The rear cameras of the iPhones 7 Plus, 8 Plus and X are very, very similar. In fact, the wide-angle lens, technically speaking, is exactly the same; what changes telephoto and the ability of the A10 Fusion (7 Plus) and A11 Bionic (8 Plus and X) chips to process it all. While in the iPhones 7 Plus and 8 Plus we have a telephoto lens with a /2.8 aperture, the iPhone X has a /2.4 aperture and, in addition, it still has optical stabilization.
In practice, this means that your photos and videos using the second rear camera of the iPhone X are able to capture more light (something very important in low light environments) and come out less shaky (os). We will try to show this in practice in our review of the iPhone X, which will soon be released on the iPhone 8 Plus, you can check it out here.
Last year, when the iPhone 7 Plus was launched, Glenn Fleishman (from Macworld) detailed the operation of the camera system with two lenses. In short, when you touch the 2x zoom button, the camera does not always switch to the telephoto lens. That's because, in low light environments, iOS chooses to digitally zoom using the same wide angle, which has a larger aperture and can capture more light. So, for Apple, it is worth a “cropped” image with reasonable quality than an original with poor quality.
Dan Provost then decided to do a last test comparing the dual camera system of the iPhone 7 Plus with that of the iPhone X. He positioned the two devices very close, focusing on the same object (a Rolleiflex camera). Using LED studio lights, he then increased the light intensity (from dark to light), to see exactly where iPhones automatically switched from wide angle to telephoto.
On the video, it's clear how the iPhone X needs a lot less light (16lx) to automatically switch to the telephoto lens when you're taking a 2x photo, obviously. The iPhone 7 Plus, as we can see, requires a lot more light (88lx). For those curious about planting, lighting was measured with the Light Meter app.
Of course, it's not a fully controlled scientific test, but it gives us a great idea of the iPhone X's telephoto camera capability a big evolution in a year, since such a camera made its debut alongside the wide angle in 2016.
via Daring Fireball