One-inch sensors have come to photographic mobiles to stay: why don’t they take advantage of them 100%

In digital photography the physical size of the sensor matters. Of great importance. The surface of the collector profoundly conditions its ability to collect light, so if we compare two sensors with the same technology and different sizes, the largest will always get more light. When the circumstances are unfavorable and this resource is scarce, having a large sensor can help us take pictures with less noise and more detail in shadow regions.

Furthermore, if its resolution is adequate and it is not excessive, the photodiodes of a large sensor are also large, which should allow each of them to collect a lot of light and avoid aggressive post-processing that often degrades the naturalness of our photographs. If we stick to smartphones with a photographic vocation, for the moment, their zenith are the one-inch sensors, which, beyond the noise they are making, are not exactly new.

sony, Leica or Sharp are some of the mobile phone manufacturers that have placed terminals in stores equipped with a one-inch sensor in recent years. Last year Xiaomi launched its 12S Ultra, a smartphone equipped with a 50.3-megapixel IMX989 sensor manufactured by Sony that incorporates 1.6 µm photoreceptorsand has just repeated the same move with what is already its new flagship photographic mobile.

A few hours ago, this Chinese brand presented the Xiaomi 13 Pro, which incorporates the same sensor in the main camera. In addition, it has the support of Leica, a veteran and highly respected German camera manufacturer that, according to Xiaomi, has been actively involved in fine-tuning the cameras of this terminal. We have already had the opportunity to analyze it in depth, and, although we have liked it a lot, its arrival has reminded us that getting the most out of a one-inch sensor on a mobile is not easy at all.

Smartphones do not make it easy for one-inch sensors

Before we go any further, and for the purpose of giving some context, it’s worth taking a look at what is probably the most ambitious photography smartphone to hit stores yet: Sony’s Xperia PRO-I. The main camera of this 1,800-euro mobile incorporates a 1-inch, 20-megapixel Exmor RS CMOS sensor with 2.4 µm photoreceptors that works hand in hand with an optic manufactured by ZEISS with a double aperture value (f/2.0 and f/4.0).

These specifications on paper look great. In fact, this terminal looks more like a compact camera disguised as a smartphone than a conventional mobile phone. Despite everything, beyond the advantages of having a sensor with 2.4 µm photoreceptors at our disposal, it has an Achilles heel: the effective resolution of the sensor, the usable one, is 12.2 megapixels, and not 20 megapixels. Those almost 8 “lost” megapixels cannot be used because the optics only manage to cover the central area of ​​the sensor.

Developing high-quality optics for a mobile phone that is bright and manages to minimize chromatic aberrations and geometric distortion is not easy. And it is not, above all, due to the very limited space available inside. Sony engineers could have provided the main camera of the Xperia PRO-I with optics capable of collecting light and projecting it onto the entire surface of the one-inch sensor (this is what they have done in the camera RX100 VII), but in that case this smartphone it would be thicker, heavier, and perhaps also larger. And most of the users would possibly reject such a lump.

Of one thing we can be sure: Xiaomi and Leica engineers have faced this same problem during the development of the new Xiaomi 13 Pro. In fact, my colleague Ricardo, who is the editor of Xataka who has prepared the analysis of This smartphone highlights something that we cannot ignore in its conclusions: shooting in RAW mode only allows us to use 12 megapixels of the sensor, and not the 50.3 megapixels that it really has. Its performance in compromised shooting scenarios is very good, as Ricardo explains, but it’s a pity that this mobile can’t get more out of the RAW sensor.

For us, this is precisely the great outstanding debt of smartphones equipped with a one-inch sensor. It is currently not clear that the miniaturization of traditional linear optics will solve this problem in the short term, but it is possible that periscopic objectives do because they allow a large number of optical elements to be stacked.

And, along the way, they solve the limitations introduced by the little vertical space available inside a mobile phone. We’ll see what happens. Be that as it may, the good news is that photography enthusiasts have at our disposal smartphones as appetizing as Sony’s Xperia PRO-I or the Xiaomi 13 Pro, among other terminals with a marked photographic vocation. The potential of its photographic hardware is beyond doubt, but the most important thing is that it puts juicy creative capabilities in our hands.