SLR lens buying guide

An interchangeable lens is attached to a digital SLR via a locking mechanism called a "mount." Once it's mounted, the lens provides you with a specific "focal length." (Technically, that focal length is the distance between the lens' glass elements and the camera's sensor, which captures the image). The greater a lens' focal length, the closer it brings the subject you are shooting. A given lens is usually designed to work with just a single brand of camera. For example, a Nikon lens will fit a Nikon DSLR, but not a Canon. See the Brands section for more information.

A lens is like a tube filled with glass lenses that funnel light onto a digital sensor. The physical size of the lens, and the amount and shape of the glass will affect its focal length. A standard or "normal" lens, with a fixed focal length of 50 mm, has a horizontal angle of view that is about the same as what the human eye perceives. A longer lens, such as a telephoto, will bring you closer to your subject while a shorter, rounder, wide-angle lens will give you a broader perspective.

Some lenses, called zooms, provide a range of focal lengths that you can control as you shoot. Some of the most typical zoom lenses used with consumer DSLRs range from 18 to 55 mm to 24 to 85 mm. For shooting subjects at greater distances, there are telephoto zoom lenses, with ranges such as 70 to 200 mm. For shooting landscapes or other wide subjects, there are wide-angle zooms, with a range such as 12 to 24 mm. For the greatest versatility, there are ultra zooms, with ranges as great as 28 to 135 mm or 18 to 200 mm.

Because the image sensors on digital cameras are usually smaller than a frame of traditional 35-mm film, when a lens is used with a DSRL, you need to account for that difference by figuring its effective focal length. For example, a 50-mm lens on a Canon Digital Rebel would have an effective (or "equivalent") focal length of 80-mm lens when taking into account the camera's 1.6x magnification. Such magnification factors vary from one brand of camera to another, and sometimes even among models within the same brand.

Some higher-end digital SLRs use so-called "full-frame" sensors, which are about equal in size to a frame of 35-mm film. With such cameras, there is no lens magnification, or equivalent focal length. In short, a 50-mm lens remains a 50-mm lens on a full-frame sensor SLR such as the Canon 5D Mark II or Nikon D700.

If you just purchased a digital SLR, you might be wondering why you'd need to buy a lens if your camera came with one. It's true that most consumer digital SLRs are sold with a "kit" lens—typically a short standard zoom with a focal range of around 18 to 55 mm (28-to-85-mm digital equivalent)—which is cost effective, but not necessarily of the highest quality.
The problem with such lenses is that they limit what you can do with them creatively because they're usually not long enough to reach distant subjects such as wildlife and they're not wide enough to capture a broad perspective such as when photographing landscapes. Kit lenses are also not ideal for portraits because their focal lengths are shorter than what's preferred for portraits and their apertures aren't suited for blurring the background, which helps to draw attention to the person you're shooting. Kit lenses aren't as rugged or as sharp as more-advanced lenses because they're typically made of plastic rather than metal and glass. To see how some inexpensive "kit" style lenses compare with expensive ones, see our Ratings [link to lens ratings] of SLR lenses (for subscribers).

Even if you can afford one, a higher-priced, higher-quality lens might not always be your best choice. The most important consideration in choosing a lens is that its aperture, focal length, and other features match the type of shooting you intend to do.

For a good-quality standard zoom lens, expect to pay at least $300. If you want one with a wider aperture—i.e. a smaller f/stop number such as f/2.8, which lets in more light—you could pay two to three times that.
A quality wide-angle or telephoto zoom lens can range from expensive to extremely expensive, so expect to pay at least $600 for a decent wide or long zoom. Any lens with an aperture of f/2.8 or faster sells for $1,000 or more.

Because they don't offer the versatility of a zoom, fixed focal length lenses are much less expensive even when they offer a fast aperture well suited for taking portraits. Most point-and-shoot cameras can't replicate this effect because their sensors are very small—the bigger the sensor, the shallower the depth of field. A 50-mm lens with an f/1.4 aperture will sell for about $300. A 50-mm lens with an f/1.8 aperture sells for less than $100.

