The pictures below illustrate the 50mm F1.4 Art's angle of view on full frame and APS-C, taken from our standard position. As is Sigma's way, the lens is just slightly 'wide' for a 50mm prime (its measured focal length is 48mm), bringing it closer to a classic 'normal' view on full frame. On APS-C cameras it behaves like a short telephoto lens. Most prime lenses heavily vignette when shot wide open, especially on a full-frame body. As expected, the Sigma 50mm f/1.4 Art lens vignettes a bit wide open, with vignetting levels falling sharply when stopped down. Vignetting levels vary by focus distance – at close focus the lens vignettes much less than at infinity, as measured by Imatest: When shot wide open, the center of the lens is quite sharp. And the corners, while still very good, are a bit soft in comparison. So when I first found out that Sigma had plans to update its existing Sigma 50mm f/1.4 EX DG HSM, I got really excited, since I knew that the new Art-series lens would not disappoint. It has been too long since both Nikon and Canon updated their 50mm f/1.4 primes. In the case with Nikon, its newer 50mm f/1.8G yields better sharpness than the bigger and heavier 50mm f/1.4G. In short, the Nikkor 50mm f/1.4G is just not good enough for modern high-resolution sensors and its performance at maximum aperture is rather disappointing (and the Canon 50mm f/1.4 is quite similar in that regard). The Sigma 50mm f/1.4 Art announcement was very timely because it hits a sweet spot between the sub-par 50mm f/1.4 Nikon and Canon lenses, and the exotic manual focus Zeiss Otus 55mm f/1.4. Canon EOS 6D + 50mm @ 50mm, ISO 100, 1/800, f/1.6 The Sigma 50mm f/1.4 DG has fantastic optics — but its mechanics and potential for future camera incompatibility are why you pay less for Sigma than for a professional Nikon or Canon lens.

It's super sharp at every setting clear out to the corners, although just a little less sharp in the corners at f/1.4 due to a little bit of coma. It's very sharp in the corners at f/1.4, just quite not as sharp as at the center. This lens is a pain compared to Nikon or Canon's f/1.4 or f/1.2 lenses; this Sigma is too darn big and heavy to actually want to carry it around all day. As far as sharpness is concerned, this lens puts in an excellent performance, especially in the centre of the frame. At f/1.4, sharpness in the centre is already outstanding, although clarity towards the edges of the frame lags behind somewhat. Sharpness towards the edges of the frame improves as the aperture is stopped down, reaching very good levels by f/2.8 and outstanding levels by f/4.

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If you are using this lens on a cropped APS-C-sensor DSLR, then it becomes a great 75mm (equivalent) portrait lens, and by using only the very centre of the image circle, the edge-to-edge sharpness becomes even greater still. The Nikon version should work perfectly on every digital Nikon ever made, both FX and DX, from the best Df, D4s, D810 and D610 to Nikon's cheapest digitals like the D40, D40x, D60, D3000, D3100, D3200, D3300, D5000, D5100, D5200 and D5300. As the version of the lens that I tested was the Canon mount, it seems best to mention the three options that Canon offers as alternatives: The Sigma 50mm f/1.4 EX DG HSM is built similar to current Nikon prime lenses – it has a solid plastic exterior and a metal mount. The lens feels very solid in hands and its large size and heavy weight make it feel like handling the Nikon 24mm f/1.4G. It is almost twice heavier than the Nikon 50mm f/1.8G, which is only 280 grams, and almost three times heavier than the Nikon 50mm f/1.8G (185 grams). The 77mm filter thread is a little too big for a 50mm lens in my opinion, because 77mm filters are expensive. Those who use 77mm filters like polarizing filter will probably be happy about not having to use a step-up ring, but such filters typically get rarely used on 50mm lenses in first place. There is, however, an advantage to having such large front element – as you will see in image samples below, it helps in reducing vignetting at large apertures. Here is how the Sigma compares to other Nikkor lenses (From left to right: Nikon 50mm f/1.8D, Nikon 50mm f/1.8G, Nikon 50mm f/1.4D, Nikon 50mm f/1.4G and Sigma 50mm f/1.4 EX DG HSM): NIKON D3S + 24-70mm f/2.8 @ 70mm, ISO 400, 1/80, f/5.6

