Sony Versus Sigma: Which 50mm f/1.4 Reigns Supreme?

When Sony and Sigma released lenses with nearly identical specifications (or at least nearly identical target customers), photographic gear scheduling marked a rare alignment. Photographically speaking, the concurrent launch of these two similar lenses is the equivalent of a full solar eclipse—incredibly rare and also amazing to see.

The Sony FE 50mm f/1.4 G Master lens and the Sigma 50mm f/1.4 DG DN Art lens represent the pinnacle of both companies’ optical technology. They are also aimed at the high-end portrait, wedding, event, and video customers looking for superb image quality, fast autofocus, and generous background defocus.

On paper, this contest was a slam dunk for Sigma, with an $850 price versus $1,300 for the Sony, as it boasted not only a cheaper price but also similar specs across the board. But comparing products by specs and price alone often needs to include subtle differences between competing products.

For a long time, my lens third-party lens reviews had a phrase like, “it provides 75 percent of the performance of the manufacturer lens for half the price.” That difference remains, but in the comparison of these two lenses, the margin between the two has gotten smaller.

Some people put the dollar figure first while others buy manufacturer lenses over third-party lenses, no matter the price difference.

With the Sigma and the Sony 50mm, the equation becomes closer to, “the Sigma provides 90% of the performance of the Sony lens, but for 65% of the price.” But there’s a catch, that 10 percent difference might be a dealbreaker for some of the target customers.

Head-to-Head Has Changed

Most 50mm wide-aperture lenses are big and heavy. You can make a lens transmissive to light by making the elements larger or by making them with more sophisticated techniques than most lens elements.

If you think of the thick “coke bottle” glasses associated with nerds and geeks in shows about the 1970s and 1980s, that’s using the brute force of using big chunks of glass to modify incoming light.

We see fewer of those big glasses because it’s easier to make optics using advanced manufacturing and engineering to solve the optical problems those chunky glasses solved.

Sigma’s high-end Art lenses have traditionally been large, heavy beasts. One way to make wide-aperture lenses more affordable is to use large lens elements instead of mechanically sophisticated ones. That’s also why the Sigma Art lenses have had slow autofocus; moving big glass requires big motors, and the heavier the glass, the slower it moves.

In most reviews of third-party lenses like Sigma, the large sizes and slow focusing has been the tradeoff for the lower price. Most reviews have discussed how the Art lenses are so big and slow that they produce a beautiful image.

Most reviews of high-end third-party lenses point out that the manufacturer lenses offer similar or better optical quality at a much smaller size and with better AF but at a higher price.

That’s why this new Sony and Sigma head-to-head are so interesting — Sony’s 50mm is shockingly tiny, but Sigma’s 50mm is only a touch larger and heavier.

So, that’s a new twist.

The Lenses: On Paper and In Hand

Looking at the spec sheets, the lenses are remarkably similar, and we have reviewed both the Sony 50mm and the Sigma 50mm. On paper they are nearly identical.

The Sony 50mm has 14 elements in 11 groups, including 2 XA (extreme aspherical) elements and one ED (Extra-low Dispersion) element. Sony says these specialized lenses are designed to reduce aberrations. The company’s Nano AR II coating is also applied to lens elements to minimize flare and ghosting. The Sony FE 50mm f/1.4 GM has 11 aperture blades designed for smooth bokeh.

Meanwhile, the Sigma 50mm has 14 elements in 11 groups, including one SLD (Super Low Dispersion) and three aspherical lenses. It also has an 11-bladed aperture for smooth bokeh.

The Sigma 50mm f/1.4 DG DN Art has Sigma’s Super Multi-Layer Coating to reduce flaring and ghosting and a front-element coating to reduce fingerprints, grease, and dust contamination.

Throughout the rest of this review, I’ve arranged a bit of a comparison of photos taken with both lenses. See if you can guess which one is Lens A and which one is Lens B. I’ll reveal which is which at the bottom of this story. These images are not color corrected or edited, aside from some minor white balance fixes and the images are as straight out of camera as possible.

See if you can spot the differences — lots of high-quality elements, linear motors, 11-blade aperture, and flaring-reducing coatings.

Operation and Images

In general use, it’s almost impossible to tell these lenses apart either. While not much bigger, the Sigma is noticeably heavier in hand than the Sony, but this just about disappears on the camera.