In addition to costing less than a zoom, a fixed-focal-length lens is usually sharper and brighter, with better contrast, and suffers from fewer defects, mainly because it's made with fewer glass elements.

All-purpose lens with a typical range of 18 to 55 mm.

This lens is less versatile than a zoom but usually has better optical quality and a smaller, lighter build.

Designed to get close to the action, for sports or nature. A popular telephoto zoom lens is 70 to 200 mm or higher.

Best for capturing landscapes or groups of people, with a typical focal range of 16 to 35 mm.

For photographing extreme close-ups of small objects such as insects and plant life. 50 mm and 100 mm are popular focal lengths for Macro lenses.

For capturing images with special looks for artistic purposes. Ultra-wide-angle "fish-eye" lenses are popular, as are "Lensbaby" selective-focus lenses that let you move the optics to produce creative effects.

These lenses provide perspective control in architectural and product photography.

Use these for portrait and beauty photography.

The aperture is the hole, or opening, in the lens that determines how much light is let through to the imaging sensor. The widest opening a lens is capable of determines its maximum aperture. Most professionals who shoot portraits, sports, or anything in low light without a flash are drawn to "fast," or wide, aperture lenses.

A wider aperture in a lens (a larger hole) is signified by a smaller f/stop number such as f/2.8 or f/1.4. A higher f/stop number, such as f/16 or f/22, produces a tiny hole or aperture. The reason they're known as "fast" apertures is that the wider the opening, the more light that can reach the sensor, allowing photographers to shoot at a faster shutter speed to freeze action and get non-blurry images even in low light.

For portrait photographers, a wider aperture creates a shallower depth-of-field, which means that only a small amount of the scene in the foreground is in focus. When taking pictures of people, this shallow depth-of-field is a good thing because it helps to draw attention to a face. When you set a lens to its widest aperture, you lose some sharpness. How much you lose depends on the quality of the lens.

If you're looking for a lens with a wide aperture-say, f/2.8-you'll notice that it's quite a bit more expensive than one with a smaller maximum aperture-f/3.5 or 3.8, for example. That's because those wider apertures require larger diameter lens elements, which makes them heavier and more expensive.

When using a lens with built-in image stabilization, you can shoot at a few shutter speeds slower than you would otherwise and still achieve a blur-free image. Though image stabilization can add considerable cost to a lens, we recommend it for most telephoto lenses because it will help keep your shots blur free. But bear in mind that an image stabilizer will make a lens darker. With better lenses, the benefits of stabilization outweigh the loss of light. With other lenses, they might not.

If you're shopping for a lens, you're likely to see the term listed as Image Stabilization (IS), Vibration Reduction (VR), or Vibration Compensation (VR), depending on the lens manufacturer. Lenses with built-in image stabilization are able to physically shift a glass element in the lens to compensate for shaky hands to reduce image blur. This is done in slightly different ways depending on the manufacturer, but typically involves a small gyroscopic sensor embedded in the lens that automatically detects hand movement and then adjusts the glass to keep the shot steady.

An alternative to image stabilized lenses is in-camera image stabilization, which automatically shifts the imaging sensor to compensate for handshake. Companies that employ sensor-based image stabilization in their cameras include Olympus, Sony, and Pentax. The effectiveness of sensor-based stabilization varies with the focal length of the lens. The longer the lens' focal length, the less effective the stabilization.

Some manufacturers sell what are known as "digital specific" or "digital lenses" that are designed to work better with the sensor in digital SLRs as opposed to traditional lenses that are optimized for film. There's some debate as to whether there's a real advantage to digital lenses in terms of image quality but one thing can be said for certain-they're smaller and lighter than traditional lenses. Digital lenses take advantage of the 1.3x2.0 smaller size caused by image sensors, giving you better focal range in a smaller package. Many digital lenses are also less expensive than traditional lenses because their smaller diameter means that they require less glass.

Digital lenses also provide better corner-to-corner sharpness in your photos because they're directly calibrated to the camera sensor, to direct the light on the edges of the sensor at an angle less steep than would be the case with film. Olympus was the pioneer in creating digital lenses but now most of the major manufacturers have a line of lenses designed specifically for digital sensors.

