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Outdoor photographers have long sought the “do-it-all” lens, a single unit that could handle everything from wide-angle to telephoto and close-ups. Camera and independent lens manufacturers have responded to our needs with superzooms designed specifically for DSLRs with APS-C and Four Thirds image sensors by making a number of 10x-plus zooms that are ideal for traveling light and give you lots of options for framing anything from a travel scene to a bird in flight to a majestic landscape. Today, the range includes 18-200s, 18-250mm and even an 18-270mm (which, despite its amazing 15x zoom range, measures just 3.1x3.9 inches at the wide-angle setting and weighs under 20 ounces—remarkable considering it provides 35mm-camera-equivalent focal lengths from 27-405mm!). These super-range superzooms even focus down to under 20 inches. And did we mention that the superzooms give you all those focal lengths in that compact package for well under $1,000?
Yes, the superzooms are versatile, easy to carry and affordable. So what’s the catch?
Benefits And Drawbacks
Superzooms by their very nature require a series of design compromises. It’s difficult enough to correct a prime (fixed-focal-length) lens to be sharp and aberration- and distortion-free at its single focal length. With a zoom, designers have to correct for aberrations and distortion at a wide range of focal lengths, and correcting an aberration at one focal length can make that aberration or another one worse at another focal length. Today’s designers use high-tech materials, aspherical and extra-low-dispersion elements, and computer-aided design to produce amazingly good performance throughout a very wide focal-length range.
|The 10x designed-for-digital superzooms can be a one-lens solution for many nature photographers. Long favored for travel photography, today’s lenses also can be used for landscapes, macro and even wildlife.|
Still, the superzooms don’t produce quite the image quality of top prime (single-focal-length) lenses of equivalent focal length—a given manufacturer’s 28mm wide-angle lens will produce sharper images with less distortion and vignetting than the same manufacturer’s 18-200mm zoom at 28mm, and the manufacturer’s 200mm prime telephoto lens will produce better image quality than its 18-200mm superzoom at 200mm. But each prime lens can cost more than the superzoom, and you only get the single focal length. It’s a trade-off, and many find the cost and convenience of the superzoom more than offset the slight loss of image quality.
Superzooms are also slower than primes. Most wide-angle primes have a maximum aperture of ƒ/2.8 or faster, as do most 200mm telephoto lenses, while most superzooms have a maximum aperture of ƒ/3.5 at the wide end and ƒ/5.6 or ƒ/6.3 at the long end. This means you’ll be better off with primes if you specialize in handheld low-light photography or like to do selective-focus work at wide apertures.
But superzooms remain popular. Besides convenience, space and cost savings and ease of travel, superzooms offer a couple of other advantages over prime lenses. For one thing, they help keep your sensor free of dust because you won’t have to change lenses nearly as often as when using primes. For another, you can set intermediate focal lengths. Even if you have a whole complement of prime lenses on hand, the ideal focal length for a particular shot might be between them. And being able to change to any of the focal lengths with a quick twist of a wrist will help you fine-tune compositions and capture those decisive moments you’d miss if you had to change lenses as the moment happens.
Most superzooms are varifocal lenses, which don’t maintain focus as they’re zoomed. This usually isn’t a problem when autofocusing, as the AF system automatically handles it, but it’s something to keep in mind if you focus manually. With a true zoom, you can focus manually at the longest focal length for a magnified view of the subject, then zoom out to the desired wider view for the shot. With a varifocal lens, you can’t because focus will change as you zoom out; you’ll have to focus at the desired focal length for the shot.
Another superzoom variable is the maximum aperture. As mentioned, a typical 18-200mm lens has a maximum aperture of ƒ/3.5 at the widest focal length and a maximum aperture of ƒ/6.3 at the longest. (These carry through the aperture range; stopped all the way down, the 18-200mm ƒ/3.5-6.3 zoom has an aperture of ƒ/22 at 28mm and ƒ/40 at 200mm.) Through-the-lens metering automatically handles this, but you’ll have to keep it in mind if setting exposures manually via a handheld meter or the Sunny 16 rule.
