Monday, December 26, 2011
Myths About Zoom Lenses—12/26/11
These versatile lenses are sometimes misunderstood
|This Article Features Photo Zoom|
— Myth 1: Zoom lenses aren't as sharp as primes. This one probably had a grain of truth at one point, but that point was decades ago. Back in the day a zoom lens had to be filled with multiple elements, and those elements weren't nearly as refined as they are today. With advances in lens-making techniques, lens makers have refined the quality of zooms—from sharpness to chromatic aberrations—to the point that a top-quality zoom can be as sharp as the best primes. I bet most of today's zooms are sharper than the run-of-the-mill prime lenses from back in the day when this rumor got its start.
— Myth 2: Zoom lenses are heavy. Sure, okay, fine. A zoom lens—particularly a large one with a wide focal range and large maximum aperture—can be a bit hefty. But then again, you can use a single zoom lens (say, a 24-105) to replace a wide angle, a normal and a telephoto. That's three lenses for the price—and weight—of one. So remember, when you're sacrificing space in your bag for a big zoom lens, you're probably taking two or three lenses out in its place.
— Myth 4: Cropping is the same as zooming in. You think don't need a long zoom lens because cropping into a high-res image is the same as zooming in closer? Or you think you can get away with a shorter lens on a sub-full-frame D-SLR sensor because it's basically the same thing? Think again. One thing cropping can't achieve is a zoom lens' ability to compress a scene. There's a unique perspective to a longer lens, and cropping into a wide-angle view just doesn't look the same. And if you're not zooming in close it's much harder to focus precisely. There's room for this error in wide views, but not once you crop in close. And it's commonly understood that longer lenses have shallower depth of field (which may technically be a an issue of scene compression enlarging out of focus areas of a scene) that can't be recreated in cropping. The point is this: cropping your wide-angle shots just won't look the same as shooting with your telephoto zooms.