Why do we make double-triple-quadruple eyed cameras in smartphones instead of just improving the specs and keeping one lens?

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Why do we make double-triple-quadruple eyed cameras in smartphones instead of just improving the specs and keeping one lens?

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Multiple cameras allow using AI to assemble a better overall picture. For example if you overexpose one pic, and underexpose another a smart AI can puzzle a picture together that is perfectly lighted everywhere even though parts of the picture have vastly different lightlevels

The different lenses are for different purposes. You have a large ~~aperture~~ focal depth one for nice landscape pictures, you have a zoom one, you have a wide angle one for selfies and closeups or whatever. But given the very small amount of space available its extremely difficult to get good “does everything” results in a single lens and sensor stack. When you have a suitable all purpose or adjustable lens in a physical camera these can be several inches to several feet big, comprised of several dozen lenses inside that can move around; but even these are either very big and expensive, or are just good at one thing (telephoto zoom for example).

So its much easier (and thus cheaper) to put 3 sensors and 3 lenses in the camera, especially since real estate isn’t an issue anymore now that screens have to be like 10 or 11 inches.

edit: Aperture, focal length, whatever. I did mobile electronics but I wasn’t the optics guy.

When you make a lens, you have to give up something. That is, if you want a zoom lens, they generally are not as sharp, and don’t deal as well in low light as a prime (fixed) lens. They are also usually more bulky/longer/more heavy than prime. Fixed lens are sharper, and better in low light, but you give up flexibility with optical zoom. They also generally need less “glass” and have few or no moving parts. In many ways, good things for a very small space like a phone. Most phone makers have started using multiple camera lenses that (for the most part) are fixed, or nearly fixed prime lenses. You have an ultra wide, wide, and telephoto, for example. Often when you “zoom” on your phone, it is just changing between the lenses. Some have a little optical zoom. Some will also do a digital zoom for a bit before changing lenses, but in general the different lenses offer good low light, and different “zoom” levels.

It completely depends on the specific phone because there are many reasons a manufacturer my choose to do this.

One of the most common reasons is to have on camera that is either zoomed in farther or zoomed out farther to give the user the ability to change the amount of stuff in the picture without significantly lowering the quality.

On full sized cameras what is called optical zoom can be used, or an adjustable zoom through one lens, but this requires magnitudes more thickness than a smartphone can have.

Frequently they have different lenses for different purposes. Mine has one fixed focus for general use, one wide angle and one telephoto which it switches between depending on what settings/commands I use in the camera app. You can’t stack all of that functionality on one sensor/lens combo in the available depth, nor can you readily swap out lenses like on a dedicated, professional digital camera. So they just build in all three use cases because they’re pretty small and pretty cheap when they’re specialized like that.