Yet another variable is the fact that with most superzooms, the focal length decreases as you focus closer, such that at the minimum focusing distance, the 200mm setting may really be only 140mm or so. This means you don’t get the magnification you’d expect from a 200mm lens focused at 17.7 inches. Some people get upset when they learn this, but it’s not that big a deal. First, no 200mm prime lens (except a true macro one) can focus anywhere near 17.7 inches; most can’t focus closer than five feet (60 inches—three times farther away). Second, the superzooms still give you considerably bigger images of flowers and bugs in your close-ups than a 200mm prime lens can—140mm at 17.7 inches produces more magnification than 200mm at 60 inches. Bottom line: Most 18-200mm superzooms will get you close enough to produce an image one-quarter life-size at the film plane, while most 200mm prime lenses (true macro lenses excepted) will only take you down to around one-sixth life-size.
Internal Focusing. All the 10x-plus superzooms feature internal focusing. This means elements inside the lens are shifted to adjust focus, rather than physically extending the lens to adjust focus. Advantages of internal focusing are many. Since fewer and smaller elements have to be moved, autofocusing is quicker. The physical length of the lens doesn’t change during focusing, so balance is better. The front element doesn’t rotate during focusing, so orientation-sensitive lens attachments like polarizers and graduated filters retain their orientation during focusing. Internal focusing also allows for much closer minimum focusing distances (although the focal length often decreases somewhat at the closest focusing distances), generally providing reproduction ratios of around one-quarter life-size at the longest focal-length setting, great for flower close-ups. (Note that while the lens doesn’t change physical length during focusing, superzooms do increase in physical length when zoomed to their longest focal lengths.)
Stabilization. Many superzooms feature built-in image stabilization (Canon’s pioneering stabilization is called IS, for Image Stabilizer; Nikon’s is VR, for Vibration Reduction; Sigma’s is OS, for Optical Stabilizer; and Tamron’s is VC, for Vibration Compensation). With these lenses, a group of elements is shifted to counter handheld camera shake, and this is a terrific feature if you shoot handheld, especially at longer focal lengths or in dim light. Bear in mind that stabilization will compensate for camera movement, but not subject movement—moving subjects will come out blurred at slower shutter speeds unless you pan the camera to track their motion. Olympus, Pentax and Sony offer DSLRs with built-in sensor-shift stabilization, which moves the sensor itself instead of lens elements to counter camera shake. This has the advantage of working with any lens you attach to the camera and the drawback of stabilizing only the recorded image, not what you see in the viewfinder. If you use a stabilized superzoom with an Olympus, a Pentax or a Sony body that has sensor-shift stabilization, switch off either the lens or body stabilizer—don’t use both stabilizers simultaneously.
Special Elements. Wide-angle lenses tend to suffer from barrel distortion, spherical aberration and chromatic aberration. Long lenses tend to suffer from pincushion distortion and various aberrations. Correcting these with standard lens elements is difficult, if not impossible, even for a single focal length. So lens manufacturers use special elements in combinations to correct them amazingly well. ED, LD and SLD elements have unusually low dispersion characteristics, minimizing chromatic aberrations. Aspherical elements help focus light rays from the edges of the lens at the same plane as light rays coming in through the middle. These and other exotic elements allow designers to produce lenses that perform well through a wide range of focal lengths, are remarkably compact, focus amazingly close and cost surprisingly little. All superzooms employ a number of these special elements.
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Special Focusing Motors. Some superzooms incorporate special ultrasonic focusing motors that provide quicker and quieter operation. Nikon’s 18-200s use Nikon’s AF-S Silent Wave focusing motor, and Sigma’s 18-200mm and 18-250mm HSM lenses incorporate Sigma’s Hyper Sonic focusing motors. Ironically, Canon, whose USM was the first such motor, doesn’t include it in its EF-S 18-200mm superzoom. Olympus and Tamron also produce lenses with such focusing motors (SWD and USD, respectively), but neither uses them in their superzooms at this time.
