Sigma 18-35mm f/1.8 Review: The Best Low-Light Zoom Lens By a MileMichael Hession8/16/13 1:40pmFiled to: lightning reviewphotographysigmalenses722EditPromoteShare to KinjaToggle Conversation toolsGo to permalink Zoom lenses are the quintessential frenemy of photographers everywhere. They provide great versatility, but not without trade-offs such as weight and aperture size. Sigma's new lens brings zooms where they have rarely ventured before with an unprecedented f/1.8 aperture. The future is bright. What Is it?An $800 wide-to-medium angle zoom lens for Canon, Nikon, or Sigma DSLRs with APS-C sized sensors. It has an 18-35mm focal range and an f/1.8 aperture.Why Does It Matter?It's got an aperture at f/1.8, a spec previously found only in prime lenses and unusually wide for a zoom. That means the lens is more sensitive to low light than most high-end zooms, which top-out at f/2.8. DesignSigma did an outstanding job making a sleek, solid-feeling lens with great tactility. It uses a material called Thermally Stable Composite, which has a feel that combines the feel of metal and of plastic, with a nice matte finish. The rubber zoom and focus rings are nice and wide, with great resistance. Even the lens cap is well-designed with a rim that lies flush with the lens, and a pinch fastener that isn't a fuss.Using ItIn the context of zoom lenses, the Sigma 18-35mm is a pleasure to use. It's a tad on the heavy side, and not compact by any means, but it's nothing outlandish if you're used to carrying around zooms. Wide-open at f/1.8 (click to download full-size image) Stopped down to f/5.6 (click to download full-size image) The comfort of being able to open up that aperture in low light is priceless. The biggest surprise is the performance. You might expect a headline feature like f/1.8 aperture to necessitate certain sacrifices. It doesn't, at least not when it comes to image quality. Yes, when wide open at f/1.8, photos are softer with some vignetting in the corners. But that's the case with almost all wide-aperture lenses. When stopped down, the Sigma is plenty sharp. No, it's not as sharp as a high-end prime, but it's still good. The lens has a minimum focus distance of just under 12 inches, and autofocus is snappy and silent, with no extending barrel. Advertisement Advertisement In an ideal world, this lens would offer a little more scope at the wide end. 18mm is the full-frame equivalent of about 29mm on a 1.6x crop sensor. That's acceptable, but not fantastic if you are going for really wide shots. click to download full-size image click to download full-size image click to download full-size image The Best PartYou no longer have to sacrifice aperture size when shopping for a zoom lens. If you are a photojournalist, concert, or documentary shooter with a cropped sensor DSLR, this lens is a godsend.Tragic FlawThere's no image stabilization. That one feature would have skyrocketed this lens into must-have territory for video shooters especially. It would also meant a much higher price, though.This Is WeirdWe did notice a decent amount of purple fringing around highlights. This is very easily fixed automatically in Lightroom or Photoshop, so we don't consider it a major flaw. Test NotesWe shot with the lens on a Canon 7D.We directly compared shots with a Canon 24-105 f/4. In terms of sharpness, the two lenses were nearly identical.If you are used to a zoom with image stabilization, you might want to bump the shutter speed up on the Sigma a bit more than you are used to in order to prevent shaky images. Sigma says a Pentax mount version is in the works. We would love to see versions of this lens for mirrorless systems as well, such as an Sony E-mount or micro-four-thirds mount version.Should You Buy It?In almost all cases, if you have regular need for a serious zoom lens, then yes. Unless you have a niche concern like image stabilization for video, or need a longer focal range, the Sigma is a great replacement for your current walk-around zoom. The price is an extremely reasonable $800, and there is currently no lens out there quite like it.