Zooming? The iPhone X needs just a quarter of the 7 Plus light to do it
Ever since Apple introduced its first dual-camera phone, the 7 Plus, it has been giving us a cropped version of the wide-angle camera at the touted 2x magnification when the light is dim, as the telephoto lens has narrower aperture, and a zoomed-in picture with it just wouldn't come out as good.
The amount of light needed for the telephoto to get engaged in an "optically" zoomed photos is decided by the camera algorithms, and varies with each situation, so a photog decided to measure if there is any difference between the 7 Plus, and Apple's latest and greatest iPhone X. That one has a more capable sensor/lens combo, and more image processing power to get advantage of it, so the "cropped" zoom shouldn't appear as often as it does with a 7 Plus, right?
Well, correct, the setup of studio lighting that was used revealed that the camera of the iPhone X needs roughly a quarter of the light that the iPhone 7 Plus required for the telephoto zoom to kick in - 16 lux vs 88 lux - or about two light stops less, as photographers would say. This means that you will rarely see a cropped image of the wide-angle cam, instead of a true telephoto zoom in low light with the iPhone X, proving its camera more useful when you are out at night, and when you want to get closer to a subject without stepping forward.
source: Studio Neat