The Sigma 50mm F1.2 DG DN Art ($1,399) lens is more affordable and compact than Sony's premium FE 50mm F1.2 GM ($1,999.99), and the brightest option for L-mount creators at this focal length. It nets crisp photos at its maximum aperture, uses a fast linear autofocus motor, offers weather protection, and features a complete set of on-barrel controls. The lens isn't flawless, however, as we noticed some false color in images and a bit of texture in defocused highlights. Overall, this Sigma is a fine alternative to the optically outstanding Sony FE 50mm F1.2 GM, though the similarly performing Sigma 50mm F1.4 DG DN Art ($849) keeps our Editors' Choice award for bright, value-minded standard primes on full-frame Sony and L-mount cameras.

An F/1.2 Lens in F/1.4 Clothing

The Sigma 50mm F1.2's maximum aperture is its standout feature since it allows the lens to gather about a third more light than an f/1.4 prime. This technically allows you to get away with slightly shorter shutter speeds or a lower ISO, though those advantages are more academic than practical given how well modern full-frame cameras perform in dim light. The real reason to choose this lens is to get an especially shallow depth of field. If you want the blurriest backgrounds or to match the look of movies like Army of the Dead, this is the f-stop you need.

(Credit: Jim Fisher)

Many f/1.2 lenses are much larger than their f/1.4 counterparts, but that's not the case with this Sigma. At 4.3 by 3.2 inches (HD) and 1.6 pounds, it's not too much bigger overall than Sigma's 50mm F1.4 DG DN Art (4.3 by 3.1 inches, 1.5 pounds) and manages to undercut the Sony FE 50mm F1.2 GM (4.3 by 3.4 inches, 1.7 pounds) in every way. The Sony is already exceptionally small for its class, so this size reduction is a notable feat of engineering. Although Sigma doesn't sell its lenses for Canon R or Nikon Z cameras, it's worth noting that the $2,099.95 Nikkor Z 50mm F1.2 (5.9 by 3.5 inches, 2.4 pounds) and $2,299 Canon RF 50mm F1.2 L (4.3 by 3.5 inches, 2.1 pounds) are both much heftier.

(Credit: Jim Fisher)

As is typical for a Sigma lens, the barrel uses a mix of metal and composite, as well as has a black finish. The included hood is reversible and easy to attach or remove thanks to its bayonet mount and push-button lock. The lens incorporates dust and splash protection for use in rough weather, while the front element has a protective anti-smudge fluorine coating. The front element accepts 72mm filters, the same size as the Sigma 50mm F1.4 DG DN Art and Sony FE 50mm F1.2 GM.

(Credit: Jim Fisher)

Sigma makes the 50mm F1.2 Art for both the E-Mount (the version I tested) and L-mount platforms. Aside from the FE 50mm F1.2 and the Sigma 50mm F1.4 Art on the former mount, you can alternatively get the lighter, slightly more affordable FE 50mm F1.4 GM ($1,299.99). If you don't mind a smaller f-stop, there are loads of 50mm f/1.8 and f/2.0 primes available too, including the top-notch Sigma 50mm F2 Contemporary ($639) and Sony FE 50mm F2.5 G ($599.99) for far less money.

For the L-mount, any Sigma lens is an option, as are autofocusing lenses from Leica and Panasonic. This Sigma is the only 50mm F1.2 available, though the Panasonic Lumix S Pro 50mm F1.4 ($1,799) and Leica Summilux-SL 50mm F1.4 ASPH. ($6,595) are still brighter than most. Both cost and weigh more, however. If you want to spend and carry less, the Lumix 50mm F1.8 ($449.99) and the aforementioned Sigma 50mm F2 Contemporary are worthy choices. Finally, if you want an extra-bright prime with a wider angle of view, check out the bulkier Sigma 35mm F1.2 DG DN Art ($1,499).

