A few weeks ago, we published a Sigma 24 mm 1.4 Art vs Canon 24 mm f/1.4L II practice test. We then tried out both lenses on a camera with a full-format sensor (Canon 5D MK3) and on a camera with a smaller APS-C sensor (Canon 650D). We noted that Sigma with the 24 mm f/1.4 Art has again delivered a work of art. After we were previously surprised by the extremely good build and image quality of the Sigma 35 mm f/1.4 Art and the Sigma 18-35 mm f/1.8 Art, this was no longer a bolt of lightning out of the blue to us. But it remains a remarkable performance. We are soon publishing a test of the Sigma 24 mm f/1.4 Art on a Canon 5D MK3, but we first want to put up a defense for the quality-conscious photographer who has a camera with an APS-C sensor. Equipped with a good lens, a camera with an APS-C sensor (Canon 70D or Canon 7D MK2) at a focal distance of 24 mm (38 mm full-format equivalent) delivers pictures with a higher image quality than practically all lenses (fixed and zoom) at a focal distance of 35 or 40 mm on a camera with a full-format sensor.
Sigma 24 mm F1.4 DG HSM Art @ Canon 650D
Built and auto focus
The Sigma 24 mm 1.4 Art lens is perfectly finished. It has a wear-resistant metal mount, which, thanks to a special treatment, is extremely precise and durable (although we were not able to test the latter). The lens body is made from TSC (Thermally Stable Composite), which has about the same coefficient of expansion as aluminum. That is important, because practically all lenses consist of both metal (aluminum) and plastic parts. The precision of lenses can decrease with temperature fluctuations if materials with different coefficients of expansion are used. With TSC, Sigma is able to achieve an extremely high degree of mechanical precision. In comparison with polycarbonate, a frequently used material for lens bodies, TSC is more elastic and distorts less. There is 1 switch (AF/MF) on the lens. Built-in image stabilization is missing, just as on practically all wide-angle lenses that are on the market now.
The Sigma 24 mm f/1.4 DG HSM Art consists of 15 elements in 11 groups. Three FLD ('F' Low Dispersion) lens elements and four SLD (Special Low Dispersion) lens elements minimize chromatic aberrations. All that glass does naturally make a lens heavier. At 665 grams, the Sigma lens is about as heavy as the Canon 24 mm f/1.4 L II, but lighter than the Sigma 18-35 mm f/1.8 Art (810 grams). A solid lens bag and a flower-shaped sun cap are included upon purchase.
The HSM (Hyper Sonic Motor) is silent and fast. There is a new 'full-time manual' focusing mechanism built in, with which you switch to manual focusing by simply turning the focus ring, even if the switch on the lens is set to AF. Manual focusing, with a nice, broad focus ring, is nicely dampened and smooth.
Sigma 24 mm f/1.4 Art @ Canon 650D, 100 ISO, f/1.4, 1/125
With a lens with a large diameter, the brightness at the edges of the image area almost always drops off significantly in comparison with the image center. If you do not correct for vignetting, there is practically always noticeable at full aperture with bright lenses—certainly if you use a camera with a full-format sensor. If you use a lens on a camera with an APS-C sensor that is designed for use on a camera with a full-frame sensor, then you've got it made where vignetting is concerned. Even in low light (inside or outside) and if you use the Sigma 24 mm f/1.4 Art at full aperture, then you get contrast-rich shots without visible vignetting.
Distortion Sigma 24 mm 1.4 Art
Distortion, which often occurs with wide-angle lenses, is not corrected by stopping down. The Sigma 24 mm F1.4 Art shows minimal barrel-shaped distortion across the entire image area. It is so low that in practice you will never have trouble with it.
For both bright extreme telephoto lenses and bright wide-angle lenses, there is a complex lens design, where a large number of lenses is used. Every glass-light transition, but also every part of the inside of the lens tube can make a contribution to internal reflections. You see that in your shots in the form of flare (where a bright light source is directly in frame reduces the contrast in a larger area) or ghosts (light flecks, often in the shape of the aperture). With these wide-angle lenses, the use of the sun cap not only provides extra protection for the front lens, you also significantly the chance of ghosts. The Sigma 24 mm f/1.4 Art does its name justice; Sigma has again shown how good they understand the art of minimizing internal reflections. 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 that is just outside frame appear more readily. (I deliberately removed the sun cap in order to get ghosts). For a bright, 24 mm lens, flare and ghosts are well suppressed by the Sigma 24 mm f/1.4 Art.
