The Mi 10 Ultra ditched the Mi 10 Pro's 108 MP Samsung sensor in favor of an OmniVision sensor - Why?
Xiaomi released the Mi Note 10 last year, snatching the honor of being the first company to launch a mass-production smartphone with a 108 MP camera. That same sensor went on to be used on the Mi 10 and Mi 10 Pro that were released earlier in the year, but ditched for the new Mi 10 Ultra.
It appears Xiaomi deemed the 108 MP sensor less than ideal. The sensor, the ISOCELL Bright HMX, was heavily marketed as a game-changing CMOS sensor but doesn't seem to have lived up to expectation, hence the switch to the lower-res 48 MP sensor on the Mi 10 Ultra.
In place of Samsung's 108 MP ISOCELL Bright HMX is the new OmniVision 0V48C. As the name implies, it's a 48 MP sensor. While the 108 MP HMX has a 1/1.33-inch physical size, the OV48C is actually slightly bigger at 1/1.32". It also has much fewer pixels, so instead of the 0.8μm pixels on the 108 MP, its pixels are much bigger at 1.2μm. That matches the highly vaunted 50 MP ISOCELL GN1.
Of course, it's easy to see why Xiaomi switched to the OV48C. Cost, for one, as the OV48C is likely a lot cheaper than Samsung's ISOCELL HMX. The 108 MP HMX also had huge issues with autofocus, in addition to extra load on the ISP due to its ultra high-res nature. In any case, the Mi 10 Ultra and its OmniVision sensor appear to perform just fine, so it looks to have been the right decision by Xiaomi.