Sigma 20mm F1.4 DG DN Art Review
By Yvonne
2022-09-26

Sigma 20mm F1.4 DG DN Art is a great lens for photographers, especially strophotograhs. It has a wide field of view and a well-corrected optical formula.

Sigma 20mm F1.4 DG DN Art Review

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Let's get to the bottom

Sigma 20mm F1.4 DG DN Art is a great lens for photographers, especially strophotograhs. It has a wide field of view and a well-corrected optical formula.

The pros

  • Wide-angle, sensibly sized F1.4
  • Coverage of the full-frame sensor
  • Quiet, snappy autofocus
  • On-barrel and aperture ring controls
  • Astrophotography-optimized optics
  • Protection against dust, fluorine, and splash

Cons

  • Focus on breathing in exhibits
  • For Airpeak drones and gimbals, a little heavier

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Sigma 20mm F1.4 DG DN Art Specs

Name Value
Dimensions 3.5 by 4.5 inches
Weight 1.4 lb
Filter Thread 82 mm
Mount Leica L, Sony E
Focal Length (Wide) 20 mm
Optical Stabilization None
Focus Type Autofocus

Sigma has released several I Series Contemporary lenses in a row. Now, the premium Art lens series is back with the F1.4 DG DN Art (20mm) for L-Mount Alliance or Sony E-Mount mirrorless cameras systems. Although the lens weighs more than the compact Sigma 20mm DG DN Contemporary (699), the F1.4 optical formula makes it a desirable choice for photographers, including astrophotographers who work in low light environments. The lens is fully sealed against the elements, and has many physical controls on the barrel. The Sigma 20mm art is a great option if you are looking for a broad-angle, ultra-bright prime. It has been awarded Editor's Choice.

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Broad and bright Prime with Art Series Credentials

Sigma divides its lenses into three categories: Art, Sports, and Contemporary. Contemporary lenses are more portable and affordable, with the exception of the 20mm F1.4 DG DN Art lens. Both lineups include wide primes. Sigma's Sports line does not include wide lenses. This is for long telephotos that have fast focus motors.

The 20mm DG DN F1.4 Art is a hefty lens at about 4.5 by 3.5 inches (HD) and 1.4 pounds. It sports a big front element that takes 82mm threaded filters, though you can also use rear filters. It's not huge by SLR standards—the Sigma 20mm DG HSM F1.4 Art for SLR cameras measures 5.1 by 3.6 inches, weighs 2.1 pounds, and requires an adapter to use with mirrorless cameras, for comparison.

We're not surprised that the older lens for SLRs is bigger, as it's much more complicated to make a bright, wide-angle lens when a mirror box eats up real estate between the sensor and the lens mount. Mirrorless cameras, on the other hand, generally allow optical engineers to design smaller lenses because the rear lens elements can sit mere millimeters away from the sensor plane. In practice, that leads to more compact options with the same angle of view and still-bright apertures, such as the Sony FE 20mm F1.8 G (3.3 by 2.9 inches, 13.2 ounces) and Sigma 20mm F2 DG DN Contemporary (2.9 by 2.8 inches, 13.1 ounces).

The Sigma lens, despite all of these design enhancements, is still very large. It covers a full frame sensor and opens up to F1.4. This requires a lot of heavy glass in the barrel. Sigma's construction uses light materials such as aluminum and polycarbonate, but that doesn't change the laws of physics. At this view angle, we don't think most photographers will need an F1.4 lens. This lens is ideal if you love to capture beauty in dark corners, the night sky, or soft backgrounds.

Sony's competing FE 20mm F1.8 G also features weather protection, and matches well with the company's weather-protected full-frame camera bodies. The Sigma 20mm F2 DG DN Contemporary isn't made for rainy skies, as it only includes sealing at the lens mount. The 20mm F1.4's weather protection is a differentiating factor for L-Mount system owners, as it is the only fully sealed bright prime available—neither Leica nor Panasonic currently offer a 20mm or 21mm L-Mount prime.

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Controls and Focus

The 20mm F1.4 Art offers lots of on-barrel controls, which we appreciate. Most prominent is the manual focus ring, which wraps around the lens body and sports standard rubberized ridges that help with grip.

