If you're passionate about taking photos with your mobile phone, you've surely seen that in more than one technical specification sheet. "periscopic zoom“or “periscopic camera” And you've been left wondering. It's not just a marketing buzzword: behind it lies a significant change in how smartphones manage to zoom in without having a huge camera stuck to the back.
In just a few years we have gone from having a discreet 2x zoom on mobile to have 5x, 10x and hybrid modes up to 100x In some high-end models, this is achieved while maintaining a relatively slim profile. All of this is made possible by a combination of advanced optics, prisms, mirrors, high-resolution sensors, and much more. processed with artificial intelligence.
What is periscope zoom on mobile phones and how does it differ?
When we talk about periscope zoom on a smartphone, we are referring to a kind of telephoto camera which positions the lenses and sensor perpendicular to the camera window, using one or more prisms or mirrors to deflect the light 90 degrees, mimicking the operation of a submarine periscope.
In a classic camera telephoto lens, the The lenses are aligned directly in front of the sensor.taking up considerable depth. If we were to transfer that design exactly to a modern mobile phone, the rear module would protrude significantly and the phone's body would be considerably thicker, something difficult to accept in current design.
The periscopic approach turns the problem on its head: The sensor and lens assembly are positioned along the chassis of the mobile phone.On one side, the window you see from the outside is just the light's entrance. Directly behind this window is a prism or mirror that turns the light's path 90 degrees so it travels through an internal tunnel before reaching the sensor.
Thanks to this trick, engineers can use focal lengths equivalent to 100 mm or even more (compared to the typical ~50mm of many classic mobile telephoto lenses) without creating a huge "hump". This longer focal length makes it possible to get much closer to the subject without relying solely on digital cropping.
In many designs, architecture takes the form of an L-shaped optical tunnelwhere the long section is positioned parallel to the plane of the phone. The longer this section, the greater the distance between the lens and the sensor, and therefore the greater the optical zoom that can be achieved.
How the periscopic mechanism works step by step
To fully understand what's inside the mobile phone, imagine the inside as an L-shaped tunnel that takes advantage of the width of the phoneAt the end facing the outside there is a small window (usually rectangular) through which light enters into the zoom module.
That light first hits a prism or system of mirrors that deflects it 90 degreesFrom there, instead of moving "inwards" into the phone, the light moves laterally inside, following that long arm of the periscope.
Along that route, several lenses are placed that are responsible for to focus, direct and “enlarge” the image before it reaches the sensorIn some designs, some of these elements can be moved slightly to adjust focus or vary the magnification, just like in a traditional camera zoom lens, but compressed into a mobile version.
The important thing is that this internal journey is longer than the thickness of the phone itselfThat's the key to achieving true telephoto reach without the module protruding excessively. The sensor is located at the end of the tunnel, where it receives the magnified image, ready for processing.
When you move the zoom control in the camera app, the phone can move certain lens groups within the module Or, in many cases, directly change the sensor (from the main camera to the periscope camera) and combine the optical result with digital cropping and AI algorithms to fine-tune the detail.
Why periscope zoom has been a turning point
The boom for this technology came in 2019 with the Huawei P30 Pro, one of the first mobile phones to popularize periscope zoom on a large scale. This model offered a 5x optical zoom, far superior to the usual 2x zoom of the time, and a 10x hybrid mode that was surprisingly high quality for the era.
In practice, this meant that, with regard to the main camera, the user could get five times closer to the subject without noticeable loss of detailStarting with the 5x optical zoom, the P30 Pro used a hybrid of cropping and advanced processing to reach that 10x while maintaining a very respectable result.
From then on, other manufacturers joined in force. Samsung entered the game with the Galaxy S20 Ultra, followed by the Galaxy S21 Ultra, S22 Ultra and S23 Ultra, all with periscopic telephoto lenses capable of high magnification and hybrid zoom modes that reach up to 100x.
Android models such as the following have also stood out: Xiaomi Mi 10 high-end, the Mi 10 Ultra with up to 120x hybrid zoomThe Realme X3 SuperZoom and the OPPO Reno 10x Zoom and Find X2 Pro, which used the periscope telephoto lens as a major selling point of their photographic capabilities.
Even Apple, normally more conservative in these changes, has adopted the system in the iPhone 15 Pro Max, with a 5x periscope telephoto lens and up to 25x digital zoomOther brands like Honor have also opted for it in models like the Magic 5 Pro, consolidating the periscope as something almost obligatory in the premium high-end range.
Advantages of periscope zoom lenses compared to other telephoto lenses
The biggest advantage of this architecture is that it allows achieve long focal lengths without swell the camera moduleBy placing the sensor and lenses to one side and guiding the light with prisms or mirrors, the limited internal space of the phone is used to its fullest potential.
Translated into everyday terms, this becomes a real approach to the subject with very little loss of sharpness...provided we remain within the optical zoom range. Unlike pure digital zoom, here the magnification is achieved physically with lenses, not by "inventing" pixels via software.
Another important advantage is versatility. In just one mobile phone you can have an ultra-wide-angle lens (0,5x), a main camera (1x), a short telephoto lens (2x or 3x), and a periscope long telephoto lens (5x or more)This allows you to go from a very wide shot to a distant detail without having to move from the spot.
Manufacturers also take advantage of the long optical range to take hybrid zoom even furtherStarting with a 5x or 10x periscope zoom, they add digital cropping and AI, reaching impressive figures like 50x, 100x, or 120x. The higher the zoom, the greater the reliance on software and the lower the quality, but it's still far superior to using only digital zoom from the main camera.
In portrait photography, many mobile phones use equivalent focal lengths of around 85-135 mm to achieve a comfortable compression of the facial features and an attractive background blur. Here, a 5x periscope lens is especially useful for achieving very close-up shots with a well-separated background, provided the light is good.
Image quality: optical, digital and hybrid zoom
To fully understand why there is so much talk about the periscope, it is important to make a clear distinction. optical zoom, digital zoom, and hybrid zoomconcepts that marketing mixes with joy.
El optical zoom It's the same old method: it's achieved by moving the lenses or changing the lens, so the image reaches the sensor already magnified. There's no cropping or pixel interpolation, so all things being equal, it's the same. It is the best quality option, preserving sharpness and fine detail.
El digital zoomInstead, it crops a central area of the image and expands that fragment using software, filling in information that doesn't existThe more you force this type of zoom, the more noise, artifacts, and loss of detail appear, especially if you then want to view the photo at a larger size.
El hybrid zoom It combines the best (and some of the worst) of both worlds. First, it stretches the optical range of the periscopic module From there, progressive cropping is added along with AI-based enhancement algorithms. This allows for greater reach while maintaining reasonable quality for a significant portion of the journey.
In today's high-end market, processing and artificial intelligence have advanced so much that a Moderate digital zoom (up to 2x-3x on the main camera, slightly more on the telephoto lens) It offers very useful results for social media and small screens. However, when you want to print or review the photo at 100% on a monitor, it's clear which part of the range is optical and which is purely software-based.
Periscopic zoom behavior in real-world situations
In everyday use, the periscope zoom shines especially in scenes where you need great distance from the subject: wildlife, sports, concerts, distant architecture or details of buildings when you travel and can't get any closer.
With a good 5x optical zoom you can achieve high-quality close-ups from the stands of a stadium or from the other side of a riverIn the most advanced mobile phones, some modules reach 10x optical zoom, which opens up even more possibilities for capturing distant scenes without extreme cropping.
From there, hybrid modes come into play. In many high-end models, the The range between 10x and 20x is still quite usableEspecially in good light. Above 30x magnification, the quality starts to drop noticeably, but it's still useful for seeing or documenting details that would otherwise be invisible.
Therefore, in the night performance The periscopic zoom makes all the difference the quality of the sensor, the optical image stabilization (OIS), and the processing softwareTwo mobile phones with similar zoom specifications can perform very differently when the sun goes down.
Zoom continuity: the great challenge today
There's an important trick in mobile photography: when you slide from 1x to 5x on the interface, you're actually There is no single lens that continuously changes its focal length like in a professional camera zoom.
What happens behind the scenes is that the mobile phone goes jumping between different fixed sensors (ultra-wide, main, short telephoto, periscope telephoto) and filling in the intermediate sections with digital cropping and AI. That's why, at some intermediate zoom levels, you see jumps in color, contrast, or detail that seem somewhat "magical" in the viewfinder.
These abrupt changes sometimes cause a photo taken at an intermediate zoom level to have lower quality than another one made right at 1x, 3x or 5xEven though you're theoretically "zooming in," the phone is simply choosing the most efficient sensor and calculating the costs for the others.
To tackle this problem, several brands are working on continuous optical zoom systems for mobile phonesThe idea is that a single module can smoothly vary its focal length, maintaining sharpness throughout the entire range, just like a professional video zoom lens but in an ultra-compact format.
Sony already experimented with something similar in the Xperia 1 IV with a limited range, LG showed concepts a few years ago, and more recently Tecno has presented a system called «Freeform Continuum Telephoto» which, on paper, would allow continuous optical zoom from 1x to 9x using so-called Alvarez lenses.
Continuous zoom and new periscopes: what's next
The Alvarez lenses employ two free-form surfaces that move perpendicularly to the optical axisBy sliding one over the other, the power of the set varies without physically lengthening the lens, which fits very well with the requirements of a slim mobile phone.
