This article has been updated since it was originally published to reflect changes in the market. Last updated on March 20, 2014.

Congratulations! You’ve taken the truly giant photographic leap to an interchangeable lens camera. Sure, compacts had their place and time but now it’s time to spread your picture-taking wings. What follows is a buying guide to your new camera’s most critical accessories—optional lenses.

Shopping around for your next interchangeable lens camera? Check out our picks for the best digital cameras, browse our digital camera reviews or see our digital camera buying guide.

Your First Step

We know you’ve done your most of your homework before purchasing your new camera. However, make sure you’ve checked out your camera lens options before pulling the trigger. We don’t expect you to buy 10 pieces of glass for your new camera body but whichever model you pick, make sure the manufacturer has a wide range available—from wide angle to telephoto and everything in between.

When you buy an interchangeable lens camera you’re entering a relationship with the specific hardware mount determined by the brand. For example, Nikon uses F and CX mounts, Canon EF and EF-S, Sony A, E, and F mounts, etc., depending on the type you choose. And while they are all interchangeable lens cameras, you cannot use Nikon glass on a Canon and vice versa. Yeah, we know this is very basic but it’s really important you know your options.

Beyond the Basics

DSLRs and mirrorless cameras are sold in “kits,” meaning they are typically supplied with an 18-55mm lens. This may sound impressive but realize this is only a 3x zoom ranging from about 27-82.5mm in 35mm terms. Compare this to a compact $349 Canon PowerShot SX700 HS with a 30x zoom (25-750mm) and you’ll soon realize you’ll have to spend a lot to match that focal range. Comparing a DSLR to a point-and-shoot isn’t really fair since the quality and capability of interchangeable lens cameras is so much greater—never mind all the other pluses—but we just want you to be prepared for some initial shocks.

The Numbers Game

Now get ready to use the calculator on your smartphone. Although a lens’ stated focal length may be 18-55mm, 50mm, 18-105mm and so on, the 35mm equivalent—what you actually capture—is impacted by the size of the imaging sensor. This is called the digital factor. In the case of most DSLRs using APS-C sensors, this number is 1.5x or 1.6x. That’s how we got the 27-82.5mm 35mm equivalent for the standard kit lens (18-55 x 1.5). Now this number varies with each make/model. Olympus and Panasonic Micro Four Thirds cameras have a 2x factor, Nikon 1s are 2.7x, Pentax Q is 5.5x and so on. The only instance where the stated lens focal length is one-for-one are DSLRs with Full Frame sensors such as the Nikon D610. Since the imager is the size of frame of 35mm film the lenses are direct equivalents. Full Frame DSLRs are wonderful but the price of entry is very high at $2,000-plus.

Zoom and Prime Lenses

The vast majority of interchangeable lenses are zooms. Their convenience can’t be beat as one piece of glass offers a wide range of focal lengths. Beyond the basic 3x there are 7x and 12x editions that we highly recommend. You’ll see figures like 18-125mm or 18-200mm, 55-210mm and so on. So multiplying the common digital factor of 1.5x, you can take wide angles of 27.5mm or 350mm telephotos (depending on your choice, of course). Having this flexibility is great since you don’t have to swap out lenses to capture the image you want.

There are loads of zoom options; just check the manufacturer site for details and prices. And don’t be afraid to venture beyond the name on the front of your camera. There are third-party brands available (Sigma and Tamron, for example) that offer quality, lower-cost options.

Prime lenses are also known as fixed focal length glass. This type is typically for those who are fairly well-versed in photography. They have a style of shooting they like and prefer that vision. A classic instance is a 50mm prime that is well suited for portraits as it comes close to the classic 85mm portrait lens. Recently we used a 28mm prime on a mirrorless camera and loved the results. Again this is our point of view but you could love 8mm fisheyes, 14mm wide angles, 60mm macros or 500mm telephotos. Again it all depends on your subject matter and style of shooting.

Open Wide

As you start searching for lenses you may do several double takes when you start comparing prices. You may see one 50mm for $120 and another for $1,600 from the same manufacturer. The key difference is the aperture or how wide open the lens can go—this is measured by f/stops; the lower the number, the more light you can capture. In the case of the $120 lens it’s f/1.8 while the more expensive one is f/1.2. The latter also uses higher-quality glass among other factors for the huge price differential. If you do a lot of shooting in low light without a flash, lower f/stops may be a crucial factor and a worthwhile investment. Also the lower the aperture rating the more of a blurring effect you can get for your backgrounds (called bokeh). Again this is a matter of style and vision. The lowest f/stop we’ve seen is a 50mm Leica lens rated f/0.95 that costs a cool 11K. Yes that’s absurd but we just wanted to show you the impact of wider apertures on lens pricing.

Stay Steady

Many interchangeable lens cameras have image stabilization built into the body to help eliminate shaky shots. Any lens you attach to the camera will automatically be stabilized. Canon and Nikon–arguably the two largest sellers of DSLRs–do not offer this. If you want stabilization, you have to buy specific stabilized lenses. This is easy enough to determine as Canon labels them IS while Nikon dubs them VR. Other manufacturers use a variation of this nomenclature but it’s an important feature—especially if you shoot a lot of extreme telephotos.

We’ve just hit the high points as you enter the world of interchangeable lenses. You can delve much more deeply with research into glass quality and specific formulations. It can be a bit arcane but as far as we’re concerned, you’ve already taken the biggest leap of all, simply by purchasing a DSLR or Compact System Camera. By all means don’t be intimidated and have lots of fun.

What do you think of our camera lens buying guide? Did we miss something? Let us know in the comments below.

(First image courtesy of cyther5/Shutterstock)