As the standard lens for the top-end Phase One XF 100MP, you'd expect the Phase One Schneider Kreuznach 80mm LS f/2.8 ($3,290) to deliver serious image quality. It doesn't disappoint, notching very strong numbers when paired with the 100-megapixel camera system, and it incorporates a leaf shutter into its design in order to sync with flashes at very high speeds, as short as 1/1,600-second. It's not optically perfect, as it trades some performance for a light, compact design. It's an excellent performer, though, and a solid choice for Phase One and Mamiya system owners in want of a standard-angle prime.

Design
The 80mm LS f/2.8 is part of the Blue Ring series from Phase One, which indicates that it is built with stricter tolerances when compared with older glass like the LS 80mm f/2.8 we reviewed in 2014. It's an attractive hunk of glass, with a metal finish, a knurled manual focus ring, and a matching metal lens hood. Th front element supports 72mm filters.

At just 3.4 by 2.5 inches (HD) and 1.1 pounds, it is one of the smaller, lighter medium format lenses available. Its design doesn't incorporate optical image stabilization, but that's a feature you don't often seen in medium format glass. Phase One doesn't offer it in any of its lenses, not even telephoto or zoom designs.

Focus is controlled by a narrow ring at the base of the lens. Twisting it switches between manual and automatic operation. A focus scale is at the top of the barrel, marked in feet and meters, along with a corresponding depth of field scale with full-stop marks down to f/22.

The lens is capable of locking on to subjects as close as 2.3 feet (0.7-meter) from the image sensor. That delivers a 1:6.7 maximum magnification ratio—not the best you'll get in a standard angle lens, but pretty good for medium format. Aside from those times when I was specifically going after a macro shot, I didn't find myself limited by the minimum focus distance, and if your shot is on the wide side you have plenty of room with which to crop when working with a high-resolution image sensor.

Image Quality
I tested the lens with the XF 100MP. It put up incredible numbers on the standard center-weighted Imatest sharpness test, notching 4,539 lines per picture height. We don't yet have a baseline as to what kind of performance to expect from a 100MP camera, but field tests confirm that you won't be wanting in terms of detail. When viewed at full resolution you can see the individual hairs in the eyebrows and eyelashes of the model pictured above.

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There is a drop in fidelity as you move away from the center of the frame. But at f/2.8 the edges still show 3,970 lines. That's plenty of resolution, and in most f/2.8 shots the periphery will be blurred due to the shallow depth of field you get at such a wide aperture.

At f/4 the average score improves to 4,809 lines, and edges get much closer to the center, hitting 4,650 lines. That trend continues at f/5.6 (5,142 lines), f/8 (5,849 lines), and the peak setting, f/11 (6,273 lines). Diffraction starts to take its toll at narrower apertures, dropping the score to a still-solid 4,339 lines at f/16 and a disappointing 3,873 lines at f/22.

There is some visible barrel distortion, about 1.7 percent. That will add an unwanted outward curve to straight lines in an image. However, it's easy enough to correct for this in Capture One Pro 9. Also easy to correct is corner illumination. Imatest's Uniformity tool shows that corners are about 2.5 stops (-2.5EV) dimmer than the center of the image at f/2.8 and show -1.5EV at f/4. But the lens correction tool allows you to brighten them with ease, and illumination is even from edge to edge at narrower apertures.

Conclusions
The Phase One Schneider Kreuznach 80mm LS f/2.8 is the lens you get if you buy a Phase One system in a bundle, and there's a good reason for that. It's compact and light, covers a standard angle of view, and its f/2.8 aperture is on the wide side for a medium format lens. You can shoot at a wide aperture in order to net a shallow depth of field and get crisp results, or stop down the lens to maximize sharpness. And because there's an in-lens shutter, you can sync with an external flash at 1/1,600-second. It's not perfect—it shows some barrel distortion, and corners are on the dim side at f/2.8 and f/4—but those compromises aren't huge concessions when you consider its size and price point. If you're a Phase One owner with an older vesion of the 80mm, it's certainly worth spending a bit extra to get it along with the new XF body (when bought together the lens only adds $1,000 to the price). And if you're new to the system, it's an excellent choice as an all-around optic.