This type of design would allow a single module capable of covering a wide zoom rangeThis avoids jumps between different cameras and improves continuity of color, exposure, and detail. If implemented correctly, it would be a significant improvement over current fixed-step systems.
In addition, Tecno has showcased another teleperiscopic concept called «Dual-Mirror Reflect Telephoto»focused on reducing volume. Instead of a single prism that deflects light 90 degrees, this system makes the light bounce several times off several internal mirrors, further folding the path within the module.
According to the brand, this coaxial optic could reduce the module's volume by 50% and its external height by around 10%.This is a very attractive feature if we want slim phones with powerful telephoto lenses. The downside is that the central obstruction of the mirror system alters the shape of the background blur.
Instead of a classic round bokeh, the blur tends to adopt a "donut" or ring shapeThe manufacturer sells it as a curious artistic effect, but in reality it is an inevitable consequence of how the mirrors are arranged.
Other types of zoom and how the periscope fits in
When talking about periscopic zoom, it's inevitable to compare it with The other types of zoom found in mobile phones: classic optical, digital, and hybridwhich coexist in almost all modern models.
Digital zoom was the first to arrive on smartphones and simply virtually enlarges the image through cropping and interpolationThe more we force it, the further we move away from the real scene: invented details, poorly defined edges, and, in general, a lower quality image.
El traditional optical zoom It depends on the focal length and the ability to physically vary that distance with lenses. If we increase the focal length, we get a realistic zoom in without losing detail. The resulting photos retain their native resolution and a more natural texture.
El hybrid zoom arises from the mixture of bothIt starts with an optical base (either a conventional telephoto lens or a periscope lens) and relies on digital cropping and AI to go a little further without destroying the image as quickly as a pure digital lens from 1x magnification would.
In this context, the periscope is crucial because It greatly improves the optical starting point.If we start from a real 5x or 10x, the extra digital zoom that needs to be applied to reach 20x or 30x is much less, and therefore the final quality suffers less.
Mobile phones that feature periscope zoom and standard ranges
Today, most Mobile phones with periscope zoom belong to the high and premium range.This applies to both Android and iOS. Implementing this architecture remains expensive and complex compared to a classic 2x or 3x teleconverter.
On Apple's side, the clearest example is the iPhone 15 Pro Max, which features a 5x periscopic telephoto lens complemented by up to 25x digital zoom. The rest of the brand's models have shorter telephoto lenses without this type of system.
In Android, Samsung has spent several generations refining its periscope modules in the Galaxy S Ultra series: The Galaxy S20 Ultra paved the way, followed by the S21 Ultra and S23 Ultra., with huge hybrid ranges of up to 100x from a powerful optical telephoto lens.
Despite its commercial problems, Huawei remains a benchmark with its high-end P and Mate series...in which periscope zoom has played a key role since the P30 Pro. Xiaomi has launched aggressive offerings such as the My 10 Ultra with a striking 120x hybrid zoom, supported by a strong legal process.
Other brands such as realme and OPPO have made a strong commitment to the periscope. with models such as the realme X3 SuperZoom, the OPPO Reno 10x Zoom or the Find X2 Pro, which have used this technology as a differentiating element in their catalog.
Applications of periscope zoom in photography and video
In everyday photography, the periscope zoom shines when you want to capture distant details without physically movingIt is ideal for birds, animals in the wild, subjects on a stage, players in a game, or architectural elements that are out of your reach.
For portraits, a 2x or 3x magnification already works very well, but a 5x can offer very tight, expressive shots with a very compressed backgroundCombined with portrait mode and aperture simulation, you can get a look quite close to that of a dedicated telephoto camera, always remembering that the mobile phone's sensor is smaller.
In video, periscopes are starting to gain prominence. The combination of Optical image stabilization (OIS) and electronic image stabilization (EIS) It allows recording clips with a lot of zoom without the shaking being unbearable, although maintaining a homogeneous quality throughout the entire range is still more difficult than in still photography.
The world of professional video demands, in addition to quality, Smooth zoom transitions, without exposure jumps or abrupt focus changesBringing something like a "parfocal zoom" (which doesn't lose focus when zooming) into a tiny smartphone module is one of the great challenges of continuous zoom technologies.
Meanwhile, most manufacturers are increasingly refining their algorithms so that, when going from 1x to 5x or 10x zoom in video, changes in color, sharpness, and noise are minimized. be as inconspicuous as possible for the average user.
Looking ahead, everything suggests that periscope zoom will continue to be the best solution for having long-range telephoto lenses in slim mobile phonesWith the emergence of continuous designs, special lenses, and even more compact folding modules, each new generation further reduces the gap between smartphones and traditional cameras, making it easier and, above all, of better quality to get close to the action with your mobile phone than ever before.
