Crazy Wide, Crazy Fast: Fstoppers Reviews the Sigma 14mm f/1.8 DG HSM Art Lens

by Alex Cooke March 16, 2018 21 Comments

Every once in a while, a lens comes along that truly breaks new ground for one reason or another. Such is the Sigma 14mm f/1.8 DG HSM Art, which has an aperture over a stop faster than its competitors and is the fastest full-frame lens under 20mm. Of course, extreme lenses often have compromises of some sort, so how does this one perform? In short, extremely well. Check out our full review.

The Sigma Art series has churned out some awesome lenses that have really shaken up both the lens market and how photographers view third-party lenses in general. Along with some staple lenses have been so more unique offerings, and the 14mm f/1.8 DG HSM Art falls squarely in the second camp, offering an insanely wide aperture for its focal length. This should have astrophotographers and landscape shooters who like to shoot at night drooling, as the increased aperture means lowers ISOs and increased detail, particularly important as there's a time limit on exposures of the night sky before star trails become visible due to the rotation of the Earth (unless one is using an equatorial mount). The lens is also intriguing for event photographers and anyone else who could use a high-quality ultra-wide-angle lens, including architectural photographers, environmental portraitists, and more.

Build Quality and Ergonomics

Build quality is of a typical Art series level. The barrel is made of TSC (thermally stable composite) and feels solid. The focus ring is large and well damped with a good grip, lending itself to precision turns. The lens is weather-sealed, and in my experience, it did perfectly well with some light snow and rain. Like the rest of the Art series, it's a good looking lens with the smooth black finish giving it a modern, elegant look. The distance scale is helpful if you're zone-focusing or looking for the hyperfocal distance, particularly since you'll often find yourself manually focusing in a lot of situations where you'd use this lens.

It's a heavy lens, coming in at 2.6 lbs (1,170 g), but that's the price you pay for that crazy aperture. That being said, the lens balances well and isn't front-heavy, so aside from the sheer bulk, it handles well. The hood is non-removable, but with that large, convex front element, I prefer it that way. Also note that because of the front element's shape, screw-on filters cannot be used.

Autofocus

This is far and away the weakest part of the lens. While you may not think you need to worry about autofocus performance too much at this wide a focal length, that maximum aperture does create a noticeably finite depth of field, particularly at closer focal distances (see below). Simply put, it's not great. Focusing speed is quick and accuracy is quite good when it finds it, but consistency is a definite weak point. It does use Sigma's very quiet and fast HSM (Hypersonic motor), which should be pleasing for video shooters. Nonetheless, I found the lens noticeably missing in some rather easy scenarios that shouldn't have challenged it and in which were I working, I would expect it to perform without question. Performance was particularly bad in peripheral autofocus points on my 5D Mark IV, which has a very strong AF system. What's more frustrating is that the problem was mostly one of consistency, which cannot be remedied by an AFMA: in a test where I put the autofocus point on a tree about 10 feet away with a light background (at an exposure of 1/100 s at f/1.8 and ISO 100), the lens would oscillate between nailing the focus and ending up 20 feet behind the tree with no rhyme or reason.

The one piece of good news is that most situations you might find yourself using such a lens in generally allow the time for or even require manual focusing. In fact, astro, landscape, and architectural photographers can all look past this. If you're considering this lens for events work, do keep this in mind, however. There's also calibration via the Sigma USB adapter, but I found the error to be one of low precision, not low accuracy, meaning an AFMA adustment isn't going to help.

Bokeh, Flare, Aberrations, and Distortion

Your first thought might be: "bokeh? What is he talking about?" Yes, it's a 14mm lens, but that maximum aperture does make it possible to throw backgrounds reasonably out of focus if you keep the subject close to the lens and the background far away. The effect diminished quickly with distance, though, so it's best done at or near the minimum focusing distance of the lens. To see what I mean, notice how the tree and lights change with just a few inches of movement (both taken at f/1.8):

1/80, f/1.8, ISO 800

As you can see, the effect diminishes very quickly with just a little more subject distance, but nonetheless, the bokeh that is there is nice: it's smooth and the rounded nine-blade diaphragm makes pleasing renderings of light sources. Some Sigma Art lens are known for having slightly crispy or busy bokeh, but with the 14mm, everything was buttery smooth.

