Viltrox Brings Its 16mm f/1.8 to L-Mount

Viltrox's AF 16mm f/1.8 is now available for L-mount, bringing a bright ultra-wide with a small info screen on its barrel to Panasonic, Leica, and Sigma bodies at a list price of $580. If you shoot night skies, tight interiors, or dim venues, a fast autofocus 16mm at that price gives you another way to gather light without leaning so hard on ISO.

Weather-sealing is part of the package. Christopher Frost mounted the Viltrox AF 16mm f/1.8 L on a Panasonic Lumix S1R II and found a metal body with real heft, a metal mount with a sealing gasket, and a USB-C port for firmware updates. The aperture ring can be set to turn smoothly or click in third-stop steps, which video and stills shooters will both appreciate. The detent between the A position and f/16 is soft, though, so it's possible to knock the lens out of auto aperture without noticing. Frost calls the front screen a bit of a gimmick, then admits it earned its keep when he was focusing on stars in the dark.

The handling details tell you a lot about who this lens suits. The metal focus ring turns smoothly and responds well to the focus motor, and focus breathing is close to nonexistent. Autofocus on the S1R II was silent and accurate but only average in speed, so if you shoot fast action, expect the occasional moment of frustration. The 77mm filter thread is a plus on an ultra-wide, but a standard-thickness filter will add vignetting. Frost's Marumi FIT + SLIM filter worked without trouble, and the lens has no optical stabilization of its own but paired cleanly with the camera's in-body stabilization.

At 16mm, the old 500 rule suggests you can expose for about 31 seconds before stars start to streak. That rule comes from the film era and doesn't account for pixel density. The simplified rule does, and on a 44-megapixel sensor like the S1R II's, it points to roughly 12 seconds at f/1.8 for stars near the celestial equator. You get far less time than most people assume, and aperture fills the gap. Going from f/2.8 to f/1.8 gains you about 1.3 stops, so a shot that needs ISO 8,000 at f/2.8 needs only ISO 3,200 at f/1.8. On a high-resolution body, that difference shows up as cleaner skies and more detail in the foreground. Focus is the other half of night work. Live view at night is often too dark to judge focus, and a lens that displays its focus distance lets you return to infinity reliably in total darkness.

The test results start with a surprise. On Frost's flat test chart, this was one of the few lenses that clearly struggled wide open. The center was perfect at f/1.8, but the corners stayed soft even at around f/4. Real-world landscapes told a different story. At normal shooting distances, the corners were already quite sharp at f/1.8, and at f/2.8, they gained brightness and bite. Sharpness holds roughly steady through f/8 before diffraction softens things at f/11 and f/16. With corrections turned off, distortion is almost absent, a welcome result for architecture and interiors.

Close focus is limited to about 27 cm, so you won't get very close to small subjects. Center sharpness stays excellent at that distance even at f/1.8, though contrast needs a stop down to f/2.8 to reach its best. From there, Frost turns to the conditions this lens will face most often: bright lights in and just outside the frame, point light sources in the corners for coma, sunstars all the way to f/22, and the way out-of-focus highlights render.

Frost's video above has the full results on flare, coma, vignetting, and bokeh.