For this article, we’ve chosen to highlight models with 10x or greater range. We feel this is what defines the term “do-it-all superzoom.”
EF-S 18-200mm ƒ/3.5-5.6 IS ($699 MSRP)
Introduced in Fall 2008, the EF-S 18-200mm ƒ/3.5-5.6 IS superzoom was designed specifically for Canon’s APS-C-format DSLRs (except the old 10D and earlier models, on which it can’t be mounted). Among its 16 elements (in 12 groups) are two UD and two high-precision glass mold aspherical elements to control chromatic and spherical aberrations, along with a configuration and coatings designed to minimize flaring and ghosting and yield excellent color balance. The Image Stabilizer (IS) system is said to be good for four shutter speeds—if you can get sharp handheld shots at 1⁄320 sec. at the 200mm setting without stabilization, you should be able to get sharp handheld shots at 200mm at 1⁄125 sec. with the IS switched on. The lens features a handy zoom lock to keep the lens from extending as you carry the camera. The zoom ring is much wider than the focusing ring and toward the rear of the lens, with the narrow focusing ring at the front, so you aren’t likely to mistake one for the other in use.
Contact: Canon, www.usa.canon.com.
AF-S DX Nikkor 18-200mm ƒ/3.5-5.6G ED VR II ($849 MSRP)
AF-S DX VR Zoom-Nikkor 18-200mm ƒ/3.5-5.6G IF-ED ($784 MSRP)
Nikon introduced its first 18-200mm superzoom late in 2005, the AF-S DX VR Zoom-Nikkor 18-200mm ƒ/3.5-5.6G IF-ED. Designed specifically for the DX (APS-C) format, it features Nikon’s VR II second-generation vibration-reduction system, said to be good for up to four stops (if you can get sharp handheld shots with an unstabilized 200mm lens at 1⁄320 sec., VR II theoretically allows you to do it four shutter speeds slower: 1⁄20 sec.). Nikon’s Super Integrated Coating (SIC) reduces ghosting and flare. Two ED elements and three aspherical elements minimize chromatic aberrations and distortion, while a Silent Wave Motor provides quick and quiet autofocusing. The AF-S DX Nikkor 18-200mm ƒ/3.5-5.6G ED VR II superzoom introduced in mid-2009 offers the same features and 16 element/12 group construction, but adds a useful zoom lock to keep the lens from extending as you carry the camera. (On the newer lens, the VR logo is in gold; on the earlier version, it’s in red.)
Contact: Nikon, www.nikonusa.com.
Zuiko Digital ED 18-180mm ƒ/3.5-6.3 ($499 MSRP)
Equivalent to a 36-360mm zoom on a 35mm camera, the Zuiko Digital ED 18-180mm ƒ/3.5-6.3 superzoom can be used on all Four Thirds
System cameras (and, via adapter, on Micro Four Thirds System cameras, too), not just those from Olympus. At its minimum focusing distance of 17.6 inches, it produces a magnification of 0.23x at the image plane, but the Four Thirds format’s 2x “crop” factor means a given subject will fill as much of the frame as at a 0.46x magnification with a 35mm camera. Two ED and two aspherical elements compensate for aberrations throughout the focal-length range.
Contact: Olympus America, www.getolympus.com.