Flare control is about as good as you can ask for. The example below is the worst flare I ever got in my time with the lens; you can see it on the horse's blanket near the neck (it doesn't get much worse even if you open up the aperture). Also note that the 9-blade aperture creates 18-point sun stars.

Vignetting, MFD

Vignetting is quite good considering this is such an extreme aperture for the focal length. It's certainly noticeable, but it doesn't bother me, as I think it frames the subject nicely without being over the top; nonetheless, you can easily clean it up in Lightroom. I'll put it this way: if you stop the lens down to the maximum aperture of all its competitors (f/2.8), the vignetting is comparable or better than them. With a minimum focusing of 10.6", which equates to a maximum magnification of 0.10x, this lens isn't going to win any awards for its macro capabilities (indeed, most ultra-wide-angle lenses sit around 0.15-0.20x), but it's rare if ever you'll find yourself in a situation in which you're using a 14mm lens and wishing for a shorter MFD. It didn't bother me in practice.

Image Quality

Overview

I could blabber on for paragraphs about the specifics of it, but let me sum it up in one word: wow. This lens delivers. Images are sharp, contrasty, and have great bokeh, better than what I've seen out of some other Art lenses.

1/320, f/4, ISO 100 (Like any wide angle, if you don't keep your sensor parallel to the buildings, they'll appear to tilt. This means you often need to choose between that effect or lots of foreground in the shot.)

What You're Really Here For: Quality at f/1.8

What's the fun in buying a crazy aperture lens if the image quality isn't there when you shoot it wide open? The good news is that it's definitely there. Time and again, I was astounded at how sharp the lens is wide open, made even more impressive by the fact that its aperture is so extreme relative to its competitors. This is a game-changer for landscape, events, wedding, and street photographers, as you can now shoot in far lower light levels with high image quality. This means lower ISOs and/or faster shutter speeds, always two good options to have available to you.

1250, f/1.8, ISO 100

The benefit of having great image quality at max aperture is the ability to handhold at lower ISOs (1/60, f/1.8, ISO 3,200)

Sharpness and Contrast

Sharpness improves noticeably when you stop down even a third of stop, continuing to improve to pin-sharp levels. Contrast is quite good as well, typical of an Art series lens.

For an ultra-wide-angle lens with a wide aperture, corner sharpness is very good, becoming excellent as you stop down. Nonetheless, it was good enough wide open that I was never bothered by it, which is more than I can say about some other ultra-wide-angle glass. Combined with the good vignette performance, it creates edge-to-edge image quality that should please most discerning viewers.

Aberrations and Distortion

Chromatic aberration is very well controlled: it never stretches wider than a few pixels if it appears at all and is easily corrected with one click in Lightroom. It's not something I would worry about with this lens. Barrel distortion is present, but I would generally say unless you're shooting brick walls or specifically looking for it, you're unlikely to notice it.

Coma

Considering this lens screams "astrophotography," this is the topic a lot of you are probably waiting to hear about. A wide-aperture, wide-angle lens isn't much use for astrophotography if all the stars have wings on them and aren't rendered as point sources. Simply put, coma is not perfect, but it's very good on the Sigma. Check out the two shots below:

As you can see, stars in the corners do show some coma, but the effect is not extreme and generally limited to the extreme corners. It's not the best performance I've seen, but it's more than good enough to make the lens useable for all but the most discerning astro and landscape photographers. I was quite pleased with the result.

Would I Buy It?

This is a tough question. Seeing as this is a lens I would manually focus all the time (and that I don't particularly trust its autofocus anyway), the question becomes if I'm willing to pay over five times as much over something like the excellent Rokinon 14mm f/2.8 for a modest increase in image quality and the massive increase in aperture. In fairness, the Sigma is actually priced well below the Canon EF 14mm f/2.8L II USM, which maxes out at f/2.8, so that's not to imply it's overpriced. It's more a question of need. If you're an astrophotographer or a landscape photographer doing a lot of nighttime work, I would say that it's absolutely a worthwhile investment that you'll be glad you made. If you're someone like an events photographer, the question is a little trickier, as you'll need to consider the mediocre autofocus performance and how often you need to shoot that wide. For me, I eventually decided that as much fun as this lens is (and let me emphasize that it's one of the funnest lenses I've ever shot with), the percentage of times I need f/1.8 out of an ultra-wide-angle lens versus f/2.8 wasn't enough to justify purchasing it. It's a very personal decision, though, and you may feel differently.