Not every subject lends itself to the ultrawide perspective, of course. With the Sigma 10-20mm at 20mm, this photo has more depth than if it had been photographed with a normal or telephoto lens (which would have created some foreshortening), but it has very little wide-angle distortion. Keeping the camera level also minimizes any distortion.
Wide-angle zooms have always been popular with nature photographers. When you venture into the ultrawide arena, a new world of opportunities opens up. Ultrawide zooms typically span the 15-35mm range, meaning they can go from very wide to a slightly wide-of-normal perspective. That's a lot of versatility in one lens. In this article, we're using the Sigma 10-20mm F4-5.6 EX DC to show some of the compositional options in this range. The Sigma lens is designed for APS-C DSLRs. These cameras have a magnification factor of 1.5x or 1.6x, depending on the manufacturer, which gives the Sigma 10-20mm an apparent field of view that's similar to a 15-16mm to 30-32mm lens on a full-frame DSLR. That translates to a range that's ultrawide to slightly wide. When you get wider than this range, you're usually entering into the realm of fisheye lenses, which usually exhibit extreme distortion.
At the wide end, the Sigma 10-20mm can get to 9.4 inches from the subject, which gives you some nice compositional options. Too many nature photographers think of the wide-angle lens as a good way to capture a wide angle of view. It's when you start to get close in at that wide angle that photos can become much more dynamic.
In this sequence, we show an unremarkable landscape scene. The first image does a fine job of capturing the vista. The bush in the center of the photo is somewhat more interesting than the overall scene. Moving closer and shifting from the 20mm end of the range to 10mm, we hone in on this feature as the main subject. The ultrawide distortion gives the subject dimension and depth. Of course, as you get closer, even with a very wide-angle perspective, you still have to be careful to have sufficient depth of field. It's easy to get complacent because you can carry a lot of depth of field at a reasonably wide aperture, but when your subject is close to the lens, you have to pay attention.
Shooting a backlit scene at a wide angle helps you keep the sun very small. Here, the spindly shape of a scrub oak in Southern California's Malibu Canyon is on display from top to bottom. The lens was set at 16mm, and the camera was positioned so that the sun barely peeked out from behind a branch. Getting in close and aiming the camera created the arching effect of the branches and foliage at the top of the frame.