Tuesday, December 1, 2009
Choose Your Perfect Zoom
The modern zoom lens is a marvel of technology, and it’s the nature photographer’s best friend
Manufacturers often offer a zoom range in two versions: faster and slower. For example, Canon offers 70-200mm zooms in ƒ/2.8 and ƒ/4 flavors. The former admits more light, so is better for dim-light shooting, as it allows for a faster shutter speed, offers a brighter viewfinder image and provides quicker autofocusing—and costs a lot more. The ƒ/4 is more compact and lighter, costs less and still performs very well—a great choice when you want to travel light or have a limited budget. Since many AF SLRs can’t autofocus with lenses slower than ƒ/5.6, the ƒ/2.8 lens offers another advantage: You can attach a 2x teleconverter, and the resulting 140-400mm ƒ/5.6 combo will still autofocus (albeit somewhat more slowly than the lens alone). With the 70-200mm ƒ/4 and a 2x converter, you’ll be focusing the resulting dim ƒ/8 image manually.
Fixed-aperture zooms maintain their maximum aperture throughout their zoom range: A 70-200mm ƒ/2.8 has a maximum aperture of ƒ/2.8 at all focal lengths. Many zooms have variable maximum apertures: Sigma’s 150-500mm ƒ/5-6.3, for example, has a maximum aperture of ƒ/5 at 150mm and a maximum aperture of ƒ/6.3 at 500mm. Through-the-lens metering in digital and 35mm SLRs automatically compensates for this, but you’ll have to keep it in mind if using a handheld meter.
Most zoom lenses today provide two rings, one for focusing and one for zooming. Some use a single ring; rotating it focuses, and pushing it away from the camera body or pulling it toward the camera body does the zooming. Some photographers (myself included) prefer the two-ring design; others prefer push-pull. Before buying a zoom lens, try it out and see how you like its zoom control.
You have to consider your camera’s format (sensor size) when choosing a lens for a specific task. A focal length that provides a moderately wide angle of view when used on a 35mm or full-frame digital SLR becomes a “normal” lens when used on an APS-C digital SLR because the latter’s smaller sensor “sees” less of the image the lens produces.
Wide-angle zooms are those that start at a wide-angle focal length for the camera format. Popular wide-angle zooms among APS-C-format landscape shooters include Canon’s EF-S 10-22mm ƒ/3.5-4.5 USM, Nikon’s AF-S DX Zoom-Nikkor 12-24mm ƒ/4G, Pentax’s DA 12-24mm ƒ/4.0, Sigma’s 10-20mm ƒ/3.5 EX DC HSM, Sony’s DT 11-18mm ƒ/4.5-5.6, Tamron’s SP AF10-24mm F/3.5-4.5 Di II and Tokina’s 11-16mm ƒ/2.8 AT-X PRO DX. For Four Thirds System users, the Olympus Zuiko Digital 7-14mm ƒ/4.0 provides the widest views.
Popular with the full-frame and 35mm set are Canon’s EF 16-35mm ƒ/2.8L II USM, Nikon’s AF-S Nikkor 14-24mm ƒ/2.8G, Sigma’s 12-24mm ƒ/4.5-5.6 EX DG HSM, Sony’s Zeiss 16-35mm ƒ/2.8 and Tamron’s SP AF17-35mm F/2.8-4 Di.
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