Digital lenses are made for digital cameras with smaller, APS-C, Four Thirds, or Micro Four Thirds sensor formats and will not function properly on DSLRs that use full-frame sensors, which require a larger diameter of the lens, causing corners of the image to be blocked out (this is called vignetting). They also will not work on some digital and film cameras. Micro Four Thirds is a new system created by Panasonic and Olympus to help produce smaller cameras. The system is slightly different from SLRs because it does not use mirror or pentaprism viewfinders on top of the camera--just an electronic shutter--which allows Micro Four Thirds models to be smaller.

Zoom lenses that let you take photos across a wide focal range such as 28 to 135mm are fairly typical. This gives you a lot of versatility when you shoot. On the down side, zoom lenses are usually more expensive than fixed focal length or "prime" lenses. They're also heavier.

While there's a definite appeal to being able to get closer to or farther back from your subject by just turning the zoom ring, you might also want to consider a place in your camera bag for a prime lens. As mentioned before in this guide, you can get a nice and light 50-mm f/1.8 lens for less than $100. Prime lenses also have a reputation for being better quality than zoom lenses and for producing sharper images. (This, of course, depends on which prime and which zoom lens you are comparing.)

Ultra zooms offer an extremely wide focal range of, for example, 18 to 200mm. This type of ultra zoom lens is great for vacations because it allows you to travel with just one lens to use under every shooting condition. Best of all is that ultra zooms are relatively inexpensive, selling for from $500 to 600 with built-in image stabilization.

There are some drawbacks to these light and economical lenses though. And when stacked up against images from a good prime lens, images captured with an ultra zoom typically don't look as crisp. Ultra zooms are also built mostly of plastic and so are less rugged and weather resistant.

The build quality of a lens is an important thing to consider if you plan to take photos in less than optimal conditions. High-end lenses are made of metal rather than plastic or polycarbonate, so there's some protection if you drop or bump them. The actual lens mount on a higher-priced lens is almost always made of metal while some cheaper lenses use a less sturdy plastic lens mount. They're also weatherized to prevent moisture from seeping in and resistant to dust and dirt. Some photographers also like the heavier weight of a high-quality rugged lens because it's easier to keep steady when you shoot. Most important: More-expensive lenses use better glass.

One of the largest camera and lens manufacturers in the world, Canon currently sells scores of lenses in a wide variety of focal lengths. Canon splits its lenses into two main classes—its standard EF (electro focus) series, and its consumer-level EF-S lenses, which are only compatible with its smaller, APS-C sensor bodies. There are also two smaller classes of Tilt-Shift (TSE) lenses and Macro (MP-E) lenses. More generally speaking, Canon splits its lenses into nine main categories: ultra-wide zoom; standard zoom, telephoto zoom, wide angle, standard and medium telephoto, telephoto, super telephoto, macro, and tilt-shift.

Carl Zeiss AG produces high-end lenses for rangefinders, SLRs and DSLRs. Zeiss sells several ZM-class lenses that are compatible with Leica M mount rangefinder cameras, and with its own Zeiss Ikon rangefinder camera. It also produces ZA-class lenses for Sony's Alpha line of DSLRs. Zeiss also has manual lenses for Nikon's F-mount cameras (ZF), Canon EOS EF mount cameras (ZE), Pentax's K mount cameras (ZK), and for the M42 lens mount used on Pentacon/Practica/Pentax screw-mount cameras (ZS). The company also makes 360-degree tilt-shift lenses Canon EF, Nikon F, and Sony Alpha A mounts.

Leica Camera is a manufacturer of film and digital rangefinder cameras, SLRs, and a digital SLR/medium format hybrid camera. Leica has about 30 high-end (read: expensive) lenses for M-series rangefinder cameras. These are split into four categories: wide angle, standard, telephoto, and Macro. The company also has about 36 lenses for its R9 film SLR, though that camera was recently discontinued. Leica produces four lenses for its new S2 DSLR/Medium-format camera.

