Like many photographers, I was surprised when Sigma announced that they were releasing the Sigma 18-35mm F1.8 DC HSM, a constant f/1.8 zoom lens for crop sensor digital SLRs. After all, f/1.8 prime lenses are rare enough these days, and zoom lenses faster than f/2.8 number exactly two (both from Olympus and both well over $2,000). So, to have Sigma announce they were offering an 18-35mm f/1.8 lens, that would be priced at $799, was pretty amazing.
An f/1.8 lens is one and one-third stops faster (gathering 2.42 times more light) than an f/2.8 lens. In other words, a photographer with an f/1.8 lens can use a faster shutter speed, or lower ISO, for a given exposure as compared to making the same image with an f/2.8 lens. Back when I was working as a wedding photographer, often in dim reception halls, I was constantly balancing the need for a faster shutter speed with the need to keep my ISO as low as possible. In a situation like that, when you are at the maximum ISO you feel comfortable using, the one and one-third stop difference between 1/13 of a second and 1/30 of a second can be the difference between a crisp image and a blurry one.
An 18-35mm lens on a crop sensor DSLR offers a field of view approximately equivalent to a 27-53mm on a full-frame body. This is a bit narrow compared to other wide-normal zoom lenses, and hardly the focal range that some working photographers might think of as ideal. Consider, however, how many images from the “golden age” of documentary photography were made with f/1.8 lenses in this range. How many photos that graced the pages of LIFE or National Geographic were taken using a 50mm f/1.8, 35mm f/1.8 or a 28mm f/2? The Sigma 18-35mm puts all three of those lenses in your hands at one time.
Like the other lenses in Sigma’s Art line, the 18-35mm f/1.8 lens has a bit of a utilitarian look to it. With its matte-black finish, white lettering and only the chrome “A” badge to call attention to itself, the 18-35mm isn’t flashy. Personally, I view its pared-down, functional design as a positive. It gives the impression that it’s a tool rather than an accessory.
The 18-35mm has a very solid feel to it. In part, this is due to its size and weight. At 3.1 x 4.8 inches, and 28.6 ounces, it compares to f/2.8 lenses with a significantly larger zoom range. The solid feel also comes from the fact that it is simply a well-constructed lens. The mount is chrome-plated brass and much of the chassis is metal. To reduce weight, sections of the outer shell are made from Sigma’s Thermally Stable Composite (TSC). Sigma came up with a very nice material here. If composite material in a lens makes you think of cheap plastic kit lenses from the 1990s, you owe it to yourself to see how the technology has evolved.
The 18-35mm’s filter size of 68mm may disappoint those photographers who are used to the more standard 77mm size of “pro” lenses. I think most of us, however, would rather pick up a step ring if needed, and spare the added size and weight.
The focus and zoom rings have a nice grip to them without being completely clad in rubber. More importantly, both rings are very well damped and feel smooth in use. The underside of the area between the focus and zoom rings is also lightly knurled, presumably to provide a better grip when bracing the camera for shooting or changing lenses.
Performance and Handling
Like many high-end lenses, the 18-35mm handles very well despite its size. Perhaps unsurprisingly, it balances much better on a larger DSLR like the Canon EOS 7D. On a smaller, lighter body, the 18-35mm feels a bit front-heavy and awkward, but I took some time to try it on Canon’s smallest and lightest DSLR, the EOS Rebel SL1, and wasn’t overly bothered by the balance issue.
The zoom and focus rings are a pleasure to use. Both focusing and zooming are internal actions. In practical terms, internal focusing means that the front element will not rotate, making polarizer use much easier. Internal zooming means that lens length won’t change as you zoom. We’ve come to expect internal focusing on a lens in this class, but internal zooming is still something worthy of note. Driven by a ring-type ultrasonic focus motor, autofocus is quick, accurate and nearly silent. Manual focus can be applied at any time by simply turning the focus ring. Close focus is 30cm, which matches or beats most lenses in its class.
Overall, the image quality of the 18-35mm is stellar. Image quality at 18mm and maximum aperture was impressive for a lens of this speed and focal length. Sharpness is excellent in the center of the image and only softens slightly at the corners. Distortion and chromatic aberration are all very well corrected. Even the vignetting is slight and, in my opinion, pleasing to the eye. Stopping down slightly improves sharpness, but it is clear that this lens was designed to be used wide open. Performance is reduced slightly as you progress through the zoom range and stopping down to f/4 is required for peak sharpness.
The Bottom Line
Sigma has been on a roll with its Art lenses recently, and the Sigma 18-35mm F1.8 DC HSM is no exception. Image quality is excellent, build quality is solid and the price is outstanding. Using it made me remember those dark reception halls where that one and one-third extra stop of speed from an f/1.8 lens might have made the difference between an unforgettable shot and an unusable one. Like most specialty lenses, the 18-35mm isn’t going to be for everyone. While 28-56mm may be a classic “street” photography range, it is a little narrow for many photographers, particularly when excellent lenses such as Canon’s 17-55mm f/2.8 are available (albeit with a $250 pricing premium). The 18-35mm is also not a small lens and perhaps won’t lend itself well to some of the candid street shooting that its focal length and speed seem logical for. However, at the end of the day, this is a truly unique and amazing lens. If you like low-light photography and shoot with a crop-sensor DSLR, you owe it to yourself to take a serious look at the Sigma 18-35mm.
Sigma 18-35mm F1.8 DC HSM
Pros: It’s a f/1.8 constant zoom; excellent image quality; classic documentary focal range; solid build; hood included; priced lower than expected
Cons: Size and weight; crop sensor only; short zoom range; still not an inexpensive lens
Price: $799; available in Canon, Nikon and Sigma mounts