18-200mm ƒ/3.5-6.3 DC ($510 MSRP)
18-200mm ƒ/3.5-6.3 DC OS HSM ($690 MSRP)
18-250mm ƒ/3.5-6.3 DC OS HSM ($800 MSRP)
Sigma offers three designed-for-digital superzooms. All will focus down to 17.7 inches at all focal lengths. The two OS lenses come with Sigma’s Optical Stabilizer, which automatically adjusts a lens group to compensate for handheld camera shake, and Sigma’s HSM Hyper Sonic focusing motor, which provides quick and quiet autofocusing. All three feature inner focusing, aspherical and SLD (Super Low Dispersion) elements to correct aberrations and distortion, and handy zoom locks. All are available in mounts for Sigma, Canon and Nikon DSLRs; the non-OS 18-200mm and the 18-250mm are also available in mounts for Pentax and Sony/Minolta DSLRs. Nikon-mount versions have built-in AF motors so they autofocus with the Nikon bodies that lack one (D40, D60, D3000, D5000).
Contact: Sigma, www.sigmaphoto.com.
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DT 18-200mm ƒ/3.5-6.3 (Model name = SAL 18200) ($529 MSRP)
DT 18-250mm ƒ/3.5-6.3 (Model name = SAL 18250) ($579 MSRP)
Sony offers two superzooms designed specifically for their APS-C-format DSLRs. When attached to Alpha full-frame cameras, the image size is automatically adjusted to 11 megapixels, so there’s no vignetting in the recorded image. The optical viewfinder is equipped with indicators to identify the corners of the cropped frame, and the view will show vignetting. The DT 18-200mm ƒ/3.5-6.3 features 15 elements in 13 groups, including two ED and three aspherical elements to counter aberrations and distortion. It measures a compact 2.9x3.4 inches and weighs just 14 ounces. The DT 18-250mm ƒ/3.5-6.3 adds 25% to the long end, yet has the same compact measurements and weighs just 15.5 ounces. The SAL18250 has two aspheric elements (instead of the three used in the SAL 18200), and is 2mm wider in diameter. These lenses also can be used on old Minolta DSLRs.
Contact: Sony, www.sonystyle.com.
AF18-200mm F/3.5-6.3 XR Di II LD Aspherical (IF) Macro ($299 MSRP)
AF18-250mm F/3.5-6.3 Di II LD Aspherical (IF) Macro ($499 MSRP)
AF18-270mm F/3.5-6.3 Di II VC LD Aspherical (IF) Macro ($629 MSRP)
Tamron’s designed-for-digital superzoom trio includes 18-200mm, 18-250mm and 18-270mm models, the last being the widest-range zoom available for DSLRs at 15x. All were designed specifically for the APS-C format, and all feature LD (low dispersion) and aspherical elements to minimize aberrations and distortion, plus internal focusing. The 18-200mm lens also employs Tamron’s XR (extra-low refractive index) glass, which can bend light at steeper angles and helps decrease lens length and diameter while minimizing aberrations. The AF18-270mm VC is available for Canon and Nikon. The AF18-200mm and the AF18-250mm are available in mounts for Canon, Nikon, Pentax and Sony DSLRs; the Nikon versions include a built-in focusing motor, so will autofocus with the Nikon bodies that lack one. All three Tamron Di II superzooms have handy zoom locks.
Contact: Tamron, www.tamron.com.
AT-X 16.5-135mm ƒ/3.5-5.6 DX ($499 MSRP)
Tokina produced a 35-200mm superzoom back in 1982, but today its widest-range zoom is the AT-X 16.5-135mm ƒ/3.5-5.6 DX. While this falls a bit short of our 10x benchmark, it provides a versatile 25.5-202.5mm-equivalent range when used on the APS-C DSLRs for which it was designed and gives a little more punch on the wide end than the 18-XXX zooms. SD and aspherical elements minimize chromatic aberration and distortion and maximize contrast. There’s no zoom lock, but a high-precision mechanical zoom cam system minimizes end play and zoom creep—handy when shooting upward or downward (where a zoom lock wouldn’t help, anyway, since it just locks the lens at its shortest focal length for travel). The AT-X 16.5-135mm is available in Canon and Nikon mounts (the Nikon version does not contain an AF motor, so the lens won’t autofocus with Nikon bodies that lack one—the D40, D60, D3000 and D5000).