(Credit: Jim Fisher)

Smooth Operations and Quick Autofocus

The 50mm F1.2 DG DN Art includes several on-lens controls, as is standard for enthusiast and pro lenses. The barrel includes a discrete ring to set the aperture, along with a configurable function button and an AF/MF toggle switch. The aperture ring can turn from f/1.2-16 with third-stop clicks or silently depending on your preference (an on-barrel switch lets you switch between them). It also includes an A position to move control to the camera body (an additional toggle prevents the ring from moving between the A setting and manual range).

(Credit: Jim Fisher)

A snappy High-response Linear Actuator (HLA) motor handles autofocus operations. The Sony a7R IV camera I used in testing is a step behind the latest in autofocus acumen, but the lens still focuses from near to far in a split second. Just keep in mind that Sony limits the maximum continuous focus drive speed to 15fps for all third-party lenses. If you own a body that supports 20fps or faster drive, like the a1 or the a9 III, you need to buy one of Sony's lenses instead. L-mount cameras have no such restrictions.

I observe some focus breathing, though not as much as you might expect given the extra-wide aperture. Sigma attributes this minimized effect to an optical formula that uses two focusing groups instead of one. There's a visible change in the angle of view when you rack from the nearest focus distance to the furthest, though it's not too much to distract from takes that don't span the entire focusing range of the lens, and if you're using a very wide aperture the shallow depth of field works to mask the effect. If you have a Sony a7 IV or newer model, you can take advantage of focus breathing compensation with optics like Sony's own FE 50mm F1.2 or FE 50mm F1.4 GM, though not with any third-party lenses like this Sigma.

The minimal breathing effect is good news for vloggers who rely on autofocus, and the manual focus experience is equally enjoyable for cinematographers who prefer that operation. The focus ring is properly dampened, has a linear response curve, and offers about 180 degrees of throw from close to far. These aspects combine to provide smooth, precise focus for both videos and photos. If you're working on a careful f/1.2 composition for which the exact point of focus is key, the lens won't let you down.

(Credit: Jim Fisher)

Close-up focus is in line with other fast 50mm primes, which is to say it's just fine. The 50mm F1.2 locks onto subjects as near as 15.8 inches away from the sensor plane. That effective working distance of roughly a foot nets you 1:6.2 life-size reproductions. The Sigma 50mm F1.4 Art (1:6.8), Sony FE 50mm F1.4 GM (1:6.3), and FE 50mm F1.2 GM (1:5.8) all perform similarly here. A fast 50mm is a fine choice for classic macro subjects like flowers, but you won't have as much creative freedom to lean in and find the smallest details or photograph subjects like insects and jewelry as you would with a dedicated macro. The Sony FE 50mm F2.8 Macro and Sigma 105mm F2.8 Macro are better picks for that type of work since both support life-size 1:1 reproduction.

Remember that depth of field is almost non-existent at short subject distances with a wide aperture. I needed to stop down to about f/2.8 to get the entirety of a large blue poppy flower in focus in testing, though you can certainly use blur for artistic effect. Needless to say, the lens blurs backgrounds readily at f/1.2.

(Credit: Jim Fisher)

An extra shallow depth of field isn't the only tricky aspect of using the 50mm F1.2 Art. On bright days, you also need to keep your shutter speed very short or add a neutral density (ND) filter to cut incoming light. I ran into this issue when I left my ND filter on the table before going out for pictures with the lens and had to drop my a7R IV down into its lower extended ISO range to prevent blown highlights for outdoor photos. If you're more about video, using ND is simply a fact of life given that moving pictures call for slower shutter speeds to sidestep jittery rendering of subjects in motion. Without an ND filter, I had a hard time keeping exposures proper at my camera's fastest 1/8,000-second speed with a wide-open aperture.

(Credit: Jim Fisher)

Stabilization is a feature of this lens, which isn't surprising. Most compatible cameras have in-body stabilization anyway. For reference, I was able to consistently get handheld photos free of shake-induced blur at 1/8-second with the lens on the a7R IV, hit-or-miss results at 1/4-second, and motion-blurred photos at 1/2-second. What you can expect in this regard depends on how steadily you can hold a camera, however, so your results might differ.

