Sigma 14mm f/1.4 DG DN Art Review

Focusing Characteristics

The Sigma 14mm f/1.4 Art autofocuses quickly and very quietly, with impressive accuracy both in the viewfinder and in live view. The accuracy was high even in a lab environment which magnifies small focusing errors. I found that it was on par with any name-brand lens when autofocusing on the Sony a7R V. (Autofocusing on the Nikon Z8 with the Megadap adapter was more of a mixed bag, but that is typical of adapted lenses.)

Because of the f/1.4 maximum aperture, the Sigma 14mm f/1.4 Art focuses in very dark conditions without any issue. I even found that I was able to autofocus on the stars at times – although careful manual focus gave me better accuracy and consistency overall. The manual focus ring has plenty of room for careful adjustments, which is ideal when trying to pinpoint focus on a star.

In terms of close focusing capabilities, there are much better choices out there. The Sigma 14mm f/1.4 Art has a maximum magnification of 0.08x (1:12) which is objectively bad, among the worst maximum magnification we’ve seen. At its closest focusing distance, you can fill the frame with a subject that is approximately 43 cm (17 inches) wide, assuming a full-frame sensor.

No big deal – this isn’t meant to be a wide-angle macro lens. Or even a wide-angle pet photography lens. Sigma had one thing in mind when designing the 14mm f/1.4 Art, and that was Milky Way photography.

Distortion

The Sigma 14mm f/1.4 Art has moderately high distortion, measuring -2.83% barrel distortion in our lab tests. This is high enough to need corrections if you’re photographing architecture, or if the horizon is flat in your photo. It’s a tad higher than most 14mm primes, but still less than we see on a typical 14mm zoom.

Here’s a simulation of -2.83% distortion:

Vignetting

In uncorrected images, the Sigma 14mm f/1.4 Art has high levels of vignetting wide open, improving quickly as you stop down. Here’s a full chart of vignetting levels:

The maximum of 2.43 stops is certainly high, but I’m impressed by how quickly the lens gets vignetting under control. At f/2, you’ll get 1.66 stops of vignetting at infinity focus, which is very manageable. By comparison, the Sony 14mm f/1.8 GM measures 2.06 stops of vignetting at f/2 and infinity focus, so the Sigma is about 1/3 stop better.

Normally, we only show vignetting results at maximum aperture and full-stop intervals. However, a lot of Milky Way photographers like to stop down just slightly and would be curious about vignetting at the intermediate apertures. So, I also tested this lens at f/1.6 and f/1.8. At those apertures and infinity focus, it measures 2.16 and 1.87 stops of vignetting respectively.

This is about 1/3 stop better than the Sony 14mm f/1.8 GM, which measures 2.21 stops of vignetting at its maximum aperture of f/1.8.

Lateral Chromatic Aberration

There is a small amount of lateral chromatic aberration on the Sigma 14mm f/1.4 Art, hovering right around the point where it is not even noticeable. Here’s the chart:

Anything under about one pixel is unlikely to need corrections, even on a high-contrast subject. The Sigma 14mm f/1.4 Art is a little higher than that at f/1.4 and f/2, but a little below that mark at each subsequent aperture. This is strong performance for such a complex lens. Chromatic aberration is not a concern.

Sharpness

The Sigma 14mm f/1.4 Art is a sharp lens even at f/1.4. Here’s how it performs in our Imatest measurements:

This is a strong performance that improves steadily as you stop down, with f/4 being the sharpest in the center and f/5.6 being the sharpest in the corners. However, I found myself often stopping down even further when using this lens, since 14mm tends to capture a lot of nearby foreground. Using f/16 is not out of the question even though the lens (like all lenses) loses some sharpness due to diffraction at such a narrow aperture.

The result shown above will be put into context on the next page of this review, but it’s a very sharp lens overall.

In terms of other sharpness issues, there is some meaningful focus shift with this lens, but only at close focusing distances. Thankfully, at infinity focus, I don’t notice any focus shift at all. This means you can safely focus on the stars at f/1.4, stop down to a narrower aperture like f/2 or f/2.8, and still get totally sharp results.

Finally, I saw a bit of traditional-shaped field curvature on the Sigma 14mm f/1.4 Art at the medium apertures (f/4 through f/8), which slightly reduces the corner sharpness at those apertures in the graph above. There is also field curvature at the wider apertures, but with a wavy shape that impacts midframe sharpness more than the corners.

Coma

Related to sharpness is coma, a lens aberration that can make dots of light in the corner of a photo look like smears. Coma isn’t usually visible in everyday photography, but for something like Milky Way photography, it can be a factor. Considering that the whole point of this lens is Milky Way photography, I was eager to put its coma performance to the test.

The crops shown below are taken from the following sections of the image:

I took all the photos in this section at a quick exposure (for Milky Way photography, at least) of six seconds in order to eliminate motion blur. To compensate for the loss of light, I used higher-than-usual ISO values. While this does lead to more noise, the crops below have no star trailing as a result. This allows you to examine the effects of coma and other lens aberrations independently of any motion of the stars.