Nikon is also a world leader in cameras and lenses. The company currently sells about dozens of auto-focus lenses and several manual focus lenses under the Nikkor brand. It splits its lenses between a standard F-Mount category and a smaller DX format class designed specifically for its small size sensor DX-format digital SLRs but can be used on full-size sensor bodies using the camera’s sensor crop settings. Nikkor auto-focus and manual-focus lenses cover a variety of focal lengths and price points and are divided into seven main categories: zoom, micro (aka macro), fisheye, wide angle, normal, telephoto, and PC, which is Nikon's tilt-shift category.

Until 2002, Olympus sold film-based, 35-mm SLR cameras under the Olympus OM system. The company currently sells digital SLRs, which use the Four Thirds sensor system, under its E-series line of DSLRs, and lenses under the Zuiko Digital label. It is also developing cameras and lenses using the new Micro Four Thirds system. Olympus currently has more than 20 Zuiko Digital lenses in varying focal lengths that it splits into three classes: super high grade, high grade, and standard. Old Olympus film-camera lenses can be used with the Four Thirds system using an adapter ring.

Panasonic is another well-known name in the consumer electronics industry that has been expanding rapidly into the world of digital cameras using interchangeable lenses. Currently a few lenses are being sold under the Leica brand for Panasonic's Four Thirds system Lumix digital SLRs. Those cameras can also use any other Four Thirds lenses, including the Zuiko Digital lenses produced by Olympus and several Four Thirds lenses manufactured by Sigma. There are also a few lenses for Panasonic's smaller Micro Four Thirds G-series digital cameras. Those are sold under the Lumix brand name.

There are currently more than 25 lenses in the Pentax line in five classes: DA Star (high-grade DSLR), DA (consumer DSLR), DA Limited (Prime) lenses, DFA (for digital SLRs but compatible with 35mm film cameras), and FA (designed for film SLRs but compatible with DSLRs). Pentax lenses are also compatible with Samsung's GX line of digital SLRs.

Sigma makes lenses for its own digital SLRs along with manufacturing lenses with mounts for Canon, Nikon, Sony, Pentax, and Panasonic (Four Thirds) cameras. The company has about 60 lenses in categories including wide zoom lenses, standard zoom, telephoto zoom, wide (fixed focal), standard (fixed focal), macro, DC (for DSLRs with APS-C sensors), and tele (telephoto) lenses.

Sony has only been in the DSLR game since 2006 but it has quickly become a major contender. Sony purchased DSLR technology from Konica Minolta in June 2006 and then produced its Alpha series of digital SLRs using some of Konica Minolta's camera innovations. Sony's Alpha cameras use the Konica Minolta lens mount and so are compatible with older Minolta auto focus lenses and Minolta lenses rebranded under the Sony name. Sony currently has more than 20 lenses in its stable, including several premium models that were developed for Sony by the German lens manufacturer Carl Zeiss. Other Sony categories for lenses are: zoom, fixed focal length, macro-STF-reflex-fisheye, and G lenses (professional).

Tamron currently manufacturers lenses with mounts for Canon, Nikon, Sony, and Pentax cameras. Sony is a major shareholder in Tamron. The company currently sells more than 20 lenses in four different classes: Di (digital integrated) lenses, Di II (for DSLRs with APS-C sized sensors only), SP (super performance, professional lenses), and conventional lenses. Tamron breaks its lenses down into four general categories: all-in-one zooms, fast zooms, wide and tele lenses, and macro lenses.

Tokina recently partnered with Pentax to develop lenses. Tokina also manufacturers lenses in the Nikon and Canon mounts.

It offers AT-X PRO series lenses that include wide-angle zooms, a telephoto zoom, and Macro lenses, all with apertures of either f/2.8 or f/4. They also offer two lenses in the consumer-level AT-X series, a wide-angle zoom and a telephoto zoom.

