Whether you use a smartphone or a point-and-shoot as your primary camera, if you're serious about photography, all paths lead toward a digital SLR (single-lens reflex) model. With their large image sensors, interchangeable lenses and a seemingly endless supply of tweakable features, DSLRs maximize both flexibility and mobility. They look pretty hot, too.

Since the debut of the Nikon D1 in 1999 — the world's first modern DSLR — the technology has advanced considerably. Once for still pictures only, almost all DSLRs manufactured today record video, too. Camera makers have enhanced autofocus mechanisms with swarms of extra focus points and added high-tech features, such as face detection. Some even have swiveling LCDs for hard-to-get shots.

But those are extras. The reason you get a DSLR is so you can take great pictures. The large image sensors in DSLR cameras capture more light than those in smaller models, and they're paired with high-performing image sensors.

That lets many DSLRs shoot still photos in RAW format — which records all light data (except for direction, right Lytro?) with no compression. Shooting in RAW results in very large files, but it also ensures photographers get the most accurate pictures possible.

Finally, DLSRs are made to be the center of a photography experience that goes beyond the camera. Almost all have ports and jacks for accessories, and there's also a "hot shoe" on top, where you can attach powered items, typically an external flash. DSLRs are the gateway to building a photography arsenal, but they'll also take great pics on their own.

When you desire a new DSLR, the right camera depends mainly on what you're looking to do with it. Below, we outline some typical use cases and suggest a model for each situation.

The Graduate

You've liked the simplicity of point-and-shoots, but their limitations are starting to frustrate you more and more. You need something that performs better in low light and can capture fast motion when needed — with minimal blur. Still, you don't want to get overwhelmed by features.

Entry-level DSLRs were made with you in mind. Models like the Canon EOS Rebel T3 and Nikon D3100 have all you need to get started. Although they give the full-manual flexibility of any DSLR, they also have many simplified exposure presets. Just switch the dial to, say, landscape photography, and the camera will automatically configure its settings to capture a crisp shot of that mountain range.

Today, even basic DSLR cameras can capture HD video. But if that's not important to you, you can still find some cheaper older models, such as the Nikon D3000, which shoots stills only. But the ability to switch is a very handy feature, so there's a good chance it's well worth the extra coin to get a camera that does both.

The Videographer

Buying a stand-alone video camera almost seems anachronistic today. However, still cameras don't often make for the best video cameras. Because of differences in optics and image processing, cameras that are primarily used for taking stills often don't capture high-quality video. Fortunately, DSLRs have tremendous advantages over cameraphones and point-and-shoots in those areas, and can make excellent video cameras — as long as you know what to look for.

The Canon T3i and Nikon D5100 are great choices for budding videographers. Both capture video in full 1080p resolution, and that speedy image processing means they have good "burst" modes. Nikon also offers continuous autofocus while shooting video, keeping your target sharp as it moves (however, this usually results in noise from the servos getting captured).

Looking beyond the usual suspects, Sony's Alpha DSLRs have impressive video-capturing abilities, sometimes at a better price. The Sony Alpha a57 can capture 1080p video at 60 frames per second — Canon and Nikon cameras in its price range max out at 30. It also has nice bonuses, like a swiveling LCD screen and HDMI output for connecting to a big-screen TV (also available on the D5100).

The Upgrader

If you have an older or lower-end DSLR and are looking to upgrade, there's lots to choose from. Going to a mid-level camera won't just improve your photos, but also the overall photography experience. With better image processing and bigger camera bodies, you'll enjoy faster burst mode rates and longer-lasting batteries, plus those swiveling LCDs become more common.

The Canon EOS 7D is an excellent choice for upgraders, able to capture full HD video and shoot up to eight still photos per second. "Prosumers" will love the 19-point autofocus system and the intelligent viewfinder, which is more graphically dynamic than previous models. If the 7D is a little on the pricey side for you, you might want to check out the 60D, which has many of the same features.

Nikon's mid-level DSLRs start with the D7000, which has two user-definable exposure settings, letting you instantly configure the camera for your most common environments. There's a 39-point autofocus system, and it can shoot up to six still pics per second. It also has continuous autofocus when shooting video.

Sony gives you great bang for your buck with its mid-level DSLR. The Alpha a65 captures pics with a massive 24.3 megapixels, and its Burst mode is an impressive 10 frames per second. Like the a57, it can record 1080p video at up to 60 frames per second, and you have full control of shutter speed and aperture while recording. The LCD can swivel, and the viewfinder is a high-resolution OLED screen that can show the results of camera adjustments in real time.

Finally, if you've broken more than one DSLR while shooting in extreme situations, the Pentax K-30 (due in July) is made with you in mind. It's fully weather-sealed, so it's up to the task of shooting on the beach or a mountaintop, and it can withstand cold temperatures and dust. It shoots 1080p video (30 frames per second) and can capture six stills per second in burst mode.

The Serious Photographer

If you want a taste of what it's like for pro photographers — or simply want the best of the best — you'll want a high-end DSLR. These are serious image-capturing devices that pour on the megapixels and customized settings. With so much tweakability, they often do away with some automatic features common on lower-end models (like exposure presets and a built-in flash) entirely.

The Canon EOS 5D Mark II is a great step toward true pro photography. Its full-frame image sensor can take 21-megapixel shots, and if your situation is less than ideal, you can improve your pics with features like an "Auto Lighting Optimizer" and "Peripheral Illumination Correction." If you have a little more money to burn, there's also the more recent 5D Mark III, which has better image processing and a few more tricks.

For Nikon, the D300s will get your feet wet with pro features, like in-camera image editing, a 51-point autofocus and nine customizable picture settings. But if its 12.3 megapixels aren't enough for you, cast your eyes toward the D800, the highest-resolution full-frame DSLR on the market, at 36.3 megapixels. Both capture 1080p video at 30 frames per second.

If you think you're ready for the extreme high end, you'll want either the Nikon D4 or Canon EOS-1D X. Both have too many features to summarize well here, but each will satisfy the pro within you. Their bulky camera bodies provide lots of extra power and a convenient handgrip for portrait shots, but that also means they're not for casual shooting.

What's Your Shot?

Buying a DSLR is a lot like buying a computer or a car — it's a commitment to both a product and a company. It's not to be taken lightly, but if you can match the right model with your goals, it'll unshackle the shutterbug within you and you'll soon be taken better pictures than you ever have. We've covered just some of the options here — there are lots more to explore, so browse the web, visit your local camera shop and find your perfect model. Once you go DSLR, you'll never go back. What's your model? Let us know in the comments.

Image courtesy of iStockphoto, by_nicholas