Readers know that I am a fan of fast glass. I love the flexibility it gives me and I tend to shoot fast lenses wide open because of that flexibility. I have no fear of flash, I just like the ability to make an image wherever I might want to. My latest opportunity is the review of Sigma's ART series 20mm f/1.4
Like all the fast ART series lenses, this lens is on the larger size and could be considered heavy. I was speaking with another photographer who loves the ART quality but would like to see a slower set of lenses specifically for smaller size and less weight. While I am not convinced that there would be significant demand for such things since the OEM candidates are already there, of very good quality and well priced, but to each his or her own. For me, speed counters weight. Your mileage may vary, but size and weight do not detract from the excellence of this lens in my use cases.
Yes, I said excellent. Again. This is the fourth of the ART primes that I have shot and every one of them has been superb. In some cases, like this one, finding an alternative will be very tough because super fast twenties has not been a big deal. Now I think that it could be. And for those seeking superlative image qualities in a wide angle, should be.
This is a full frame lens, so on a crop sensor will look something like a 30mm or so. That's not awful but is very close to 28mm, a prime look that I never personally cared for. On a full frame, this lens rocks. You get the very wide field of view, incredible light gathering capability, minor vignetting until f/2.2 or so and very quick and smooth autofocus. Is the 20mm a full frame only lens? In my opinion, yes it is. On a crop sensor you need something in the 10mm to 12mm range to get this look and one of the reasons most landscape creatives shoot full frame is to get access to superlative and fast very wide glass.
The challenge with very wide lenses is to watch to maintain parallelism between the subject and the sensor plane lest things start to look like they are falling over. While this can happen more readily, it is very pleasing to see that the Sigma 20mm maintains a proper rectilinear perspective without annoying barrel distortion. For those whose tighties become constricting over such thoughts, Lightroom already has a lens correction algorithm in place resulting in very clean images. Testing with and without the lens correction, I found very minor barrel distortion and minor vignetting on the short side of the image. The LR corrections eliminated these issues, and I confess that I used LR to put some minor vignette back into the image, not that you could tell without me so advising you.
The other benefit of the 20mm is that depth of field is enormous. At a primary subject distance of 20 feet, the area of focus runs from just under 13 feet to just under 57 feet at f/1.4 !!! As a certain interesting haired fellow has been known to say "that's yuge!" For landscape shooters, this means that at a median aperture, your total depth of field when focused at 20 feet is 4 feet to infinity, perfect for huge vistas with a close up subject in frame to provide scale. Shooting at f/16 on a sunny day your depth of field is 1 foot to infinity. That, my friends, is awesome. The Sigma 20mm ART sells for $1,199.99 CDN in Canon, Nikon and Sigma mounts. That's the same price as the Tokin Firin f/2 for Sony and only $200 more than the Nikon 20/1.8. I've not shot the Tokina, but I have shot the Nikon and while it is an excellent lens, I would choose the Sigma for the nominally higher price to get the extra lens speed. The Sigma also focuses surprisingly close. In a lot of cases, this can make the subject look badly distorted. I am not in any way possessing the talent of Joe McNally, but Joe can shoot portraits with a 24mm and I think you could, with sufficient practice, do that with the 20mm without everyone looking like Pinocchio on a fib binge. There is an image of a tree trunk with snow in the samples and I was literally inches away when I shot it. Very impressive.
The Sigma 20mm has a permanent petal shaped lens hood. A hood, in my opinion, is a necessity on any lens for its contribution to contrast and flare control. The front element is quite bulbous, and so there is no provision for front mounting of filters. While I do not advocate "protection" filters, the ability to use polarizers and neutral density filters would be important to any serious landscape creative. I checked with the folks at Lee Filters, makers of the famous Big Stopper 10 stop neutral density filter. Their SW150 system filters will work, all you must do is purchase the mounting kit for the Sigma 20mm f/1.4 This is the same style of kit as for Nikon's 14-24 which uses a compression fit system that works very well indeed. Thus, the ability to use this super wide lens, along with the ability to use a high quality polarizer and a high quality ND makes the Sigma 20mm a killer choice. While a filter system does incur a higher investment, I cannot imagine a committed landscape artist not wanting such filters from time to time.
All the samples were shot on a Canon 5Ds with the Sigma 20mm f/1.4 ART. All but the school were three shot brackets pulled together in Lightroom and processed. I only shoot in RAW so post processing is a given. What I particularly liked was how much I was able to get out of the shadows and the highlights in the 0,0 image and how much more I could get using a simple 32 bit HDR conversion. We talk about dynamic range a lot and while this is often relegated to purely the sensor, the sensor can only eat what you feed it.
If your work is done on a full frame, and you want something wider than 24mm but not so wide as a 14mm with the related costs and added weight, I do not think that you can miss with this Sigma 20/1.4 I am biased towards great fast glass, and this is the fastest 20mm I have ever seen and in my testing gives nothing up to the slower OEM lenses other than being a bit bigger and a bit heavier. Giving those thoughts due consideration, I would choose the Sigma every time.
Shooting very wide lenses is a skill that we can all build. It's like learning to use any other focal length well. Repetition and review become the mothers of skill. This lens, like the other ART series, get's a 5 Star Rating.