The Sigma 65mm F2 DG DN Contemporary ($699) is one of the inaugural entries in the company's I Series, a line of slim, quality prime lenses for full-frame mirrorless cameras. Its focal length is an odd one, netting an angle of view tighter than typical standard angle optics, but falling a bit shy of being considered a portrait lens. Photographers who prefer a slightly narrower view of the world will be rewarded, though—the lens is exquisitely built, with optics to match. It's an Editors' Choice winner, not just because of its unique angle of view, but also because of its exemplary performance.

I Series

Sigma places the 65mm F2 DG DN Contemporary in its I Series, a family of built-for-mirrorless prime lenses. It's constructed with a slightly vintage mindset—the aluminum barrel and knurled control rings set it apart from the crowd. Most lenses have moved to polycarbonate construction, which is still plenty professional and durable, but with a distinctly different feel.

It's on sale in two mounts: L-mount, for Leica, Panasonic, and Sigma models, and for Sony's E-mount system. We received the Sony edition for review. Like others in the series, Sigma has worked to keep things small. The 65mm weighs in at 14.3 ounces, and at 2.8 by 3.0 inches (HD), it won't take up a lot of room in your camera bag.

A reversible metal hood is included, as are standard front and rear lens caps. Sigma also includes a metallic cap. It's a smart accessory—it pops on and off easily, and can slip into your pocket, as long as you don't mind getting some lint on its black felt lining. You'll want to stick to the standard cap if you use the hood, though, or when using a filter—the lens supports the 62mm filter size.

It's compatible with full-frame cameras, where it captures an angle of view that's a bit tighter than a typical standard angle lens. With an APS-C sensor, or for Super35 video capture, the angle is what we think of as one for portraits, about the same as a 100mm lens on a full-frame system.

The I Series is young—the Sigma 45mm F2.8, now a couple of years old, set the motif, but wasn't marketed under the banner at launch. It is now, along with the 65mm, the 35mm F2, and the 24mm F3.5. The four are unmistakably related—they share a similar industrial design, one that emphasizes quality, without utilizing massive optics.

They drop some features found on pricier lenses: weather sealing isn't extensive, you just get a seal around the lens mount, and there's no anti-smudge fluorine covering the optics. I'd feel comfortable using the lens in light precipitation, but wouldn't take it out in a downpour.

Handling and Focus

The 65mm F2 includes two control rings, one for aperture and one for focus. The aperture ring sits closer to the mount and can be set from f/2 through f/22 in third-stop increments. There's an A position, which moves aperture control to the camera body, but no way to set the ring for clickless operation, something videographers look for.

Autofocus is quick and quiet. Still photographers won't mind seeing some breathing during focus—the angle of view changes visibly along with focus. It's another drawback for video—you can use the lens for shots with a fixed point of focus with no problem, but racking from foreground to background nets the distracting breathing effect.

If there's a limiting factor in using the lens, it's close-up focus. You'll find yourself pulling back to get some shots, as the camera needs to be at least 21.7 inches (0.55m) away from a subject to get it in focus. At that distance the macro magnification, the ratio of the size of subject in reality to what's projected onto the image sensor, is 1:6.8.

It's in line with what we see from some others, including the Sony FE 55mm F1.8 ZA (1:7.1) and the Panasonic Lumix S Pro 50mm F1.4 (1:6.7). If you're looking for a standard lens that gets you closer to your subject, think about an F2.8 option like the Sigma 45mm F2.8 (1:4) or the Sony FE 50mm F2.8 Macro (1:2).

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As with most small primes, the 65mm Contemporary skips optical stabilization. With a few exceptions, the full-frame mirrorless cameras you'll pair this one with include 5-axis IBIS systems. With the Sony a7R IV, I'm able to get crisp results from the lens and half-second handheld exposures.

In the Lab

I tested the 65mm F2 along with the 60MP Sony a7R IV and software from Imatest. The lens delivers outstanding resolution, about 5,000 lines. There's a slight drop in clarity as you move toward the edge of the frame, but the periphery delivers excellent contrast, even when the lens is shot wide open.

Resolution holds steady as you narrow the aperture, with the absolute sharpest images across the frame coming in around f/5.6. Diffraction starts to soften details around f/8, but is only a real world concern when working at f/16 through f/22.

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You'll enjoy automatic distortion and vignette correction when using your camera in JPG mode. If you opt for Raw capture, you'll need to make corrections yourself, or let your Raw processing software take care of it. Without any adjustments, the lens shows some pincushion distortion (2.7 percent) and dimmed corners at f/2 and f/2.8.

Overall, there's little negative to say about optical performance. The 65mm F2 benefits from its short telephoto focal length—typically lenses of this type deliver excellent results in the lab. The 65mm F2 goes a bit further, delivering results that maximize the potential of the highest-resolution image sensors on the market today.

An Atypical Standard Lens

Sigma is beating its own path with the I Series, and we view that as a good thing. In recent years we've seen a number of big, heavy prime lenses with F1.4—and sometimes brighter—optics. With its 65mm F2 DG DN Contemporary, and other I Series lenses, Sigma is targeting customers who don't need an extra wide aperture, but don't want to lose anything else.

The design philosophy is strong, and consistent, through the line. The 65mm F2 isn't as much of a pancake lens as its wider siblings, but still qualifies as compact, and it comes in at under a pound so it won't make your camera too front-heavy. I paired it with an average sized full-frame camera, but have no qualms about recommending it for use with smaller bodies.

The choice of focal length is what makes this an atypical option. Its angle of view is a little tight for some, but if you love working toward the long end of a 24-70mm zoom, you'll find yourself right at home. It's a focal length that lends itself to subject isolation when working close, and allows you to get a bit more background than a typical standard angle prime when you've got a bit of distance between camera and subject.

It's where personal preference come into play. I don't think I'd reach for the 65mm as my main lens—I'm much more comfortable with something a little bit wider, like the Sigma 45mm F2.8—but photography is an artistic endeavor as much as a technical one. If your eye leans to tighter compositions, be happy to know that the 65mm F2 DG DN Contemporary delivers outstanding quality all around. With so many lenses to choose from, the 65mm stands apart from others, earning Editors' Choice marks in the process.