. This also provides the comfort of knowing that you can keep shooting lots and lots of photos without worrying about running out of space. On the other hand, if you're on a vacation trip you may want to spread your photos out over several smaller cards, storing each card in a secure location apart from the camera. That way, if anything happens to your camera or one of your cards, you'll still have the photos on your backup cards.

Vertical battery grips extend shooting time and provide better control of your SLR. (Canon BG-E6 shown)

Batteries

All digital SLR cameras come with a proprietary rechargeable battery that's capable of taking hundreds of shots on a single charge. For general all-around shooting close to home, that's probably fine. But if you plan on long days of shooting without time for a recharge or access to electricity, or you're photographing a once-in-a-lifetime event, you'll want at least one extra battery charged and ready to go.

Some SLRs also have compatible "battery grips." These attach to the base of your SLR, and give you a more comfortable handhold when taking vertical shots. As the name implies, they also provide additional power to your cam, either using your cam's proprietary battery or multiple "AA"-size batteries.