Sigma 24 mm f/1.4 Art @ Canon 650D, 200 ISO, f/5.6, 1/200
Sigma sets the bar high. And that is also expressed in our measurement results. The sharpness in the center at full aperture is remarkably high for a bright 24 mm lens and reaches the maximum sharpness at f/2.8. The sharpness at the edges and in the corners reaches the highest sharpness at f/4. These are really fabulously good results.
According to Sigma, they minimize lens aberrations with the help of the latest technology and knowledge, and this lens has exceptional rendering and ultra-high sharpness, all the way into the corners of the image. Quality control is strict. The MTF measurement system developed by Sigma uses the 46 megapixel Foveon sensor in order to check each individual Sigma Art 24 mm f/1.4 DG HSM lens before it leaves the factory.
No 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 common with bright lenses ("Ordinary" lateral chromatic aberration, recognizable as red and blue edges at sharp contrast transitions in the corners of the image, are minimized by the lens design. The shots are therefore sharp and rich in contrast.
Bokeh Sigma 24 mm 1.4 Art
Sigma 24 mm f/1.4 Art @ Canon 650D, 100 ISO, f/1.4, 1/250
Next to sensor size, focal distance and the number of aperture lamellae, the quality of the lens elements applied and the rounding of the aperture lamellae may well be even more important for the ultimate quality of the bokeh. There are many lenses—also with a longer focal distance—with aspherical lens elements that deliver a less beautiful bokeh on a camera with a full-frame sensor than the Sigma 24 mm f/1.4 Art on a Canon camera with a smaller APS-C sensor. If you creep up close to your subject, since a 24 mm has a relatively great focal depth, you will be rewarded by the Sigma 24 mm f/1.4 Art with a butter-soft bokeh.
Conclusion Sigma 24 mm 1.4 Art review with Canon 650D
WYSIWYG score: This table shows the performance of this lens if you save the files in the camera as jpg, where you have applied all available in-camera lens corrections. This score gives you for this lens/test camera combination: "What you see is what you get".
Pure RAW score: This table shows the performance of this lens if the file is saved in the camera in RAW format. The score approaches the intrinsic quality of the combination of lens and test camera.
Sigma USB dock and Mount Conversion service options
Usual distortion for a 24 mm
More sensitive to ghosts than the other Sigma Art lenses
Too long, didn't read (TL/DR)? For 900 euros, the Sigma 24 mm f/1.4 Art is a steal.
Anyone who has a camera with an APS-C sensor and is searching for a field of view that approximately corresponds with that of a 35 mm lens on a full-frame sensor absolutely has to look at the Sigma 24 mm f/1.4 Art. Qualitatively seen, every prosumer or ambitious amateur photographer with a Canon camera with an APS-C sensor (Canon 70D, Canon 7D MK2), who loves documentary photography, street photography or landscape photography, should have a Sigma 24 mm f/1.4 Art or a Sigma 18-35 mm f/1.8 Art on their camera. These are the two lenses that we have so far tested on a Canon camera with an APS-C sensor at a focal distance of 24 mm (38 mm converted to full-frame equivalent) at the top in our RAW score lists (chose 35 mm as the FF-equivalent focal distance at which the lenses are tested). These two Sigma lenses deliver visibly higher image quality than number three, the Canon 24 mm f/1.4 L II, which in turn leaves the rest of the competitors far behind. The Sigma 18-35 mm f/1.8 performs on a Canon camera with an APS-C sensor in our tests just as well optically as the Sigma 24 mm f/1.4 Art, offers the advantages of a zoom, but is less bright. That last aspect will be very important to a specific group of photographers. If you photograph under difficult lighting conditions, you love photographing with a fixed focal length or you want to isolate a subject from the background with beautiful bokeh, then the Sigma 24 mm f/1.4 Art is absolutely recommended.
Author: Ivo Freriks
With Camera Review Stuff I hope to make a modest contribution to the pleasure that you get from photography. By testing cameras and lenses in the same way, evluating the results and weighing up the pros and cons, I hope to help you find the right camera or lens.