Hands-on With the Samsung Galaxy S7's Speedy New Camera
In low light, Samsung's new camera really pays dividends.
Much has already been made of Samsung's new flagships, the Galaxy S7 and S7 Edge. With beautiful displays, a water-resistant design, and a slew of new features, Samsung's new phones are better than ever.
But what about the camera? With a faster processor and new camera hardware that features fancy "dual-pixel autofocus," the Samsung Galaxy S7 and S7 Edge look like substantial improvements over last year's models, which were already some of the best smartphone cameras you could buy.
But what exactly is dual-pixel autofocus and how does it affect performance? More importantly, do these improvements actually show up when you use the cameras in the real world? We went hands-on to find out.
What Is Dual Pixel Autofocus?
Nearly every camera—from smartphones to DSLRs—have some method of automatically focusing on a subject so the user doesn't have to. There are two ways of doing this: contrast-detect focus and phase-detect autofocus.
Most smartphones use contrast-detect autofocus, which relies on a key principal: blurry, out-of-focus photos don't have much contrast. Imagine you're photographing a white picket fence against a black sky, like in the graphic below. If the fence is in focus, it'll look like the image on the left. If it's out of focus, it'll look blurry, like the one on the right. All the camera has to do is move the focus around until contrast is at its peak and voila, your photo is usually in focus.
Phase-detect autofocus is a little more complicated, but it works by calculating how far away a subject is and then focusing on that point. While it's sometimes a little less accurate, it's quicker. And since it isn't relying on contrast, it doesn't need as much light. This is how DSLRs autofocus so quickly, even in low light.
Some DSLRs and smartphones, like the iPhone 6s, have "focus pixels" which are just a select number of phase-detect pixels spread across the image sensor. The Samsung Galaxy S7 takes it a step further, with every pixel on the sensor acting as a phase-detect sensor. It's similar to the "Dual Pixel CMOS AF" that Canon baked into the Canon EOS 70D a few years back, though even with the 70D only about 80% of the sensor used them.
Putting it to the Test
To test Samsung's fancy new autofocus system out, we ran a few quick tests comparing the Samsung Galaxy S7 and S7 Edge with the iPhone 6S and last year's Samsung Galaxy S6 Edge. All three have phase-detect autofocus pixels on the sensor, but only the new S7 and S7 Edge have the new dual-pixel system.
We started in bright sunlight, focusing on a close-up subject before telling the camera to focus on our staff writer Michael Desjardin's face. All three cameras did exceptionally well; the iPhone 6S picked up Michael's face right away while the two Samsung phones did the same the moment we tapped the screen. So far, so good.
We then moved to our pitch black imaging test lab, lighting Michael's face from one side with about 25 lux of light—similar to what you'd get in a dim bar. The S6 Edge and the iPhone 6S both go through the same routine, moving the point of focus past Michael's face before backtracking and locking in. The S6 Edge does this in about 0.77 seconds while the iPhone takes a full second longer.
The S7 Edge is close to the S6 Edge at 0.833 seconds, but instead of hunting around it calculates where it needs to go and then moves to that point—no hunting required. You can see for yourself in the video at the top. It's impressive to witness, as the S7 even has time to make a slight exposure adjustment before focusing while still keeping up with its predecessor.
In the end, the results we recorded are right in line with our expectations: the Samsung Galaxy S7 doesn't drastically outperform existing flagship smartphones when it comes to bright light autofocus, but its dual-pixel autofocus is more effective and reliable in low light since it doesn't have to hunt around as much.
Does that make it a better camera than the iPhone or the 2015 Galaxy phones that it's replacing? Not necessarily, but it's a step in the right direction. Either way, it's clear that Samsung's attempts to improve this year's crop of cameras is already paying dividends.
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