If you're interested in exploring photography more fully and are considering a digital SLR but haven't bought one yet, we recommend passing on the standard kit lens and buying the camera "body only." Then take the $100 or so you'll save and invest it in a better lens with a more rugged build and a wider aperture, which will help you to produce more professional-looking photos with a focal length that suits your photographic needs or style.

If you're interested in portrait photography and want to really make the person you're photographing stand out, you'll need either a standard zoom or a fixed prime lens with a fast aperture. A "fast" or wide aperture—such as f/2.8 or lower—produces good "bokeh," a Japanese word that loosely translates as that blur behind the subject that helps draw attention to the face.

The faster the aperture, the shallower the depth-of-field, which will produce more dramatic blur in your portraits. A good standard zoom range for a portrait lens would be 28 to 80 mm, though a lengthier zoom of 28 to 200 mm provides more compression in your shot for added blur. For a prime lens, we suggest a 50 mm or, even better, an 85-mm lens, so you can take a close-up (i.e. head and shoulders) of your subject without perspective distortion (i.e. the "dog nose" effect).

Because most digital SLRs act as though they magnify a lens' focal length, the 18-to-55-mm lens that comes with the camera might not be wide enough for landscapes, group shots, or travel photography, because it actually converts to about a 28-to-85-mm equivalent.

Camera companies have been producing wide-angle lenses that take into account this "magnification factor" of 1.3x or greater. Focal lengths of 10 to 22 mm and 12 to 24 mm on lenses designed specifically for digital SLRs are becoming increasingly popular because they convert to more traditional wide-angle zoom ratios of 15 to 33 mm and 18 to 36 mm equivalent.

Wide-angle lenses with a fixed focal length, such as a 12-mm lens, are also worth exploring because they're less expensive than zooms but will still help you to capture a scenic landscape such as an African savanna or Caribbean coastline and provide better optical quality.

These wide-angle lenses—zooms and primes—are also great if you're capturing group shots of friends and family, or if you're photographing a wedding and want to make sure that some of the cousins, aunts, and uncles don't get cut out of the group portrait.

When shooting a sporting event, you're going to need to get close to the action. The good thing is that telephoto lenses, which are designed to take close-up images of faraway subjects, have come down in price. So you can get a decent 70-to-200-mm zoom for $600 to $800. But because most fixed focal length "prime" telephoto lenses have fast apertures for professional photographers—a 300-mm f/2.8 is typical—they tend to be more expensive, selling for $1,000 and up. Also, prime telephoto lenses tend to be more expensive than telephoto zoom lenses because their apertures are usually wider, which requires more glass to manufacture.

To add some additional length to your telephoto, you should also consider a tele converter. A tele converter is a small lens that mounts behind a lens and increases its reach. A 2x tele extender doesn't cost a lot, $100 to $200, and will help you to double a lens' magnification. But it also makes the lens darker and slower, and it doesn’t change focal length or perspective.

Capturing images of nature close-up is one of the true joys of photography, which explains the abundance of affordable Macro lenses these days. A Macro is a lens that can focus extremely close to the subject and capture minute detail. Consequently, a macro lens is ideal for taking close-ups of small subjects such as flowers or insects. Typical Macro focal lengths include 60 mm, 100 mm, and 180 mm. They're often identified as a Macro in their model name.

Telephotos are also great for photographing nature, particularly large animals and other wildlife. Even better though are super telephotos, which range from 400 mm and up. Pop a 2x converter on one of those long lenses and you're ready for your next African safari. Be forewarned though—such a lens combo will cost you several thousand dollars, so consider renting one if it's just for a day trip.

If you can't afford a pricey telephoto for your next safari and don’t want to rent one, there are some decent, low-priced zoom lenses out there that go as long as 300 mm. Add in the 1.6x magnification factor for consumer DSLR that we mentioned earlier, and your 300-mm lens becomes a 480-mm equivalent.

If you want to get really creative, consider a specialty lens that can turn a seemingly ordinary scene into a work of art. If you like wide-angle photos, you'll love fisheye lenses that use radically curved optics to capture 180-degree scenes. Fisheyes come in a variety of focal lengths but 15 mm or 16 mm are typical. They're great for when you want to capture absolutely everything in a scene, or when you want to produce a surreal-looking, curved effect for a close-up or a landscape.

