Two things that iPhone 11 Pro have on their cameras are a telephoto lens and night mode for night photos. While one expects that when zooming in x2 the telephoto lens is used … this does not happen when the photographs are nighttime. But of course, Apple uses a trick to make it seem so.
One of the advantages of the telephoto lens is that it allows us to take photographs with x2 magnification without losing resolution in the image since it is the lens itself that makes the magnification physically. The problem? This lens has a smaller aperture and its sensor captures much less light than that of the main camera or that of the ultra-wide-angle camera.
In night photography it is precisely where more light needs to be captured, so if we want to zoom at night x2 … if the iPhone acts as it acts during the day (activating the telephoto lens) we would see practically nothing. What does the iPhone do instead? Use the main lens to imply that you use the telephoto lens.
Telephoto lens seems, wide-angle
Basically when we press the x2 zoom in night photos with the iPhone 11 Pro what the iPhone does is to make a digital zoom of the main lens. This means taking the image that the main lens captures, trimming half and enlarging it. A digital zoom of a lifetime. The problem? The resolution with this method is reduced because basically the image is cropped. The solution? The iPhone automatically rescale the image so that it has the same resolution as without digital zoom.
As a result, we have an image that seems to have been taken with the telephoto lens but has actually been taken with the main lens, cropped and modified to look like optical zoom. From PetaPixel they have been able to verify it and you can also do it with something as simple as covering the telephoto lens with your finger while taking a night photograph with x2 zoom. The theory says that you should stop seeing the image since you are covering the lens, but as the main lens is actually used … you can still see the image. On the other hand, if we go to the metadata of the photographs we see that they have an aperture f / 1.8 (aperture of the main lens) and not f / 2.0 (aperture of the telephoto lens).
This is still a curiosity. As we have seen, the end result for the user is the same. However, at the time of pressing the x2 button in the Camera app, the iPhone does a much more complex process than simply switching from one lens to another.