Apple describes the XS as sporting “dual 12MP wide-angle and telephoto cameras”. This will be obvious to most of you, but in case it’s not, they’re not just dual rear-facing lenses, they’re dual rear-facing cameras. The wide-angle and telephoto lenses each have their own sensors. As a user you don’t have to know this, and should never notice it. The iPhone XS telephoto camera is the same as in the iPhone X — same lens, same sensor.
But the iPhone XS wide-angle camera has a new lens, which I believe to be superior to last year’s, and an amazing new sensor which is remarkably better than last year’s. And last year’s was very good.
Anytime an iPhone review gets too technical about camera details and photography lexicon, I tend to gloss over it and move on. I'm not a camera expert and I usually don't care about the nitty-gritty. But John Gruber's analysis of the iPhone XS' camera stack, A12 SoC, and seemingly unadvertised improved sensor is one of the most interesting camera-focused iPhone reviews I've read in years. I don't want to spoil it – move past the photos at the beginning and keep reading.