Test 1: Sigma 14mm f/1.4 Art on Sony a7R V

Let’s look at the center of the image first for reference, then examine the top left corner. Here’s a central crop at f/1.4:

This is already excellent performance. To keep this page manageable in length, I won’t be adding central crops at other apertures – there’s no need, it already looks great wide-open.

The real question is the extreme corner. Here’s how it looks at f/1.4, f/1.8, f/2, and f/2.8:

This is excellent coma performance. It’s not perfect at f/1.4, but still completely usable. It really sharpens up at f/2, and the f/2.8 performance is perfect.

But how does it compare to some alternatives? Namely, I wanted to test the previous generation DSLR lens, the Sigma 14mm f/1.8 Art, as well as the Sony 14mm f/1.8 GM. Here’s how those lenses perform.

Test 2: Sigma 14mm f/1.8 Art on Sony a7R V

The Sigma 14mm f/1.8 Art is an older, DSLR-designed lens that Sigma eventually released in Sony E mount. It’s just as large and heavy as the newer f/1.4 version. Because of that, it’s definitely less practical in today’s world.

However, it still makes for a good comparison because of its long-running popularity among Milky Way photographers. (See our review.) How does it hold up? Here’s a crop from the center of the Sigma 14mm f/1.8 Art, taken wide open at f/1.8:

As with the f/1.4 version, the central performance is excellent even wide-open. Nothing to worry about here at all.

Here are the corners by comparison:

The corners here are clearly worse than they are on the newer Sigma 14mm f/1.4 Art. While they are usable even at f/1.8, the reality is that the f/2.8 performance above is about the same as the f/1.4 performance of the Sigma 14mm f/1.4 Art. The newer version is just that much better.

Test 3: Sony 14mm f/1.8 GM on Sony a7R V

In my review of the Sony 14mm f/1.8 GM, I gave it full marks for its excellent coma performance. How does it compare to the Sigma 14mm f/1.4 Art? First, let’s double check that the center looks good wide-open:

It does indeed! The real question is the extreme corner. Here’s how it looks at f/1.8, f/2, and f/2.8:

The images above speak for themselves, but this is really fantastic coma performance – actually a bit better than what we see on the Sigma 14mm f/1.4 Art. (At least, that’s the case at f/1.8 and f/2. Once you’re stopped down to f/2.8, the two lenses are equivalent.)

I wouldn’t call these differences drastic, but they’re enough for the Sony 14mm f/1.8 GM take the crown among the lenses tested here. That said, you will get about 1/3 stop extra vignetting on the Sony compared to the Sigma 14mm f/1.4 Art at f/1.8 and f/2, so keep that in mind.

Test 4: Sigma 14mm f/1.4 Art on Nikon Z8

Lastly, I was interested to see how well the Sigma 14mm f/1.4 Art adapted to the Nikon Z system. I used Megadap’s Sony-to-Nikon adapter for this test – a hollow adapter that does not have any glass elements of its own.

The following crops are from the same percentage of the frame as above. Since the Nikon Z8 has a 45 megapixel sensor compared to 60 megapixels on the Sony a7R V, these crops are a little lower in resolution. This doesn’t make much of a difference to my takeaways, however.

Here’s the center of the frame at f/1.4:

It’s perfect here, nothing to complain about at all. The central performance is just as good on the Nikon Z8 as it was on the Sony a7R V.

However, the story changes when you look at the far corners:

It’s an interesting result. There isn’t any blurring, but rather than being perfect dots, the stars in the corners are little lines instead. At first, I thought this might be an effect of star trailing, so I took another exposure at 2.5 seconds, but they didn’t change size. I can also rule out an adapter alignment issue – had that been the cause, we would have seen more improvement upon stopping down, and it would have looked like out-of-focus blur rather than lines in the first place.

This isn’t the first time I’ve seen corner-related issues when adapting mirrorless lenses across brands. It was even stronger with the Sony 14mm f/1.8 GM. It’s better to use native glass when possible, so that the lens is being used on the sensor stack it was designed for. (Although adapting DSLR lenses to mirrorless cameras does not cause a similar issue, in my experience.)

Even so, the lines in the corners here certainly could have been worse. I found myself taking plenty of photos with the Sigma 14mm f/1.4 Art and Nikon Z8 combo during my time with this lens, and my pictures were completely usable. But I wouldn’t go out of my way to adapt this lens normally and would rather use Nikon’s 20mm f/1.8 S or 14-24mm f/2.8 S if possible.

Flare and Sunstars

Complex 14mm lenses tend to have a lot of flare, but I was pleasantly surprised to see good performance on the Sigma 14mm f/1.4 Art. Here’s a very typical example:

The one downside is that I would get dots of flare with this lens when the sun was outside the frame. The lens hood definitely does not provide full protection from off-axis light. Here’s an example from the same scene:

As for sunstars, stopping down to f/16 with this lens will give you beautiful and sharp 22-pointed stars, thanks to the lens’s 11-blade aperture diaphragm.

The next page of this review dives into the sharpness numbers a bit more, with some comparisons against other lenses that you may be considering. Click the menu below to go to “Lens Comparisons”: