With the introduction of the Sigma 24 mm 1.4 Art, Sigma indicated that this was a lens with the highest optical performance in its class—the perfect lens for all kinds of subjects, from landscape to a starry night sky. Given the high quality of the previous bright Sigma Art fixed-focal point lenses (Sigma 35 mm f/1.4 Art and Sigma 50 mm 1.4 Art), coupled with a clearly attractive price tag (a suggested retail price under a thousand euros), the expectations are high.
Would Sigma succeed in meeting them?

Sigma 24 mm F1.4 DG HSM Art @ Canon 5D MK3

Build and auto focus

Sigma makes everything, from the molds to the smallest parts, in Japan. The Sigma Art line is designed with the emphasis on perfect optical performance and a (I quote Sigma) “rich expressive power.” Thanks to an optimized AF algorithm, the AF works more smoothly. The HSM (Hyper Sonic Motor) is fast and quiet. And there is a new “full-time manual” focus mechanism built in, with which you switch to manual focus by turning the focus ring. Simple as that.

With wide-angle lenses, there is often a sagittal coma. With this, point light sources in the corners are not shown as a point, but with a “tail” (coma). Certainly when photographing a starry sky, coma is very disruptive. The Sigma Art 24 mm F1.4 DG HSM has an optimized optical design with an aspherical element in the back that adjusts the approach angle of the light rays, so that the even at the largest aperture, the rendering is outstanding.

The lens has a wear-resistant metal mount, which, thanks to a special treatment, is extremely precise and durable. The lens body is made from TSC (Thermally Stabile Composite), which has about the same coefficient of expansion as aluminum. In comparison with polycarbonate, a commonly used material for lens bodies, TSC is more elastic and distorts less, so that an extremely high degree of mechanical precision is possible.

The Sigma 24 mm f/1.4 DG HSM Art consists of 15 elements in 11 groups. Three FLD (‘F’ Low Dispersion) elements and four SLD (Special Low Dispersion) elements should combat chromatic aberration. Sigma says that they also minimize the skew that occurs with wide-angle lenses. The Sigma 24 mm f/1.4 Art is delivered with Sigma, Canon and Nikon mounts. The Canon mount is already available. A solid lens bag and a flower-shaped sun cap are included upon purchase.

Vignetting

With wide-angle lenses, the brightness at the edges is almost always decreased in comparison with the center. That also applies for the Sigma 24 mm f/1.4 Art. The measurement results seem to be worse than what you see in the practice shots. The vignetting is lower than for the Canon 24 mm f/1.4 L II, but will be recognizable at f/2.8 or greater in practice shots with an even, flat (clear blue or gray sky). Vignetting is a weak point with the use of lenses on a camera with a large sensor, and the Sigma 24 mm f/1.4 Art doesn’t escape it.

Sigma 24 mm f/1.4 Art @ Canon 5D MK3, 100 ISO, f/1.4, 1/8000

Distortion Sigma 24 mm 1.4 Art

Distortion is always present with wide-angle lenses, and is not corrected by stopping down. It was therefore crucial for Sigma to ensure minimal distortion during the development phase. The Sigma Art 24 mm F1.4 DG HSM corrects the approach angle of the light rays that come through the front lens, thanks to the placement of an aspherical element at the front and at the back. This set-up really ensures minimal skew across the enter image surface.

Sigma 24 mm f/1.4 Art @ Canon 5D MK3, 100 ISO, f/16, 1/160

Flare

The Sigma 24 mm f/1.4 Art does justice to its name; Sigma again shows how good they understand the art of minimizing internal reflections.

Both for bright extreme telephoto lenses and for bright wide-angle lenses, there is a complex lens design, where a large number of lens elements is applied. Every glass-light transition, but also ever part of the inside of the lens tube, can contribute to internal reflections. You see those in your photo in the form of flare (where a bright light source that is directly in frame reduced the contrast in a larger area) or ghosts (light spots). With wide-angle lenses, the use of a sun cap not only protects the front lens, it also clearly reduces the chance of ghosts.
In comparison with the Sigma 50 mm f/1.4 Art, ghosts, like the green point in the illustration below that is caused by the bright sun just outside the frame is sooner visible. (I deliberately did not use the sun cap in order to get a ghost.) For a bright, 24-mm lens, flare and ghosts are very well suppressed by the Sigma 24 mm f/1.4 Art.  