The bokeh rendering capability of the lens is quite pleasing for a 50mm prime. Highlight shapes do show defined transitions, but they do not look distracting as on some lenses. The dreaded onion-shaped bokeh that I showed on the Sigma 35mm f/1.4 Art is barely visible when photographing extremely bright points of light. Below are two comparisons that illustrate bokeh rendering capabilities of the following lenses: Sigma 50mm f/1.4 DG HSM Art, Sigma 50mm f/1.4 EX DG HSM, Nikon 50mm f/1.4G and Nikon 58mm f/1.4G. Here is the first comparison that shows bright highlights: What does the Sigma 50mm f/1.4 offer to the already saturated market of excellent 50mm lenses from every DSLR manufacturer? For many years the focal length of 50mm lenses was considered a “standard” or “normal” focal length, because it closely resembles the perspective of the human eye. These lenses were widely popular on film cameras and the focal length was ideal for portraiture and everyday photography. As digital SLRs and zoom lenses started taking over the market, the popularity of 50mm primes also decreased. The smaller size of APS-C sensors made the field of view of 50mm lenses narrower, while the flexibility of zoom lenses and their low price drove the demand towards convenience. Now that full-frame digital cameras are getting more and more affordable, the once-forgotten 50mm lenses are regaining their popularity among many photographers. Seeing this trend, some manufacturers including Nikon have been updating and renewing their 50mm lens lines. Sigma, being a third party lens manufacturer for many brands, introduced their flagship Sigma 50mm f/1.4 EX DG HSM in 2008 and has been marketing it as a higher-quality f/1.4 lens with better characteristics than most branded 50mm f/1.4 lenses. I've greatly exaggerated what little there is by shooting a gray field and presented the images against another gray field: It seems about the same as a common unit-focussed lens, even though it is a unique internally focused design. I see very little coma with this aspherical lens, and what little there is goes away as stopped down.

Rat Palm, 02 September 2014. 36 MP FX Nikon D810, Sigma 50mm f/1.4 DG HSM ART, f/5.6 at 1/125 at ISO 100. Camera-original LARGE BASIC JPG (5 MB; the palm isn't flat so much isn't in focus). Once again, the smoothest of the bunch is the Nikon 58mm f/1.4G, followed by the older Sigma 50mm f/1.4, then the Sigma 50mm f/1.4 Art and the Nikon 50mm f/1.4G. If I had to shoot in the rain, I’d be more comfortable with a Canon EF 50mm f/1.2. It does have that weather-sealing feature. Alternatives Although I am still waiting for the Nikon version of the Sigma 50mm f/1.4 Art to carefully analyze the lens using the high-resolution Nikon D800E, judging from the images I got out of the Canon 6D, I can say that the lens is very sharp wide open at f/1.4 – much sharper than the Nikon 50mm f/1.4G for sure! Center performance is excellent and peaks at the f/4 mark, while the corners start out a little weaker, but get pretty solid when stopped down to f/5.6. You can see lens performance comparisons to Zeiss Otus 55mm f/1.4, the older Sigma 50mm f/1.4, Nikkor 50mm f/1.4G and Nikkor 58mm f/1.4G in the lens comparisons section of the review, while the Imatest figures for the lens are shown below. Canon EOS 6D + 50mm @ 50mm, ISO 100, 1/160, f/1.4 Canon EOS 6D + 50mm @ 50mm, ISO 100, 1/1600, f/2.0 Sigma 50mm f/1.4 Art MTF Performance Imatest detected 0.349% barrel distortion, which is virtually indistinguishable. This low level of distortion should rarely require correction, but if it does, you'll be glad to know the distortion pattern is uniform across the frame.