iPhone 4S sensor move forces case makers to scramble

In a small nightmare for both users and manufacturers, Apple has moved the ambient-light sensor on the iPhone 4S a few millimeters to the left, making some iPhone 4 cases incompatible with the iPhone 4S.

David Carnoy Executive Editor / Reviews
Executive Editor David Carnoy has been a leading member of CNET's Reviews team since 2000. He covers the gamut of gadgets and is a notable reviewer of mobile accessories and portable audio products, including headphones and speakers. He's also an e-reader and e-publishing expert as well as the author of the novels Knife Music, The Big Exit and Lucidity. All the titles are available as Kindle, iBooks, Kobo e-books and audiobooks.
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David Carnoy
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The ambient light sensor (ALS) has moved slightly to left in the new iPhone 4S. Lifeproof

You may not have been happy when Apple released the iPhone 4S instead of an iPhone 5, but a lot of case makers were. That's because at first glance their existing iPhone 4 cases seemed to work just fine with the new model, which meant that they didn't have to scramble to create new designs and had a ready supply of cases available for the 4S.

But that was before someone noticed that Apple had made a small but somewhat crucial design change: it moved the ambient-light sensor a few millimeters to the left. That created a problem for many rugged cases that covered more of the front of the iPhone: instead of peeking out through a hole cut into the case, the sensor was now hidden behind the case.

With no light penetrating, the sensor thinks the phone is in a darkened room and automatically dims the screen to look less blinding and save battery life. In the settings menu, you can manually set the screen brightness, but when in "auto-brightness" mode, the ambient-light sensor adjusts the brightness on the fly according to the ambient lighting conditions.

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Some iPhone 4 cases also didn't have a large enough cutout for the new camera in the iPhone 4S.

In responding to inquiry about which OtterBox cases worked with the iPhone 4S, a company rep told us that with the exception of the Reflex Series, none of the older cases designed for the iPhone 4 cases would "accommodate the new iPhone 4S."

Now companies like Otterbox are creating universal fit cases by simply making the cut-outs larger.

As Otterbox informed us:

  • The ambient light sensor on the front of the iPhone 4S is in a different location than on the iPhone 4. Defender and Impact Series cases designed for iPhone 4S have a larger opening around the sensor to accommodate all versions of the iPhone 4 and 4S.

  • The camera on the iPhone 4S contains new hardware, which produces a dark "halo" around images taken with a Commuter Series case for the original iPhone 4 on the device. The camera cutout on all OtterBox cases designed for the iPhone 4S is larger, allowing for proper camera functionality with all versions of the iPhone 4 and 4S.

While all of this should be sorted out soon, it has created a small headache for some case manufacturers. LifeProof CEO Gary Rayner, who's seen in the video below explaining the problem and who stopped by our offices earlier today, said that if you bought a LifeProof case on or after the day the iPhone 4S launched (October 4), you can send your case back and get the new version when it's released in the next couple of weeks.

That said, in an interesting twist to the whole saga, if you bought a white or pink LifeProof iPhone case, the light passes through the case just fine and doesn't impact the sensor. But ,Rayner says, you can return the old case regardless of what color it is.