Contact: Tokina (THK Photo), www.thkphoto.com.
Lumix G Vario HD 14-140mm ƒ/4.0-5.8 ASPH MEGA O.I.S. ($849 MSRP)
Okay, it’s not really a DSLR lens. It’s sold with the Lumix DMC-GH1, which looks like a DSLR, but isn’t. But the Lumix G Vario HD 14-140mm ƒ/4.0-5.8 is a 10x superzoom, and it has a unique twist: It’s designed for video shooting with video-capable cameras like the GH1. The lens has a continuous aperture and a silent AF motor, so operating sounds aren’t picked up by the camera’s built-in microphone. It provides smooth, continuous contrast-based autofocusing for both still images and video clips. The 14-140mm contains 17 elements in 13 groups, including two ED elements and four aspherical ones, and can focus down to 19.7 inches. It even has Panasonic’s built-in MEGA O.I.S. optical image stabilizer to counter handheld camera shake. Like all Micro Four Thirds System lenses, the Lumix G Vario HD 14-140mm can be used with any Micro Four Thirds System camera and with standard Four Thirds System cameras using the DMW-MA1 lens mount adapter.
Contact: Panasonic, www2.panasonic.com.
Designed For Digital
For years, camera and lens manufacturers designed lenses for 35mm cameras. When digital imaging developed, most 35mm SLR manufacturers produced digital SLRs by adapting their 35mm bodies. This offered a number of benefits, including cost savings, familiar bodies for current SLR users and a wide range of existing lenses. Digital sensors require light to strike them at a more direct angle than 35mm film so results weren’t always optimal when lenses designed for 35mm film were used for digital imaging.
The Four Thirds System was introduced in 2003 (in the Olympus E-1) to eliminate this problem. Instead of adapting existing 35mm SLR bodies to digital imaging, Olympus started from scratch and designed a DSLR to be digital from the outset. The sensor size, lens-mount diameter and lenses were all designed with digital imaging in mind. The lenses send light to the pixels at a more direct angle, enhancing performance.
Non-Four Thirds manufacturers soon introduced lenses designed specifically for their APS-C image sensors (which, at around 23.6x15.8mm, are considerably smaller than 36x24mm “full-frame” 35mm film and sensors, but larger than 17.3x13.0mm Four Thirds sensors). This improved performance and reduced lens size, since the lenses didn’t have to cover the 43.2mm image circle required by 35mm film (and full-frame image sensors). Note that the higher-end APS-C lenses provide excellent performance, while the low-priced “kit” lenses are aimed more at the budget-minded user.
Along with lenses designed specifically for the smaller image sensors, the film-camera companies and independent lens makers also have been upgrading their full-frame lenses by improving the antireflection coatings and internal light baffling (digital sensors are much “shinier” than film, and poorly coated lenses can cause reflections and flare to appear in digital images).
Note that lenses designed for APS-C sensors generally can’t be used on DSLRs with larger sensors—vignetting would result, and in some cases, the rear lens element would interfere with SLR mirror operation. However, when a Nikon DX lens is attached to a Nikon full-frame DSLR, the camera automatically switches to cropped DX mode (DX lenses shouldn’t be attached to 35mm Nikon film SLRs, however). Canon’s EF-S lenses can’t be mounted on larger-sensor Canon DSLRs, and Sony’s DT lenses can be mounted on Sony’s full-frame DSLRs, but vignetting will occur.
Testing Your Superzoom
Each superzoom has one or more “sweet spots,” combinations of focal length and aperture where it produces its best image quality. Each also has one or more “sour spots,” combinations of focal length and aperture where it doesn’t perform so well. So it’s a good idea to test your superzoom at each of its marked focal lengths and each of its apertures to find out where these spots are for your specific lens. See the article on testing lenses in this issue, “The Certainty Of Sharpness,” for details on how to do it. It’s nice to know what to expect with your lens, so you can work around sour spots and favor sweet spots when possible.