Focusing is also remarkably similar; in some instances, the Sigma seemed to outperform the Sony in certain backlighting situations and the Sony edged out the Sigma in moving subjects. This is hard to say definitively without both cameras side-by-side shooting the identical subject. But usually, there’s a big enough difference between a manufacturer lens and a third-party lens that’s significant.

In my tests, I would swap back and forth between the two lenses between shots and I needed help to tell which lens I was using. I could tell from the feeling of the lens, but if I didn’t hold the lens body while shooting, it was hard to know from the shots.

The Sony lens did seem better at all-around focus. To try to put a number on it, the Sony was 10% better than the Sigma at eye acquisition and similarly better at tracking moving subjects, but that might be generous.

From an image standpoint, the lenses are virtually identical. Since all of my shots were on the same camera body, I loaded them into both Lightroom and Capture One and displayed them without any visible metadata.

I could not tell the difference between the images, except for a slightly different “feeling” bokeh between the two. Neither was better; they just weren’t identical. The softness of the diffused light from windows and lighting elements was subtle but unique.

I didn’t spend as much time shooting videos with these lenses as still images; the 50mm focal length isn’t prevalent in video shooting. Still, I did shoot in-studio YouTube videos with both, and both tracked my eyes consistently and accurately, even wide open. In my few video tests, both pulled focus with repeatable results and tracked subjects well.

Speed Difference and Future Proof

There are two areas where the Sony lens is significantly better than the Sigma: tangible and intangible.

The first is in frame rate. As will all Sony lenses, the 50mm f/1.4 GM can operate at the full 30fps rate of Sony’s fastest cameras. The Sigma is limited to the medium 15fps AF speed. It’s still unclear if this speed limitation is an actual hardware/firmware one or a limitation imposed by Sony to ensure good performance at the high frame rates.

In other words, while Sony opened its mount to other developers, it still has more information about camera focus signals and the electrical connectors than it gives the third-party developers. The 30fps speeds of Sony lenses might be because Sony sends more information across the connectors. After all, its lenses can decode it.

Alternately, Sony limits third-party frame rates because less powerful rotational motors wouldn’t be unable to keep up and would result in many missed frames. This is why Sony’s older lenses can also not shoot at 30fps. It’s possible that since Sony can’t know what third-party lenses are fast enough to hit 30fps, it limits the speed of all third-party lenses.

Of course, it’s also possible that Sony limits the speed of third-party lenses to help the value of its first-party lenses. This feels less likely to me than the other options, but it’s still possible.

The second area where Sony has an advantage in these lenses is related to the first advantage. Because Sony’s camera and lens divisions work together, Sony can future-proof its lens designs.

When and if Sony cameras hit forty frames per second or faster, it’s a good bet all the lenses that support 30fps currently will support that faster frame rate.

Purchase Decisions

At this point, you probably want to know which lens is Lens A and which is Lens B. The answer? Sigma is Lens A and Sony is Lens B. Honestly though, you probably had a hard time telling the difference.

Often in comparisons of high-end lenses, the recommendations are simple, as I mentioned at the beginning. Generally, if you want the fastest performance possible and the best image quality, spend the money on the manufacturer’s lens. If you’d like to save money, but lose some performance, get the third-party lens.

In this case, the answer is more nuanced. With similar specs and image quality, the Sigma is a better deal by a much wider margin than other lenses it has made. If you have no intention of shooting faster than 15fps (portrait shooters, landscape photographers, astro shooters, I’m looking at you), the Sigma is hands-down the better deal.

If you’re shooting sports, fast-moving subjects, wildlife, or any other scene requiring the fastest, most accurate performance, the Sony is your choice. And if you want to ensure your lens is compatible with anything Sony releases in the future, the Sony is a better choice.

Perhaps it’s good here to frame this in Sony’s camera selection. Users of the Sony Alpha 1, Alpha 9, and Alpha 9 II, plus any high-speed camera that comes down the road, should get the Sony lens.

Shooters of the Alpha 7R series, Alpha 7 IV, and earlier would do better with the Sigma.

For video shooters, this might be a more complex decision. With the 50mm focal length being uncommon and the f/1.4 aperture, something used to create a specific-looking shot, I would personally pick the Sony, as I know it will have the best-possible autofocus in video thanks to the collaboration between camera and lens engineers.

But all that said, for the first time in my memory, there are two nearly identical lenses with nearly identical performance. No matter which lens you pick, you’re getting some of the best, most accurate, most detailed images ever possible in photography.