I bought this lens for night astrophotography primarily. This lens does have many great uses at all apertures. Very sharp, great resolution, some distortion which is normal with such a wide angle 20mm lens, color and contrast seem to be accurate. Focus accuracy and speed are pretty good.

During the last decade the ultra-wide segment has been dominated by zoom lenses but it seems as if prime lenses are about to enter a renaissance. Lately Nikon released a 20mm f/1.8 and we've seen a bunch of updates from Zeiss and some promising announcements from a new player (irixlens.com).

Sigma's Art series of f/1.4 prime lenses has delivered consistently strong performance, and its latest entry, the 20mm F1.4 DG HSM Art ($899), is no exception. It manages to capture sharp, ultra-wide images, a heck of a lot of light, and focus close so you have the option of blurring the background...

Sharp from edge to edge; Minimal distortion; Short minimum focus distance; Available for multiple systems

Heavy; Dim corners and edges; No support for filters

The lens has good contrast and is sharp as a razor. Good in low light. AF is good, the same as the 35mm 1.4 art. Hoping they can come up with a way to put a filter on it. Would like to use my neutral density with this.

Great Picture Quality

Heavy

Previously not available in focal lengths wider than 24mm, the ultra-wide f/1.4 aperture is now available in the 20mm focal length thanks to Sigma, allowing a wider angle of view to be captured in very low light conditions.

At last, a super-wide lens that's sharp and quick! Combining this lens with ISO 6400 on the Canon 5d Mark III and the noise reduction of Lightroom, I am impressed at the scenarios I can shoot hand-held with virtually no light. Candlelight just No issue.

sharp and great colors

no cons

The Sigma 20mm F1.4 DG HSM is a very fast, tack-sharp prime lens in Sigma's excellent Art series, and also a unique lens to boot, as it's the only 20mm lens in the World to offer an f/1.4 aperture.

Sigma's latest offering in the Art Lens portfolio is an ultra-wide 20mm full frame lens, for Nikon, Canon and Sigma fit. Not only that, but an extra-bright f/1.4 aperture makes this a desirable optic from the start. All looking good in theory, now let's see how it handled and performed in practice.

Superb optical quality; Well made; High control of CA; Excellent handling; Excellent AF performance

Price penalty for f/1.4 aperture; Heavy and bulky; Not weather resistant

For the past couple of months, I've been incredibly busy testing gear from many different manufacturers. But as many of you know who have been readers of this blog for a while, I switched all my DSLR lenses over to Sigma a couple of years back. Why