eli5: What is the purpose and/or advantage of multiple cameras and lenses on a phone?

Question

As the title suggests, I don’t understand how this works.

In: 41

Answer 1

It allows for multiple focal lengths in a small package.

Zoom lenses are a very convenient feature for cameras, allowing users to frame their photos more easily – they allow you to take a photo of a big panoramic scene, zoom in on a detail up high and then turn around and take a selfie without moving all.

The problem with zoom lenses is that they need lots of moving parts which make them bulky and delicate – this is fine with a dedicated camera, but very inconvenient on something like a phone that needs to be both small and rugged enough to deal with being carried in a pocket or bag daily.

So if we can’t use a zoom lens, this leaves is with a couple of obvious options.

The simplest is to just to use one wide angle camera, and then digitally zoom in/crop the images. This is very easy to implement, but the more that you zoom in, the more the image quality will degrade.

So the current popular alternative is to use multiple camera units, each with a different lense of a different magnification.

Multiple cameras mean each unit can be made nice and thin (which is the critical dimension for most phone designs), and while they occupy more surface area on the rear of the phone, this is space that is much more freely available to the designers. It does add cost, but it also adds a big headline feature so that is a pretty fair compromise too.

With multiple camera units, you can switch between them to take a photo at the ~3 different focal lengths all at full quality, with the option to include an additional digital zoom to fill in the gaps between those three settings (and because they are only digitally coming a limited amount, this shouldn’t cause too much image degradation).