|This Article Features Photo Zoom|
|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.
|This Article Features Photo Zoom|
Sigma 10-20mm F4-5.6 EX DC
We used the Sigma 10-20mm F4-5.6 EX DC lens for this article. An extremely versatile optic, it's designed for use on DSLRs with APS-C image sensors. With an angle of view of 102.4º at 10mm and 63.8º at 20mm, it's characterized as an ultrawide-angle to slight wide-angle zoom, which means that it can be used to create dramatic wide-angle distortion or almost none at all. The minimum focus distance of 9.4 inches allows you to get up close to a subject if you want to experiment with dramatic close-up effects. The lens features aspherical elements for improved performance and sharpness; it's internally focusing so it doesn't change dimensions as you focus, and it has the Sigma EX finish, denoting "superior build and optical quality." It takes a 77mm filter, and it weighs 16.4 ounces. The lens is available for Sigma, Nikon, Canon, Sony, Pentax and Four Thirds cameras (HSM is unavailable in Sony and Pentax mounts). Estimated Street Price: $429.
Contact: Sigma, www.sigmaphoto.com.
Backlight and sidelight almost always make dull foliage come to life. Think about photos of aspen leaves at the height of fall color. When backlit, their yellow leaves are alive with luminosity. Even less dramatic subjects can benefit from backlight and sidelight. Taking advantage of the 10mm end of the Sigma's focal range, this scene has depth, and the main subject is transformed from mundane to an interesting study in shape and light. Unfortunately, the shot is ruined by the annoying flare at the bottom of the frame. When you're shooting at a very wide angle, it's easy to get a bad flare like this one when the sun is just out of the frame. A lens shade can help, but it doesn't always fully protect you.
Here, the same subject was photographed, but this time with a hat shading the lens (and just out of the frame) to prevent the flare. With the many elements and the wide angle of view, wide-angle lenses can generate a lot of flare in an image. Some photographers like the effect, and it's definitely something you can experiment with creatively. Filmmaker J.J. Abrams, for example, has a reputation for adding a lot of flare effects in the CGI effects in his science-fiction movies. In the case of these two images, however, there's no question that the image without the flare is superior.