Sharpness

Short summary: With this wide-angle lens, you will make fantastically sharp pictures starting at f/1.4.

The center sharpness at full aperture is already exceptionally high, but it increases even further up to f/2.8. At full aperture, the sharpness at the edges and in the corners is exceptionally high for a bright wide-angle lens, but you do see a difference from the center sharpness. That disappears after stopping down a couple of stops.

Sigma 24 mm f/1.4 Art @ Canon 5D MK3, 100 ISO, f/1.4, 1/160

Chromatic aberration

Three FLD (‘F’ Low Dispersion) elements and four SLD (Special Low Dispersion) elements should combat chromatic aberrations. In particular, longitudinal chromatic aberration, which is difficult to correct with software, is commonly seen with bright lenses (“Ordinary” lateral chromatic aberration, recognizable by red and blue edges at sharp contrast transitions in the corners of the image, is also minimized by this lens design. The shots are thus sharp and rich in contrast.

Bokeh Sigma 24 mm 1.4 Art

The aperture has 9 rounded lamellae, which ensures an attractive background blur (bokeh). There is a very small amount of onion ring bokeh visible in the shots of our bokeh test set-up, probably as a result of the application of aspherical lens elements. Bright lenses (<f/2.8) often show color bokeh at full aperture—purple edges in front of the focal point and green edges behind it. Just as with the other Sigma Art lenses, color bokeh is very well suppressed.  

Conclusion Sigma 24 mm 1.4 Art review with Canon 5D MK3

Use the Lens Comparison or look in our list of reviewed lenses to compare this lens with other lenses.

WYSIWYG score: More and more often when designing a lens, distortion, color separation and vignetting are consciously not optimally corrected. As a result, fewer expensive lens elements or exotic glass types need to be used, which ultimately results in a more attractive selling price. The lens manufacturer relies on automatic correction of these characteristics in the camera or in photo editing software. The “jpg-score” gives you for a lens/test camera combination, “What you see is what you get” when all available lens corrections are applied in the camera. 

Pure RAW score: With more expensive lenses, a manufacturer often goes to great lengths in the lens design to prevent lens errors. Neither costs nor effort are spared, which can be recognized by the use of exotic types of glass and many lens elements. The “RAW score” approximates the intrinsic quality of the combination of lens and test camera, with CameraStuffReview attempting to bypass any automatic lens corrections of RAW files. If you use lens correction profiles in Photoshop or Lightroom to convert RAW files, the RAW scores for distortion, vignetting and chromatic aberration will be higher or equal to the corresponding jpg scores.

Pros

• Sublime build and image quality
• Remarkably high center sharpness at full aperture
• Extremely little color bokeh
• Fantastic price-to-quality ratio
• Sigma USB dock and Mount Conversion service available
• Did we mention the sublime build and image quality? Again!

Cons

• Usual distortion for a 24 mm
• Visible vignetting
• More sensitive to ghosts than the other Sigma Art lenses

Too long, didn’t read (TL/DR)? The measurement results confirm the practical experience (or the other way round): the Sigma 24 mm f/1.4 Art beats out the much more expensive Canon 24 mm f/1.4 L II also when it comes to image quality.

The Sigma 24 mm f/1.4 Art delivers an outstanding performance, since the Canon 24 mm f/1.4 L II is a wide-angle lens that scores highly in our list of reviews. At f/5.6, I could not find any differences in image quality between the two lenses, but at full aperture, the Sigma is clearly sharper. The Sigma 24 mm Art also appears to have less trouble with flare and ghosts. As far as image quality is concerned, it is true for both: built like a tank. And vignetting –on a camera with a full-frame sensor—is the Achilles’ heel for both lenses. That can be corrected with software, if you feel it’s needed.

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