Xiaomi 12S Ultra review: the camera with the 1-inch sensor

The Xiaomi 12S Ultra boasts a huge image sensor and Leica has a hand in the camera. Reason enough to take lots of photos and assess them.

Until now, Xiaomi had only sold the 12S Ultra in China. But at the end of August, company CEO Lei Jun announced on Twitter that the «next iteration» would be available worldwide. However, he left it open to interpretation whether the «next iteration» meant a global version of the 12S Ultra or an actual successor with a 13 in its name. Nevertheless, Xiaomi had already brought test devices to Germany, and the company gave me one to try out. As I’m curious about how the big sensor works, I was happy to put it through its paces for a few days.

Three cameras and physical limitations

For reference, this is how the parts fit together: the lens in the middle of the round camera element belongs to the wide-angle camera. In landscape format, the narrow-angle camera is on the left and the main camera is above the wide-angle camera.

The specs for the big sensors sound reasonable when you consider it in terms of the fundamental rule that «the bigger the sensor, the better the image quality». Nevertheless, there’s a physical problem. Namely that the bigger the sensor, the further away the lens has to be in order to achieve the angle of view. As my colleague David Lee explains in relation to the Sharp Aquos R6 (article in German), smartphones are too narrow for big sensors like these. Xiaomi states that the focal length on the 12S Ultra’s main camera is 23 mm. That’s a wide-angle focal length, but for smartphones, it’s standard for the main camera. Meanwhile, the wide-angle camera on the 12S Ultra features a 13 mm focal length. And yet, the smartphone isn’t as bulky as a compact camera. Leica and Xiaomi say the way they got around this was by «diverting» the light. As a result, it’s meant to hit the sensor at a wider angle than the distance from the lens actually allows.

Arguably, other manufacturers make do by cutting out image stabilisation or only using the middle area of the sensor. Both of these options just relegate the large sensor to an unnecessary marketing gimmick.

The main camera: a blooming good sensor

The Sony IMX989 on the main camera boasts a 1-inch surface area with a resolution of 50.3 megapixels. Each pixel is 1.6 micrometre. But Xiaomi consolidates four pixels to one as standard. That’s why photos have a resolution of 12.5 megapixels – unless you activate 50 megapixel mode. But there are a lot of tools missing from that. In absolute terms, from the lower resolution range there’s even a pixel length of 3.2 micrometres on the sensor. The focal length amounts to 23 mm – when converted to a 35 mm format – and the aperture opening is f/1.9.

All sample photos were taken in automatic on the Xiaomi 12S Ultra. The smartphone and software dealt with image processing and saved the photos directly as JPEG files. You can only get uncompressed photos in RAW format in pro-mode.

Natural colours and high level of detail

As I have certain expectations of the big sensor, I don’t bore the Xiaomi 12S Ultra with ideal conditions. Instead, I head out into Hamburg’s warehouse district and dockside around sunset.

I like the colour reproduction. It matches what my eyes see live on the spot. The level of detail is very high, but I can’t see the difference compared with other excellent smartphone cameras.

From a negative point of view, what I notice is that 23 mm is too wide an angle for a lot of the subjects. All the more so because I took shots of almost all the subjects using five-times zoom. But more on that later.

Let’s look at the details first. I cropped the middle area in its original size from a photo and then put it next to the shot from the Huawei P50 Pro that I took right after. Overall, the photo from the Leica camera on the P50 Pro is less wide-angled and, as a whole, slightly lighter.

In the cropped section, the colour differences are clearer. The 12S Ultra is my favourite, even though I can’t detect any advantages of the big sensor when it comes to the level of detail.

The level of detail on both cameras wanes the further away the subject is. In the front section, you can pick out the individual stones on the wall more clearly on the 12S Ultra.

Automatic mode does a good job of brightening the shot in the dark. Meanwhile, night mode considerably increases the level of detail in a direct comparison.

But if I look at the images in their original size and compare them with photos taken on the Huawei P50 Pro, the big sensor on the Xiaomi 12S Ultra doesn’t seem to provide any advantages when it comes to level of detail. I put the colour differences down to the different types of software.

Wide-angle and narrow-angle camera: smaller sensors, but still worth mentioning

Both the wide-angle and narrow-angle camera on the Xiaomi 12S Ultra use the half-inch Sony IMX586, which has already been tried and tested in a lot of other smartphones (article in German). It’s the lenses in front of it that create very different angles of view, 13 and 120 mm. Compared with the main camera, they boast smaller apertures – f/2.2 and f/4.1.

When I look at what I’m capturing, I use the narrow-angle camera more often than the wide-angle camera.

Using the narrow-angle camera, I get closer to the sun that’s disappearing behind the building, and I can better draw attention to the harbour police station that’s concealed by the little bridge. All in all, it looks decent and is worthy of top-smartphone status, but there’s nothing that could set the Xiaomi 12S Ultra apart from other excellent smartphone cameras.

The night mode provides improved image quality on both cameras. Images are lighter and characterised by a higher level of detail. The gain in quality is more pronounced with the narrow-angle camera. But all things considered, it’s nothing that other smartphones can’t also manage.

Portrait photos are nicest in black and white

Other smartphones also do a great job of capturing portrait photos with a blurry background. The Xiaomi 12S Ultra provides three presets for this – one of them I like a lot and one of the others seems a bit superfluous.

I like the black and white portraits with a 35 mm focal length. They give off a classic photography feel and slow down any subject.

«Swirly bokeh» at 50 mm seems identical to the standard settings in portrait mode to me. It separates people and the background very well. But that isn’t anything special any more.

The «90 mm soft focus» seems completely unnecessary to me. I don’t see any point in making faces out of focus on purpose, even though «soft focus» sounds intentional.

Leica Authentic and Leica Vibrant

All the photos I’ve shown so far were taken in «Leica Authentic» mode. In «Leica Vibrant», there’s another set of presets to choose from. I have to select one of them, as I can’t deactivate it completely.

The colour difference between them is less noticeable than I’d expected. Vibrant is a bit lighter, which makes it look fractionally more cheerful – especially when you’ve got grey clouds in the sky. But I slightly prefer Authentic, so I mostly used that.

You can find even more filters in the camera app. Four of them also have names linked with Leica. My favourites are the black and white filter «Leica BW Nat» and «Leica BW CH». «Leica Viv» and «Leica Nat» don’t entice me enough to try them out. Incidentally, none of these filters noticeably deactivates Authentic or Vibrant.

Verdict: I’d hoped for more

The Xiaomi 12S Ultra takes great photos. The phone delivers good images especially in tricky lighting. I was also bowled over by the portrait images in black and white. But I’m still a little disappointed. I’d expected the large image sensor to offer more of a difference to current smartphones on the market. However, the comparison with the Huawei P50 Pro shows how good the software is on other smartphones and how little impact the sensor size has on smartphone photos.

In practice, this means I won’t wait longingly for Xiaomi to release the Xiaomi 12S Ultra or its successor on digitec. The theoretical advantages of the large sensor area don’t have enough ramifications in practice.