How far can the S21 Ultra really zoom?
Samsung claims up to 100x zoom from the Galaxy S21 Ultra's cameras. So what do you actually get at each step along the way? I pointed it at a sky lift over a kilometer away and shot the whole range, 1x to 100x.
Prefer to see the zoom test in motion?
This one is a written photo comparison, so there is no video to embed here. I put gadgets and cameras through their paces on the channel, though. Subscribe to catch new tests the moment they go live.
Editor's note (July 2026): This test is from early 2021 with the Galaxy S21 Ultra. Newer phones push zoom and AI processing even further, and the physics lesson below still holds. For a current, more extreme version of this idea, see my Duel of the Lenses, where a Samsung S24 Ultra takes on a Canon R7 with a Tamron 400mm lens.
The short version
The S21 Ultra is genuinely great up to 10x, where its two telephoto lenses do the work optically. Past that it switches to a digital crop with AI cleanup: 30x still resolves a bit more detail, but 100x is more of a party trick than a usable photo. It will not replace a dedicated camera yet, but 10x from a phone this size is remarkable, and it is where most people will get their best shots.
Excellent to 10x, a marvel at 100x, not a DSLR replacement yet.How the S21 Ultra's zoom actually works
Samsung packed the S21 Ultra with five cameras, headlined by AI-enhanced zoom that claims up to 100 times. Unlike the S20, the S21 includes two telephoto lenses: one shoots optically from 1.1x to 3x, the other from 3.1x to 10x. Anything past 10x is purely digital, which means the phone is just cropping into the main image and leaning on AI to clean up the result. The AI helps with some of the blur, but it cannot defy the laws of physics around sensor size and optics.
Samsung pitched this as getting close to not needing a full DSLR for most shots. Will it? I let the results speak for themselves. The target for the whole test is the support gantry for a sky lift at the top of a mountain. According to Google Earth, we are roughly 3,600 feet, or about 1,100 meters, away from it, with a radio tower a further 400 feet (125 meters) beyond that.
The zoom test: 1x to 100x
Here is the full range, shot from the same spot. At 1x we start on the main 108-megapixel camera, where the gantry is barely a speck in the distance. Watch how it grows, and where the image starts to fall apart.
The turning point is clear. Up to 10x, the two telephoto lenses keep things sharp. At 30x we are into the hybrid setup, maxed out on the 10x optical and letting the AI enhance a digital crop. You can pick out a few smaller pieces of the gantry you could not before, but as a whole it is not as crisp as 10x. By 100x we hit the phone's ceiling, and while the idea of 100x is cool, the result is really just something to marvel at. There is no more real detail there than at 30x that you could not get by cropping into that shot afterward.
Can the S21 Ultra replace a DSLR?
The 100x shot is not clear, but it is still amazing that the tech exists in a phone this small. My honest read is that most people will get their best shots at 10x, and that future processing updates will keep improving those hybrid zoom levels. In my opinion this phone cannot replace a dedicated camera just yet. I also tried closing that gap with clip-on glass in my CoPedvic smartphone lens kit review, with mixed results. But given the direction Samsung and Apple are both heading, it will not be long before most people, even at the prosumer level, can get the shots they want from just their phone. If you want to see how much that gap has closed since, my Duel of the Lenses pits a newer Samsung against a real mirrorless camera and telephoto lens.
Frequently Asked Questions
How does the Samsung S21 Ultra zoom work?
The S21 Ultra has five cameras, including a 108-megapixel main camera and two telephoto lenses: one optical from 1.1x to 3x and another from 3.1x to 10x. Up to 10x the zoom is essentially optical. Anything beyond 10x is a digital crop of the image with AI cleanup, not true optical zoom.
What is the best zoom level on the S21 Ultra?
Up to 10x, which is the top of its near-optical range and where the image stays sharp. That is the sweet spot and where most people will get their best shots. It resolves clear detail even on a subject over a kilometer away.
Is the S21 Ultra 100x zoom any good?
Not really usable. Technically the phone does reach 100x, but the result is soft and holds no more real detail than the 30x shot. It is more of a marvel to look at than a photo you would actually keep.
Is 30x zoom on the S21 Ultra usable?
Somewhat. At 30x the phone is maxed out on its 10x optical zoom and uses AI to enhance a digital crop. You can make out a few smaller details you could not at 10x, but the overall image is noticeably softer and less sharp.
Can the Samsung S21 Ultra replace a DSLR?
Not yet. It gets impressively close for casual and even prosumer shots, especially at 10x, but a dedicated camera still wins on reach and image quality. Smartphones are closing the gap quickly, though, as my newer smartphone-versus-mirrorless comparison shows.
Disclosure: This post contains affiliate links. As an Amazon Associate I earn from qualifying purchases, at no extra cost to you. CK Tech Check is 100% ad-free: no banner ads, no ad tracking. Affiliate links like these and my YouTube channel are what keep the site running.