Tilt-shift lenses, which allow you to control the perspective in your image by tilting and shifting the lens in front of the sensor, have become increasingly popular for their distinctive photographic effects. When used properly, a tilt-shift lens can produce extremely shallow depth-of-field, creating a "miniature" effect on your subject. This is particularly true when shooting large scenes of people, cars, or boats from above. Tilt-shift lenses tend to be very expensive though—$1,000 and higher. As an alternative, you might want to try a Lensbaby selective focus lens, which sells for $100 to $150. Lensbabies combine a basic lens with a built-in bellows that lets you twist and turn the optics to selectively focus parts of a scene. The effect can be dreamy or slightly surreal, with a small "sweet spot" of focus in the image and the rest blurred.

The biggest trend in interchangeable lenses is to offer a very wide zoom range (we've seen up to 18 to 270 mm) with built-in image stabilization for a reasonable price. While these lenses are great for vacations because they let you bring just one lens with you when you travel, there are some limitations. They're built mostly of plastic, so are less rugged and weather resistant than more expensive models. Though it might be more expensive and more cumbersome to use two or even three great lenses instead of just one good one, it's the image quality that counts most.

Though buying a good camera is important, you'd be amazed at how much better your photos look when they're shot with a high-quality lens. The problem is, it's not fiscally prudent to just buy a pricey pro lens on a whim. If you have a friend who is serious about photography or a "professional," see if you can try out his or her lenses to get an idea of which ones might give you the look you want. Once you try a high-end lens though, you might never want to go back to a consumer-level lens again.

Though buying online might give you a good deal, we recommend handling a lens in a store before you purchase it so that you can judge the weight and the ease of use. Because a good-quality lens is expensive—it can cost more than the camera—it's not a purchase that should be taken lightly. Look, and try, before you leap.

Though the obvious impulse is to buy a lens that matches the brand of your camera—Nikkor lens with Nikon cameras, Canon with Canon etc.—you can save a lot of money by considering a lens from a third-party manufacturer such as Tamron, Sigma, or Tokina. Though third-party brands are not as well known as the leading brands, the quality is excellent and you will save several hundred dollars.

If you want to add some "throw" to your telephoto lens, consider purchasing a tele converter (also known as a tele extender), which is a small lens that mounts behind a lens and increases its reach. A 2x tele extender doesn't cost a lot—$100 to $200—and will help you to double a lens' magnification. It's important to note that a tele converter will result in a decrease of the aperture on your lens from one to two f/stops.

Nothing beats a pro lens but for most consumers it's just too expensive. If you covet the lenses you see the pros using on the sidelines of the big game but can't afford them, bargains are to be had on eBay. Of course, before you buy anything on eBay check the seller's ratings first. If they are anything less than 98 percent positive, forget it. Also note the number of ratings a seller has and what types of sales they've made. If they've done a healthy amount of business selling photo gear without complaint, they're probably okay.

It's still a little-known fact, but most new digital SLRs are compatible with older, same-brand lenses for film cameras. Though new lenses, especially those that are optimized for digital cameras, are great, you might be able to fill out your camera bag with some of the lenses you used with your old Nikon or Canon SLR. (But be sure and dust them off first!) And attention former Minolta users: most of your old Minolta Maxxum auto-focus glass will work with Sony's new line of Alpha DSLRs.

When shopping for a new lens, you might see the same lens offered in two different places for very different prices. Oftentimes, the lower priced lens is actually a "gray market" model. A gray-market product is one that is not bought or sold through traditional distribution channels and thus can be offered for a far lower price. (Typically, they're imported from overseas.)

The big caveat to gray-market items is that they're often not covered by warranties. With something as expensive and delicate as a lens, having a warranty is worth the extra cost. It's also important to note that gray-market lenses are not eligible for the frequent rebates offered by the major lens manufacturers.

A final word: The lens is the component that most influences the quality of your images. A good lens is a long-term investment that might outlast several camera bodies and last many years.