Periscope aka folded lens: What it is, how it works and why it’ll boost iPhone photography

A dedicated telephoto lens (aka zoom lens) found on some iPhones boosts iPhone photography with optical zoom capabilities. Future iPhones are rumored to allow for even deeper zoom by adopting a periscope lens (or foldable lens as it’s sometimes referred to). At its core, this technology diverts light through a prism and into a telephoto lens set at a ninety-degree angle to a rear-facing lens and buried deep inside the chassis.

A scene from Apple's showing Selena Gomez posing for a selfie with her iPhone 6s camera with a bunch of reporters in the background photographing her
Image credit: Apple

Optical zoom vs. digital zoom: What’s the difference?

Most people are familiar with digital zoom, a software technique that crops and scales an image without adjusting the camera’s optics, which leads to image artifacts like blurriness and pixelation. With optical zoom, however, the camera’s optics are adjusted to produce an image of higher optical resolution than what’s possible with digital or hybrid zoom.

The iPhone 7 Plus was the first iPhone model to offer a dedicated 2x telephoto lens.

On the iPhone 13 Pro and iPhone 13 Pro Max models, Apple’s customers get 3x optical zoom in and 2x optical zoom out when shooting photos (totaling 6x optical zoom range). This makes it easy to zoom in up to three times while maintaining focus and optical resolution of the image without visible quality degradation. You can also use up to 15x digital zoom when snapping photos and up to 9x digital zoom when shooting video.

Apple's marketing image showing the left profile of a gold iPhone 13 Pro Max with the rear camera system and the lenses protruding from the housing
Image credit: Apple

The iPhone 13 and iPhone 13 mini lack a telephoto lens so they’re limited to 2x optical zoom out and 5x digital zoom (3x for video). Read: How to remotely control iPhone camera

Quality photographic zoom lenses which feature focal length factors beyond 10x are typically found on DSLR cameras, as well as on expensive professional television and film cameras. On smartphones where space is at a premium, however, achieving high optical zoom ratios requires some rather creative engineering.

How a smartphone periscope lens works

Enter periscope lens, a technology that allows for a major increase in optical zoom capabilities that otherwise couldn’t be achieved in a miniature lens array due to the limited space. In a future iPhone with a periscope lens, utilizing a system of prisms and mirrors would bend the light 90 degrees to direct it deep inside the handset’s enclosure for magnification purposes, without making the phone any thicker than it needs to be.

How folded lens designs improve smartphone imaging

By achieving a longer focal length along the phone’s long dimension instead of sticking out from the back, a sideways lens array can achieve a lossless optical zoom beyond 5x that would not otherwise be possible with a normal lens enclosure.

As a smartphone technology in its infancy, a periscope camera isn’t perfect. The main downsides include darker low-light shots and the need to hold the camera steady to avoid blurriness when zoomed-in. Read: How to use burst mode on your iPhone camera

Which phones have periscope cameras?

Some flagship Android handsets boast periscope cameras, also referred to as periscope zoom lenses. Samsung’s Galaxy Ultra phones feature a periscope-style camera construction that can swap between 4x optical zoom and 10x hybrid zoom. Huawei’s P30 Pro and Vivo’s X3o Pro, both launched in 2019, feature 5x optical zoom.

Oppo’s Find X2 Pro and Reno 10X Zoom Edition were among the first to adopt periscope camera technology. Read: Quick tips for taking great photos with your iPhone

Unveiled in 2017, Oppo’s periscope smartphone camera design uses a precise prism mechanism that can dynamically adjust its angle in precise increments of only 0.0025 degrees to endure images remain clear and stable at a full 5x optical zoom.

Oppo and Huawei have also introduced 10x optical zoom smartphone camera systems.

When will iPhone get a periscope lens?

No iPhone models currently feature a pericope telephoto camera, but Apple is suspected to outfit future handset models with this new imaging technology.

TF International Securities analyst Ming-Chi Kuo, who is considered to be the most reliable of Apple analysts, wrote in a July 2020 research note to expect a new iPhone model equipped with a periscope lens system for the main wide camera sometime in 2022. In April 2021, however, the revered analyst revised his prediction saying a periscope-lens iPhone wouldn’t arrive until 2023. In December 2021, Kuo reiterated that a telescope lens won’t be coming to the tentatively named “iPhone 14” models that are releasing in 2022.

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So don’t expect pericope lenses to hit iPhones before the 2023 iPhone models.

We know Apple has shown interest in this technology because the company holds multiple patents on foldable lens designs. An Apple patent titled “Folded telephoto camera lens system” and published back in 2016, for example, outlines a folded telephoto lens system that may include multiple lenses with refractive power and a light path folding element.

An iPhone with a periscope telephoto camera is a question of “when,” not “if”.