Monday, March 15, 2010
Five Myths About Lenses—03/15/10
Fighting fiction with facts to make you a better photographer
MYTH 1: Prime lenses always are better than zooms. Not true. Several years ago it was much harder to make really sharp zoom lenses that could compete optically with prime (fixed focal length) lenses. Today, though, not only have advances in lenses, coatings, engineering and construction made zoom lenses optically phenomenal, they’ve been engineered to do things no prime lens can. Most notably, zooms can accommodate a wide range of focal length in a single body. There’s proof right there that primes are not always better than zooms.
MYTH 2: Zoom lenses always are better than primes. I know, it doesn’t make much sense that this, too, is a lens misconception. But there tends to be a prevailing wisdom that the seemingly infinite range of focal lengths available in a zoom lens makes it innately superior to a prime. Apparently if your composition isn’t perfect it’s best to simply zoom in or out to fix the framing. The problem with that approach, though, is that it can make you a lazy photographer—not only physically, but creatively too. One of the best ways to hone your critical seeing skills is to take one lens, a fixed focal length, and push yourself to make interesting pictures with it. You’ll have to shoot close-ups and wide angles, change perspectives from high to low, and generally work a little harder to make great pictures. And you know what? You will.
MYTH 3: You should always protect your lenses with a filter. This one’s true, except when it’s not. Why would you ever spend $1,500 on a new lens and immediately cover it with a $10 piece of plastic UV protection? If you’re going to do that, you might as well invest in 15 $100 lenses and skip the big investment in the first place. The truth is that protecting the lens with a filter can be great advice, but only if you don’t compromise the optical quality of your quality lenses. If you do, you have to ask yourself if it’s really worth protecting your equipment at the cost of lesser pictures with every exposure. I say it’s not.
MYTH 4: The speed of a lens refers to how fast that lens can autofocus. False! This one isn’t so much a myth as an easy mistake to make. And it’s just plain wrong. The speed of a lens refers to how much light it allows in—meaning how large of a maximum aperture it has. More light means faster shutter speeds, making it a faster lens. An ƒ/2 lens, for example, is one stop “faster” than an ƒ/2.8. An ƒ/1.4 lens is a half-stop faster than an ƒ/1.8 lens, and so on. If you want a fast lens, that means you want a lens that opens wide to allow a lot of light, making it easier not only to use faster shutter speeds but to work in lower light.
MYTH 5: Fast fixed-maximum-aperture lenses always are better than variable maximum apertures. This one also sounds like a plausible myth, but it’s just not true. When you get below the surface and think about what those variable maximum apertures actually accomplish, you realize there are many benefits. Sure, fast lenses are desirable because they make it easier to work with faster shutter speeds and in lower light. But in other situations, or for photographers who prefer to work at smaller apertures and longer shutter speeds, a variable maximum aperture might never come into play. Better yet, the ability for a zoom lens to adjust its maximum aperture makes for lenses with greater focal ranges and smaller, lighter lenses. That’s a significant benefit for photographers who like to travel light, or those who want to get a wide variety of focal lengths from a single, portable lens.
BONUS MYTH 6: You only need a lens shade when shooting into the sun. There’s so much wrong with this myth I almost don’t know where to begin. Suffice it to say that lens flare is a real photo killer. Besides those dramatic and obvious optical aberrations that come from the worst examples of flare, the stuff can ruin pictures in subtle ways, too. Reducing contrast or creating general color casts in an otherwise correctly exposed image, lens flare will strike when you least expect it. Any time a light source, even one that isn’t a bright, hard light like the noonday sun, is shining on your lens, you’re bound to suffer the effects of flare. The best way to fight flare is to keep those lights from hitting the front element of the lens, and one of the best ways to do that is the simple use of a lens shade. Your photos—particularly their contrast and color rendition—will thank you.