For a while now we've been seeing ourselves, and hearing from a lot of you about the magnometer (digital compass) in the iPhone 5s and how it's consistently presenting abnormal results, even by digital compass standards. Now I lack science powers enough to understand exactly how it's supposed to work, but ever since it launched in Android devices and the iPhone 3GS, I've never had great results with it. Frustrating, figure-8-circling, direction spinning results, yes. Great, no. But with the iPhone 5s, not great seems to have been taken to all new levels. Pun somewhat intended...
We've now done a bunch of comparisons since the the iPhone 5s launched, on iOS 7, 7.0.1, and 7.0.2, next to both the iPhone 5 and iPhone 5c, and it does indeed look like the iPhone 5s is off-level by a few degrees. As to compass direction, we're hard pressed to ever get multiple devices to agree which way, exactly, north lies. Our iPhone 5s forums are filled with members reporting exactly the same problem.
The compass inaccuracies aren't new to the iPhone 5-series, of course. Like I mentioned above, the technology itself, separated out from the rest of the motion sensors on the device, seems far, far better suited for gross measures than anything that needs pin-point accuracy. So, turn-by-turn navigation while a car is moving and everything else in CoreLocation can support it, perfectly fine. Trying to figure out how to take three steps due east, almost impossible. The level, however, just seems incorrectly set and en masse.
If it's a problem with software calibration, a future update, like the forthcoming iOS 7.1 should be able to fix it. While it will never be perfect, it should at the very least be as good as other models. So here's the take away:
Digital compasses aren't accurate enough to serve as scientific measures, period. They're convenient as far as converged devices go, and useful when combined with other sensors, but by themselves, never expect them to get you through basic training. Never.
The iPhone 5s deviates beyond the usual inaccuracies and inconsistencies found in digital compasses, perhaps indicating it needs better calibration, or some other fix from Apple.
That said, poll time. Vote up top and give me the details in the comments below.