Sigma’s new 20mm f/2 DG DN lens adds to the already remarkable lineup of I series Contemporary lenses for E and L mounts. With fast, close, accurate autofocus and beautiful optics, the new 20mm is a winner, perfect for anyone shooting landscape or travel photos.

I was a bit surprised when I received the 20mm for testing. Sigma already has a 24mm f/2 lens in its I series lineup of Contemporary lenses. So where would the new 20mm fit in? Once I started using it, though, it was clear why this lens was made. I’ve quickly started to fall in love with the 20mm focal length, all because of this new lens.

Pros

  • Fast and accurate autofocus
  • Sharp optics
  • Clickable aperture dial
  • Some weather sealing present

Cons

Sigma 20mm f/2 DG DN Contemporary — Technical specifications

All technical specifications for the Sigma 20mm f/2 have been provided by Sigma:

  • Lens construction: 11 groups, 13 elements
  • Angle of view: 94.5°
  • Diaphragm blades: 9, rounded
  • Minimum aperture: f/22
  • Minimum focusing distance: 8.7 inches
  • Maximum magnification ratio: 1:6.7
  • Filter size: 62mm
  • Dimensions: 70 x 72.4mm / 2.8 x 2.9 in.
  • Weight: 370g / 13.1 oz.

Sigma 20mm f/2 DG DN Contemporary — Ergonomics and build quality

One thing I love about the Sigma Contemporary series is how solid and compact the lenses are, and how they are all the same form factor. The metal construction is impressive, and it speaks to the lineup’s quality.

On the exterior of the lens, there’s everything you’d expect — an AF/MF switch, along with a focusing ring. There’s also a clickable aperture ring, which is just like the other Sigma I series Contemporary lenses. While I like this, I did find that it isn’t super tight in terms of staying in its position. Meaning, in my bag, if I have it to the “A” position, when I take it out of my bag it might have slid to f/22. Not always … but sometimes. And videographers won’t like the fact that you can’t de-click the aperture ring. But for me, these are minor hassles.

The lens comes with two lens caps — a magnetic lens cap and your standard plastic cap. As we’ve discussed in other lens reviews, the magnetic lens cap is nice, but it’s a pain when you have a lens hood attached. It just doesn’t work well. For me, I left the magnetic cap in the box and stuck with the plastic cap.

The lens does have some dust and splash resistance, but it’s only sealed at the mount. Don’t expect to go out in an absolute downpour with this lens, but it should hold up in light weather and winds just fine. I had it out in a light snow, and experienced zero problems.

Sigma 20mm f/2 DG DN Contemporary — In the field

I was able to spend a few days with the Sigma 20mm f/2, photographing everything from frozen lakeshore landscapes to some architecture and night art installations. I used the Sony a1 and a7 IV cameras during my testing. As I used the lens, it became clear to me who this lens was meant for.

First off, those who are looking for a great wide-angle walk around lens will be nothing but pleased with the Sigma 20mm Contemporary. It’s a great travel lens due to its compact size and wide view. And it’s great for landscape photographers who need a wide-angle lens with some superb sharpness.

But I think it would also serve well for astrophotographers. While I didn’t get a chance to test this specifically, I did capture an art install from the ground looking up. Objects were sharp and autofocus was quick.

Finally, architecture photographers might find this worthy, but given its distortion — which I’ll touch more on later — you will want to ensure Distortion Compensation is on before shooting.

Sigma 20mm f/2 DG DN Contemporary — Autofocus performance

Autofocus was very quick and accurate to lock on to my subject. Even in situations where there were multiple elements moving with high contrast to lock on to, the lens had no issues focusing on the intended subject.

Additionally, focus distance was impressive, offering a minimum focus distance of 8.7 inches (though there were times when I swear I was closer).

Sigma 20mm f/2 DG DN Contemporary — Image quality

Image quality on the Sigma 20mm Contemporary is pretty good. There is some pretty heavy distortion present, but beyond that, it’s improved on some of the flaws of other Sigma I series Contemporary lenses, especially with ghosting and flaring.

The Sigma 20mm is a joy to use, and you’ll get results that you’ll be nothing but happy with.

Distortion control and vignetting

There’s a strong distortion with the 20mm Contemporary. While I expected some distortion, the 20mm goes a little beyond what some might find acceptable. Still, it’s easy enough to correct. It’s just something to be aware of, especially if you’re using the lens to capture real estate or architecture.

One thing to note, however — most Sony cameras offer a Distortion Compensation option. With this option turned on, the distortion I experienced with this lens was immediately fixed.

On the vignetting side, there’s a pretty strong vignette here, too. Throughout my tests, I could notice a vignette even up to f/18, though it’s just slightly noticeable at that level. Personally I love a strong vignette, and don’t typically remove them, as I find it adds character. This is also correctable in-camera or via post-processing, if you prefer to eliminate it.

Ghosting, flaring and chromatic aberrations

Sun stars were easy to get with this lens, as shown above. There’s some very, very minor flaring and hardly any ghosting, making for an improvement over the Sigma 24mm f/2 Contemporary. I saw very little lack of contrast when shooting into the sun, which was good to see.

In terms of chromatic aberrations, if there are any, they are very, very slight. I saw some very minor purple fringing in one photo, but it was only noticeable at a 100% zoom, and was easily corrected in post-processing.

Sharpness

Just like the other Sigma I series Contemporary lenses, sharpness is a big positive with the 20mm. Details are sharp in the center of the lens at f/2, with a nice fall off to the edges. By the time you get to f/11, you’re dealing with a fully crisp, tack-sharp image.

Bokeh

While I wouldn’t necessarily need bokeh on a wide-angle prime, the 20mm performs well in this category. Bokeh balls are somewhat catseye, and there’s a softness to them that makes the subject pop away from the background. Depth of field on Sigma’s I series Contemporary lenses has always been a strong point, and the 20mm is no different. The character the 20mm has in this department is second to none.

Color rendition

Colors are pleasing to the eye, and are very true to tone, more so than a lot of lenses I’ve tested. This is nice, as it offsets Sony’s green colors that their bodies often have.