What is a periscope lens: getting big zoom into a small phone

Vector graphic of a phone with a periscope
(Image credit: Future, www.vecteezy.com)

What is a periscope camera? Short answer: not a submariner snapping photos through the vessel's pop-up spy tube. Actual answer: an ingenious solution to getting a (relatively) long focal length into a device like a camera phone which would otherwise be too small to house an ordinary long lens.

Conventional wisdom dictates that to get serious zoom, you need a serious lens. Paparazzi shooters don't lug their hulking great bazooka lenses around just so they can look the part and scare A-listers. In order to magnify a distant subject, there also has to be a lot of distance between the front element of the lens and the camera's image sensor. Some optical trickery can be used to reduce the physical length of the lens while maintaining the same focal length, but that'll only get you so far. Big zoom = big lens, period.

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Ben Andrews

Ben is the Imaging Labs manager, responsible for all the testing on Digital Camera World and across the entire photography portfolio at Future. Whether he's in the lab testing the sharpness of new lenses, the resolution of the latest image sensors, the zoom range of monster bridge cameras or even the latest camera phones, Ben is our go-to guy for technical insight. He's also the team's man-at-arms when it comes to camera bags, filters, memory cards, and all manner of camera accessories – his lab is a bit like the Batcave of photography! With years of experience trialling and testing kit, he's a human encyclopedia of benchmarks when it comes to recommending the best buys.