The Sony E lens was tested along with the a7R IV. Manual focus with this combination is nonlinear. This means that you can make more drastic focus shifts if you quickly turn the ring, but more precise, deliberate adjustments if you spin it slower.

Nonlinear focus is preferred by photographers for its flexibility, while videographers may find it annoying not to be able set focus marks on repeatable focus racks. L-mount camera owners have the option to choose between a linear and nonlinear focus response. We prefer the Sony FE20mm F1.8 G to shoot video because of its light weight and linear focus response. This makes it a good choice for gimbals or Airpeak drones.

Sigma 20mm F1.4 DG DN Art sample image, stone building

The focus breathing effect is quite visible, which is another concern for videographers. The angle of view shifts along with focus and, in this case, the lens shows a broader view when you focus close. You can use the lens for most types of video without worry, but it's not the best fit for rack focus shots that shift attention between subjects.

Autofocus is driven by an STM stepping motor. The focus is fast and quiet which makes it a great choice for video. The lens took 0.3 seconds to go from the closest focal distance to the infinity point on the a7R IV. The lag may be noticeable if you are far out of focus when you start. However, the lens is able to keep up in most cases. It takes 0.15 seconds to bring a blurred frame in focus and expose an image. You can switch focus modes using an on-barrel toggle AF/MF.

The lens also includes an aperture ring that can be used to adjust the f stop. You can adjust it from f/1.4 to f/16, in increments of three stops. A toggle switch allows you silent operation without clicking. The second toggle allows you to lock the aperture controls and select the A position. To set the f stop, switch to A by using the controls on the camera body.

Sigma has an on-barrel button function that can be used as an AFON control. You can however customize the function of most cameras' buttons. A Lock toggle disables the manual focal ring and turns off that button. This toggle is useful for nightsky work, when you need to keep the focus locked in while keeping it on the stars.

Sigma 20mm F1.4 DG DN Art sample image, water running over rocks

This 20mm lens should not be mistaken for a macro lens. However, it can focus extremely close to the sensor (just a few inches away from the front element) and is approximately 9.1 inches long. The lens produces good results at 1:6.1 and is capable of creating dramatic shots with stunning backgrounds. If you like the idea of a wide prime for macro work, don't forget the very affordable Tamron 20mm F2.8 1:2 Macro—it's very sharp and affordable, though it doesn't focus very quickly. The Sony FE20mm F1.8 G also has 1:4.5 magnification.

Sigma 20mm F1.4 DG DN Art sample image, moth on leaf

20mm F1.4 DG DN Art: In the Lab and Under Night Skies

To test the resolution of the 20mm F1.4 DG DN Art lens, I paired it with the 60MP Sony a7R III. Imatest (Opens in new window) evaluates the SFRplus test charts and finds that the lens is nearly perfect. Even at f/1.4, we see excellent results for the sensor of the a7R IV.

Sigma 20mm F1.4 DG DN Art sample image, suburban home

Wide-open, the 20mm F1.4 shows 4,900 lines through most of the frame, with edges that still show very good contrast (4,200 lines). This is a difference-maker for photographers shooting night sky images—you can expect clear results without stopping down the lens. Astrophotography is one discipline where edge-to-edge results at the widest aperture are a practical desire.

My home is too dark to capture Milky Way images that pop. I am not an avid astrophotographer. My starry night images show precise stars and confirm Sigma's claim of an optical formula to suppress sagittal compa. The on-barrel lock keeps the focus in place no matter how you move the focus ring. Also, the flared barrel design prevents lens heating wraps (Opens in new window). These are features that astro professionals use to keep fogging and condensation from entering the frame.

Sigma 20mm F1.4 DG DN Art sample image, night sky

I was happy with my astro shots from a technical perspective, but if you're a dedicated astrophotographer, I recommend reading reviews from specialists to ensure the 20mm F1.4 is up to your standards. The 20mm is not Sigma's only astro lens; if you prefer a slightly tighter angle, the 24mm F1.4 DG DN Art is also marketed for astro work, but didn't do as good a job suppressing sagittal coma in our tests. Sony also sells the FE 14mm F1.4 GM, which nets an even wider view and effectively suppresses coma, but costs much more at $1,599.

Sigma 20mm F1.4 DG DN Art sample image, night sky

With more typical f/1.4 use cases, the edges will blur. Landscape photographers tend to work at narrower settings, for instance, and, at f/5.6 through f/8, results are outstanding from center to edge. With the high-pixel a7R IV, diffraction cuts into detail at f/11 through f/16, though you may still want to use those settings to get the sunstar effect. An 11-blade aperture makes for 22-point starbursts, an uncommon look. The sunstars I got from the lens show slightly mushy lines though—we recommend the Sony FE 20mm F1.8 G's sunstars for landscape photographers who chase the effect.

Although wide lenses don't have the strength to create bokeh well, it is possible with this lens to get blurred backgrounds. As long as the background and subject are at least a distance away, the lens will work. The blurred background looks great! We like the way the defocused highlights look. They are soft and round with no edges.

Sigma 20mm F1.4 DG DN Art sample image, street scene with sunstar

Some optical imperfections, such as visible barrel distortion, can be corrected in-camera. You don't need to be concerned if you are using JPG mode. However, we anticipate that many users of this lens and especially astrophotographers will use a raw processing tool. Sigma provided us with a Raw correction profile to use with the lens in Adobe Lightroom—it effectively removes distortion and compensates for a vignette cast at f/1.4.

Chromatic aberrations do not pose a problem. I couldn't spot any lateral CA in test shots—this effect shows up as purple fringing around dark objects against bright skies and is easy to spot around telephone wires and tree branches when present in a photo.

Sigma 20mm F1.4 DG DN Art sample image, lock and chain link fence

LoCa, a longeritudinal color aberration (or LoCa), is a distinct effect that tends to manifest as false purple or green colors in the blurred focus transition zones. This effect is well suppressed by the 20mm F1.4, but it's not entirely absent. To see the Master Lock logo and padlock detail, I needed to increase the magnification to 200%. However, it's not likely to cause any major problems in real-world situations.

This is a standout among Wide-Angle Specialists

Sigma 20mm F1.4 DG DN Art sample image, butterfly on flower

We typically think of a full-frame 20mm lens as a specialty item. The angle is a bit too vast to use as an everyday prime, with most people opting for either a 24mm or 28mm lens instead. But wide lenses are better for landscapes and architecture work, as well as (and especially in the case of the 20mm F1.4 DG DN Art) astrophotography. The latter discipline screams for vast vistas and bright optics.

Although we couldn't stress-test the lens for Astro work, it was capable of capturing night skies shots. The Sigma 20mm DG DN art is a general-purpose lens that performs better than competitors such as the Sony FE20mm F1.8G. It has sharper and brighter optics, strong on-barrel control, and is more weather-resistant. It's half a pound lighter than the Sony FE 20mm, which means it is more suitable for hiking and vlogging on a gimbal.

Sigma 20mm F1.4 DG DN Art sample image, rocks and water

Tamron's 20mm F2.8 1:2M is an affordable alternative for E-mount photographers for $250. But it's not nearly as competent in dim light and videographers won't like its loud autofocus operations. Don't sleep on it if you're on a tight budget and don't need an F1.4 aperture, though.

Using an L-mount camera makes the decision much easier. Sigma's F2 DG DN Contemporary (20mm) lens is the only autofocusing option. It costs just $699. Although the 20mm Contemporary lens is part of the Metal-Barrel I Series, it has some advantages, such as price and portability. However, its F2 optics capture half as much light as the F1.4, and aren't as resistant to the elements.

For either system, the Sigma 20mm F1.4 DG DN Art is an easy pick for our Editors Choice award. You can't argue with its price, optical quality, or focus performance, and the weather protection makes it a strong fit for outdoor work. You might prefer a lighter lens like the aforementioned Sony 20mm F1.8 or Sigma F2 Contemporary, but neither opens to F1.4, which could be a deciding factor depending on your needs.

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