Samsung’s Galaxy S24 phones and other recent smartphones have a new way to squeeze better camera technology out of all those pixels on high-resolution image sensors. That’s the part of your phone’s camera that actually records that sunset or your kid racing down the soccer field.

A few years ago, your smartphone probably had a 12-megapixel image sensor that took 12-megapixel images. But that direct relationship is getting looser, which is why an Apple iPhone 15 Pro shows a 2x camera option without actually having a dedicated 2x camera.

I call the technology “crop zoom,” and I’m a big fan of the approach. It’s not a gimmick.

It’s slowly bringing us some of the photographic versatility you get from a traditional camera with a zoom lens. To improve photographic flexibility, phones are sprouting additional cameras — the Samsung Galaxy S24 Ultra has four cameras on the back and a selfie cam on the front — but crop zoom gives you more photo options without more camera hardware. That means it can help you out, whether you own a flagship phone or a more modest model.

Samsung is using the technology in its newest Galaxy phones announced Wednesday. All the S24 models have a 50-megapixel main camera that’ll shoot lower-resolution shots at 2x zoom. And the Galaxy S24 Ultra has a new 50-megapixel 5x telephoto camera that’ll shoot 12-megapixel shots at 10x zoom, too.

Cameras have become the single most important feature on smartphones. Photos can be precious, and we can share them immediately with friends and family to bring them into the moment. Smartphone makers spend more time describing cameras than any other new feature, camera lenses have become showy bulges on the backs of our phones, and high-end phones have more and more cameras to cover more shooting situations.

You may have been warned about the empty promises of digital zoom, a pixel magnification technology that’s far less useful than the optical zoom that requires either a new camera module on a smartphone or a zoom lens on a traditional camera. Crop zoom is somewhere in between digital and optical zoom: a feature, not fakery.

Here’s a look at how the technology works, why it’s a good idea, and the situations where you need to be careful with crop zoom.

How does crop zoom photography work?

You’re probably familiar with cropping a photo, which simply means paring away the outer parts of a frame to concentrate attention on the important part of a scene. Crop zoom is the same thing, but it happens on the image sensor when you’re framing and taking a photo, not afterward while you’re editing.

What makes crop zoom useful now are all the new high-resolution image sensors cropping up in flagship phones. You often have so many pixels to start with that you can still get a usefully detailed shot even if you use crop zoom and eliminate a lot of those pixels.

For example, with Apple’s iPhone 14 Pro and 15 Pro models, the main camera can take 48-megapixel photos at 1x zoom. But you can also select 2x zoom, which takes a 12-megapixel shot with pixels just in the center of the sensor. That’s way cheaper than building a separate 2x camera hardware.

Google’s Pixel 8 Pro takes this a step further. Like the iPhone 15 Pro, it has a 5x telephoto camera. You can use it to take 50-megapixel photos. But Google also lets you use crop zoom to shoot a 12-megapixel 10x photo — essentially, getting twice as close but with just a quarter of the resolution. That’s the same approach in the Samsung Galaxy S24 Ultra.

A comparison of an iPhone 14 Pro main camera shooting at 1x and 2x mode. At 2x, a photo of a sleeping dog is framed more tightly. A comparison of an iPhone 14 Pro main camera shooting at 1x and 2x mode. At 2x, a photo of a sleeping dog is framed more tightly.

Crop zoom offers a different take on the same scene. At left is a shot taken with an iPhone 14 Pro 1x camera at 48 megapixels; at right, the same camera shooting at 2x and 12 megapixels.

Stephen Shankland/CNET

How useful is crop zoom?

In my experience as a photographer, very useful. Crop zoom isn’t perfect, but I see the glass as half full. It adds flexibility without requiring another entire camera module.

A 2x view often can make for a nicer portrait shot or help you frame a photo better when you can’t walk closer to the subject with a 1x camera. Midrange phones like the non-pro Pixel 8 and iPhone 15 get some telephoto reach. I appreciate the Pixel 8 Pro’s 10x option for identifying birds and for photographing mountains or other distant subjects. The telephoto reach offers a perspective you often just can’t get any other way.

