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Here's the magic behind the Galaxy S20 Ultra's Space Zoom feature

Samsung Galaxy S20 Ultra Bader
Samsung Galaxy S20 Ultra Bader (Image credit: Daniel Bader / Android Central)

The Galaxy S20 Ultra brings something that most people would have never imagined possible with a phone camera: 100x zoom.

Samsung calls it Space Zoom, and while the full 100x shots we've seen aren't super crisp and perfectly clear, they are still pretty amazing when you think about it. You're getting 100 times zoomed-in shots from a tiny phone camera sensor and almost no actual focal length in the lens, and you can still tell what you're looking at. That's something that would never happen if you could pinch-zoom in 100 times, and it's pretty impressive.

How Samsung does it isn't 100% documented (some secrets are good to keep close to the breast), but it's also not entirely a new thing. We've seen companies like Huawei offer phone cameras with 50X zoom using the same methods, and even some small point and shoot stand-alone cameras do the same things. It's known as a periscope lens, and it's really cool if you're into knowing how things like this work.

Focal length

Lenses Sections Forms Refraction Light F Length

Source: Encyclopedia Britannica (Image credit: Source: Encyclopedia Britannica)

You've seen plenty of photos or even videos with absurd amounts of zoom, but they all have come from expensive cameras with really long and equally expensive lenses to get you closer to the subject without moving your feet. This is because of what's known as focal length.

Focal length is a measurement from the center of a camera lens and the point where all the light it collects comes into focus. It's not just a camera lens thing, either. Telescopes, microscopes, and even contact lenses all have a focal length. Sometimes it's adjustable like seen on a DSLR camera lens or a microscope, and sometimes it's a fixed point like most smartphone camera systems or contact lenses.

What's important about it for photographs is that shallow (shorter) focal lengths make for wider angle photos, but you have less of an ability to focus on objects at a longer distance. The opposite is true, too: the longer the focal length the more narrow the field of view is, but you can focus on objects further away.

You've seen focal length in action if you have ever used binoculars: far and narrow or close and wide.

If you've ever used binoculars, you've seen this in action. You can see things very far away, but you can only see a very narrow slice of the world around you. It's the trade-off that has to be made using optical lenses. Note that this is very different from digital zooming, where an image is electronically cropped and enlarged to fill the photo.

You can get away with a tiny bit of digital zoom in almost any smartphone camera, but if you want crisp and sharply focused photos of something more than 10 meters or so away, you need real optical zoom.

The periscope camera

Periscope Style Camera

Source: Oppo (Image credit: Source: Oppo)

Because you need a long focal length to get decent amounts of zoom from a camera system, it's tough to do it on a smartphone. Phones are thin, and even with an absurd camera bump, the sensor is still very close to the lens. As such, the focal length has to be quite short.

The solution is simple in theory: move the lens further away from the sensor. In reality, it's not so simple.

There isn't much room between the lens and the sensor on your phone, so some neat tech comes into play for telephoto.

What Samsung is doing is using what's called a periscope lens system. That doesn't mean anything pops up from the top of the phone like a submarine, but it uses the same idea — the lens and sensor are not mounted in a straight line, and prisms or mirrors are used to direct the light from the lens along the periscope tube back to the sensor.

As long as the mirrors or prisms are the correct shape and mounted at exact angles, this makes the focal length much longer without distorting the image. The render above is from Oppo and shows a 5x lossless zoom camera using this idea where light is "bent" through the lens and a system of prisms to hit the sensor on the right side.

Samsung is using a periscope lens arrangement and what it calls "Hybrid Optic Zoom" to have a full 10x optical zoom lens on the Galaxy S20 Ultra's telephoto camera.

10 times 10

Samsung Galaxy S20 Ultra Camera App

Source: Android Central (Image credit: Source: Android Central)

10X optical zoom doesn't sound like a lot and it definitely doesn't sound the same as 100X or even a little bit Space Zoomy. This is where two high-resolution camera sensors and some processing magic come into play.

10X optical zoom on a smartphone is pretty amazing, but it's far from Space Zoomy.

Once you pass the 10X zoom mark, the S20 Ultra's image processing uses digital zooming methods on image data collected from both the 48MP telephoto sensor and the huge 108MP main camera. The image is cropped and sharpened based on what the telephoto lens can "see," and light values and other sensory data the main camera sensor is collecting.

The image processing hardware and software algorithms on the S20 Ultra are very good. Using Qualcomm's DSP and software that's every bit as good as what Google can do with low-light photography, you can get a very nice photo at a very high amount of zoom. And you can also do what sounds impossible — get a photo that you can actually use at 100X zoom even if it's not the sharpest picture you've ever taken.

Jerry Hildenbrand
Jerry Hildenbrand

Jerry is an amateur woodworker and struggling shade tree mechanic. There's nothing he can't take apart, but many things he can't reassemble. You'll find him writing and speaking his loud opinion on Android Central and occasionally on Twitter.

6 Comments
  • The real question is how much zoom can be used in lowlight conditions like say a concert or late baseball game or indoor basketball game. If we can get even the optical zoom piece in those conditions then this is a real win.
  • Light is still key. Even my $2000 Nikon 200mm can struggle at full zoom with fast-moving, poorly lit subjects.
  • Good point, and Samsung can't make the sensor bigger to help because the sensor is now sideways in the phone body. Focal length or sensor size: Pick one!
  • It's not magic; it's 10x zoom with a crop.
    I've seen the shots, and would have deleted them due to image quality. That being said, I would have welcomed this camera on a recent photo-trip. My Nikon battery gave up in the middle of nowhere, and I didn't have my power inverter in the car to recharge. That left me with the 2x optical zoom on my phone, but it was not enough to capture details on a Pratt truss bridge that had been moved to fenced private property for preservation. "they all have come from expensive cameras with really long and equally expensive lenses"
    Not really. The Nikon B500 is a novice camera that you can get for $250, and it's zoom will embarrass Samsung's $1,400 device.
  • What does 10x zoom mean on a cell phone? i.e. What would be the 35mm equivalent?
  • Jerry, thank you for writing this. Is it wrong that I find it exciting to see attempts at new ideas being made? I get so much push back like "its not as good as a real camera, so it's dumb." I just refuse that, flat out. I used the S20 Ultra for like 12 hours one day and it is really fun to use. 30X in the right conditions turns out well. I caught an image of an older adult sitting on a bench with his head in his hand at 100x that isn't perfectly clear or even "clear," but its beautiful. I recognize this because I recognize the subjectivity in art and don't care to stifle expressions of the soul. This kind of attention to aesthetic metaphors is art, but it's also truth. Like, this camera, as a tool, with its flaws, allows for expressions that most mainstream phone cameras do not. "Get a camera." Sorry, Strawman argument. Someone in the forums bragging about being a "real photographer," and insulting people for how they make their bread is the antithesis of art, IMO. The soft hum of vinyl is an "imperfect thing," too. My grandmother has had works of photography in the Smithsonian before and two things I never heard from her were that she was a "real photographer," or that others were below her. She just saw a thing and wanted to share with others what she perceived to be a gift of beauty for all humanity that some may have just overlooked. Sorry for the rant buddy. I hope you feel better and again I really appreciate this write up because, hey, its more interesting than "smartphone comes out that is a smartphone."