I consider ultrawide zoom lenses to be primarily special-effects tools and the Sigma 8-16mm certainly falls into this category. Let’s take a close, undistorted look at its features and abilities.
The Sigma 8-16mm f/4.5-5.6 HSM Zoom is a DC lens, designed to be used with APS-C or Four Thirds sensor type DSLRs, and the image fills the frame. Use it on a full-frame Canon or Nikon, however, and you’re likely to get something closer to a traditional fisheye-type look with a rounded image (if not, necessarily the full circle).
At 8mm, the lens covers a 121.2-degree angle of view, which lets you get a lot in—35mm equivalent approximately 12mm on an APS camera or 16mm on a Four Thirds system camera. At 16mm that view is cut to about 75 degrees, still a respectable ultrawide area of coverage—35mm equivalent to approximately 24mm on an APS camera or 32mm on a Four Thirds system camera.
The Sigma 8-16mm is available in Canon EOS, Minolta/Sony, Sigma, Pentax, and Nikon mounts, and can be used on Four Thirds cameras via an adapter.
Depth of field: At 8mm and f/11, everything from a few inches away to infinity was in focus.
In the hands
With its 15 element, 11 group lens array, there’s a lot of glass in this lens. The result is that it weighs over 19 ounces, a substantial heft. The flecked black surface has a solid look and feel, while the two half-inch-sized, ribbed focus and zoom rings offer a good, comfortable hold. The zooming action is smooth with just enough resistance. The entire focus range is covered in an approximately 90-degree turn. The focus action is smooth with less resistance than the zoom action. I do wish that when manual focus was disengaged and AF was on, that the resistance on the focus ring was less, indicating to the user that you were in AF mode. Many other lenses do this.
There is a built-in petal-type sunshade, which is augmented by a solid sunshade that can be attached when using the longer focal settings and also accommodates the lens cap. The solid sunshade must be removed when at the widest angle, otherwise it will show up in the picture.
In the field
The Sigma 8-16’s HSM focusing was quiet, quick, and accurate. Most of the time I didn’t need it, since at f/11 the hyperfocal distance covered pretty much everything from a foot or so in front of me to infinity. However, you can focus to within 1-2 inches of the front of the lens. Be warned: The distortion at this distance will be amazing!
Far out? No, the big granite ball is about a foot from my lens but looks farther way at 8mm. Note the vignetting, especially in the sky towards the left corner. Note that the linear distortion, while apparent, is strongly corrected and therefore not as pronounced as one might expect.
At 12mm, much optical distortion is well under control (no more curvy lines at the edges).
At 16mm, image quality approaches standard focal range.
It is difficult to do edge-to-edge sharpness tests on ultrawides, and I didn’t even try. I can report that center sharpness was very good at all focal lengths. Not surprisingly, pillow distortion was very noticieable at 8mm, and very slight pincussion distortion shows up at 16mm. In the middle setting, 12mm, the pillow distortion is virtually unnoticeable. So yes, you can shoot some architecture with this lens at the longer settings as long as it isn’t mission critical type work. It is surprising that the linear distortion in this lens is quite well-corrected compared to other ultrawides, so that while its focal length indicates that its range is in a near-fisheye territory, it doesn't really produce fisheye-type results.
There is marked vignetting at 8mm, which again is no surprise given the optical limits this lens faces. From 12mm on, vignetting is much less noticeable and it’s virtually gone by 16mm. Flare was very well controlled throughout the range, thanks to the aspherical and FLD glass elements. In fact even shooting into direct sunlight (something that’s hard to avoid at 8mm) I saw very little flare, which is impressive.
Conclusion and recommendation
Sigma 8-16mm f/4.5-5.6 HSM is a solid lens, and produced the kind of images I’d want out of a specialty ultrawide zoom lens: Funky, clear and fun. Distortion is there, as expected, but the lens can double as an almost-standard wide angle lens at the 16mm setting, giving it some versatility (although admittedly, with a maximum aperture of f/5.6 at 16mm it’s limited at that focal length). It is relatively heavy (compared to, for instance, the Pentax 10-17mm f/3.5-4.5) but it goes wider than almost any other ultrawide I’ve seen (The Olympus 7-14mm f/4 is a notable exception; Most ultrawides stop at 10 or 12mm).
But the bottom line here is that this is a fun lens and you can do some serious special effect photography with it. Grab one and enter the fisheye distortion zone!