What the hell does the telephoto lens on your phone do?

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The days when your phone had a single camera on it are gone. Nowadays, it’s common to have several of them on the rear of a device, or, if you’re Nokia, many, many more.

Thing is… why? What are they all there for? What do they do?

Well, we’re here to answer that question. We’ve already looked at a time-of-flight (ToF) camera, but today we’re pondering something else commonly found on the back of your phone: a telephoto lens.

So, pray tell, what is a telephoto lens?

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Now, modern phone photography relies on using several different types of lenses, then combining those shots with software into the final image you see on your screen. The part that a telephoto lens plays in this process is distance.

Basically, this means the telephoto lens helps take pictures of things that are further away, without the need of digital trickery to provide a zoom. The more optical zoom a lens has, the higher quality photos it can take from afar.

Currently, the Huawei P30’s telephoto lens has the highest amount of optical zoom on a phone (5x), which is substantially more than the 2x found on the iPhone XS and Galaxy S10.

The telephoto lens on phones is a vital part of that blurred background, bokeh effect you see in so-called ‘portrait mode’ shots these days. Of course, it doesn’t do this entirely by itself (a ToF camera is also an important part of producing these pictures), and software can do a lot of the legwork, but a telephoto lens helps.

So, there you have it, a short description of why you have a telephoto lens on the back of your camera. Something that can basically be summed up with the word zoom. Stay tuned for more breakdowns of phone photography.

Story by Callum Booth

Callum Booth is a freelance journalist with over a decade of experience. Previously, he was the Managing Editor of TNW, where his reporting (show all) Callum Booth is a freelance journalist with over a decade of experience. Previously, he was the Managing Editor of TNW, where his reporting was cited widely, including in VICE, the FT, and the BBC. Callum’s writing has appeared in The Verge, The Daily Telegraph, Time Out, and many more. He covers the full spectrum of technology, with a particular focus on how it shapes our daily lives. And a lot of regulation stuff too. Outside of work, Callum’s an avid bookworm, a Fisherman’s Friends addict, and resolutely unshaven. Follow him on Twitter @CallumBooth or visit www.callumbooth.net.