Crop zoom isn’t as good as a dedicated smartphone camera. But that adds a lot of expense and makes phones bulkier. And because physics means telephoto cameras are physically large, it’s particularly hard to them into a thin smartphone, so crop zoom on telephotos has particular appeal.

And it’s nowhere near the continuous zoom range that traditional mirrorless or SLR cameras get with zoom lenses. Few of us carry those with us these days, though.

What’s the difference between optical zoom, digital zoom and crop zoom?

Optical zoom is when you have either a dedicated zoom lens or a dedicated camera module that lets you zoom in and out but still shoot at an image sensor’s full resolution. It offers the best quality, especially for serious photographers trying to snap shots of distant subjects like birds or athletes.

Digital zoom is an image processing trick used to magnify an image beyond its original pixels. Despite what you may have seen in the “enhance” scene from the Bladerunner sci-fi movie, phones can’t make up data that wasn’t captured in the first place — at least, not very well, though AI photo processing techniques can outpace old-school methods. If you’re shooting at 15x on an iPhone’s 3x camera, don’t expect too much.

Crop zoom is somewhere in between. It’s not fabricating pixels the way digital zoom does and certainly isn’t a mere gimmick, but it’s not as nice as proper optical zoom would be.

Samsung shows a series of increasingly magnified photos to tout 1x, 2x, 3x, 5x, and 10x zoom levels of its Galaxy S23 Ultra phones. Samsung shows a series of increasingly magnified photos to tout 1x, 2x, 3x, 5x, and 10x zoom levels of its Galaxy S23 Ultra phones.

Samsung touted the Galaxy S24 Ultra’s ability to take photos at 1x, 2x, 3x, 5x, and 10x zoom levels. It shoots at 2x and 10x thanks to crop zoom. (It’s also got an ultrawide camera.)

Samsung; Screenshot by Stephen Shankland/CNET

What are the shortcomings of crop zoom?

Cropping to use a smaller portion of an image sensor significantly reduces image quality. A bigger image sensor captures more detail, better color and a broader dynamic range between light and dark than a smaller image sensor taking the same shot.

If there’s plenty of light, crop zoom is fine, and the technology works well enough for me to use it a lot. When it’s dim, lower your expectations accordingly. Your smartphone camera will run into its limits a bit sooner.

That said, crop zoom to get you from 1x to 2x zoom takes place on a phone’s main camera, typically the one that has the largest and best image sensor with the fastest lens. So you’ll likely have more leeway for crop zoom there than with telephoto cameras.

Crop zoom isn’t like optical zoom on a traditional camera, where the full width of the sensor is used regardless of your zoom settings. That’s an area where traditional cameras still have a big image quality advantage over smartphones.

Where’s crop zoom technology headed?

We’ve had crop zoom for a couple years now, but expect it to spread and improve.

Lower-end phones will get it as high-resolution sensors become more affordable. Telephoto cameras could benefit from sensor and lens improvements too.

One notable trend is a greater disconnect between the native resolution of a sensor and the resolution of the photos that come from it.

Apple’s iPhone 15 Pro phones get not just 1x and 2x options from its 48-megapixel main camera, for example, but also 1.2x and 1.5x settings enabled by crop zoom. That’s the equivalent of 28mm and 35mm lenses in old-school SLR terms, compared with the 1x camera at 24mm. But all of them are 24-megapixel photos, which means Apple is massaging the final image with some image processing to convert the number of original pixels.

With even higher-resolution sensors, smartphone makers could get even more latitude. Don’t expect the continuous, fluid adjustment of traditional cameras. But crop zoom is a big step toward that flexibility.

And I’d like to see more of it. Hey, Apple, how about a 10x camera option on the iPhone 16 Pro later this year?

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