Sigma 50mm F1.2 Art: In the Lab

I used the a7R IV and Imatest software to check the 50mm F1.2's contrast. The pair put up outstanding numbers with wide-open results above the 5,000-line mark toward the center and an excellent center-weighted average of 4,900 lines. Detail is a little stronger from f1.4-2 (5,100-5,200 lines) and superb for the a7R IV's sensor from f/2.8-8 (5,500 lines). Diffraction sets in and cuts into detail at very small f-stops, but the lens is still fantastic at f/11 (5,100 lines) and pretty good at the minimum f/16 setting (4,200 lines).

(Credit: Jim Fisher)

Although the big selling point here is the extra-bright optics, you still need to use narrower f-stops for scenes in which you want deep focus or for landscapes in which you want to draw bright points of light with multi-point bursts, also called sunstars. The 50mm F1.2's sunstars look clear, though their tines just aren't sharp. Bright standard primes don't generally render crisp starbursts, an effect that's more achievable with zooms and wider-angle lenses.

(Credit: Jim Fisher)

Flare is always a concern for lenses with big f-stops, but the 50mm F1.2 Art does a good job of holding contrast against a bright backlight. I took several images into the sun and observed strong contrast across the plane of focus at the maximum aperture. That said, ghosts (green blobs that result from light bouncing around the inside of the lens) are visible if you stop down the aperture a bit. I noticed them starting at f/4, so it's better to open up the aperture or shift your camera angle slightly if you see them.

(Credit: Jim Fisher)

The lens doesn't show much in the way of distortion, just a slight inward curve for uncorrected Raw photos and none for JPGs. Likewise, I see only a soft vignette in the corners at f/1.2-2 with uncorrected Raws and no trace of it in JPGs. Sigma provided me an early look at its Adobe Lightroom profile that effectively takes care of both without any ill effects on picture quality, so neither effect is an issue.

(Credit: Jim Fisher)

False color is a real problem, however, since the lens shows green and purple color shifts in some instances. I noticed the effect in tree branches just behind the plane of focus at the widest f-stops (f/1.2-1.4), as well as from f/1.2-2.8 for scenarios in which the sun caused specular highlights on the surface of water. This type of false color is tough to remove with software, so it's something to mull if it bothers you and you tend to take images prone to this issue.

Specular highlights also show the onion skin effect, another situational concern. The effect doesn't pop up in every background, but if you've got Edison or string lights behind your portrait subject, you can spot the texture. As for the shape of highlights, I see some cat's eye towards the corners at f/1.2-1.4, though the 13-blade aperture draws rounded bokeh balls from f/2 onward. The Sony FE 50mm F1.2 and F1.4 GM also show cat's eye at the edges wide open, but draw backgrounds free of false texture and better suppress false color. The Sigma F1.4 DG DN Art draws backgrounds similar to the Sigma F1.2, though I can look past that a bit easier given its lower cost.

(Credit: Jim Fisher)

An Affordable F1.2 With Few Flaws

In the manual focus SLR days, f/1.2 primes were desirable because their bright optics made focusing easier in dim light, but they were seldom sharp wide open. Modern mirrorless cameras make lenses like the Sigma 50mm F1.2 DG DN Art possible—it's tack sharp at its maximum aperture, focuses quickly, doesn't weigh too much, and comes in at a reasonable price. The lens is an excellent value overall, though its tendency to draw bokeh with false color in some scenarios prevents it from earning our Editors' Choice award. That honor remains with Sigma's value-minded 50mm F1.4 DG DN Art, which performs just as well on Sony and L-mount bodies and blurs backgrounds nearly as readily. If you use a Sony camera and simply want the best that money can get, however, the Sony FE 50mm F1.2 GM offers nearly flawless optical performance.