Sigma Sigma Art Sigma 17-40mm f/1.8 DC Art Lens (L-Mount) Review

The Sigma 17-40mm f/1.8 is a sharp, unique constant-aperture zoom for APS-C L-mount. Its f/1.8 speed is awesome, but bokeh and close-focus are weak. At $919, it's a specialist's tool, not an all-rounder.

Sigma's 17-40mm f/1.8 DC Art is a weird, ambitious lens. It's a constant f/1.8 zoom for APS-C L-mount cameras, which is basically unheard of. That means you get a bright, fast aperture across the whole zoom range, from a wide 17mm to a short-telephoto 40mm equivalent.

It's the spiritual successor to the legendary 18-35mm f/1.8 Art, but now designed for mirrorless. The build is solid, it's got internal zooming, and it's surprisingly compact for what's inside. But that f/1.8 promise comes with some trade-offs.

Optically, this lens is a beast. It lands in the 94th percentile for sharpness in our database, which means it's genuinely excellent. The stabilization is also top-tier at the 85th percentile, great for video and low-light stills. The autofocus is where things get interesting. It's rated as 'fast' by Sigma, but our percentile data puts it at a middling 45th. It's perfectly fine for most situations, but don't expect lightning-fast tracking for sports. The real letdowns are in the bokeh (12th percentile) and macro (17th percentile) categories. That f/1.8 aperture doesn't translate to creamy backgrounds or close-focusing magic.

At $919, this lens isn't cheap. You're paying a premium for that constant f/1.8 zoom, a feature you simply can't get anywhere else. If you're an APS-C L-mount shooter who lives in low light or loves shallow depth of field across a zoom range, this is your only option. For everyone else, the price might be hard to swallow, especially when you consider its weaknesses in bokeh and close-up performance.

This lens exists in its own niche. The closest historical competitor is its predecessor, the Sigma 18-35mm f/1.8 for DSLRs, which this lens updates for mirrorless. Compared to a prime like the Nikon Z 35mm f/1.8 S (a full-frame lens), you'll get more versatility but likely less optical perfection and background blur. Against a standard zoom like the Panasonic 14-140mm, you're trading massive range for that constant bright aperture. It's not competing with the Viltrox or Meike primes on price or bokeh; it's competing on the unique proposition of a fast zoom.

Skip this if you're a portrait photographer looking for dreamy bokeh. Our data shows it's terrible for that, scoring a dismal 31/100. Also, if you're on a tight budget or shoot full-frame, there are better and cheaper options that will suit you more.

Buy this lens if you're an APS-C L-mount photographer or videographer who needs a versatile, sharp, and consistently fast lens for run-and-gun situations, events, or low-light work. The constant f/1.8 is a game-changer for that specific use case. Just know you're not getting a portrait bokeh monster.