M7: Motion coprocessor for iPhone 5S

Argus asks for Apple M7 access permission Strava Run asks for Apple M7 access permission
Accessing M7's motion data requires user permission

Probably the biggest new feature in the iPhone 5S that is completely hidden to an outside observer is Apple M7 (NXP LPC18A1), the motion coprocessor that handles a variety of sensor inputs (accelerometer, gyroscope, and compass) independent of the main processor, A7. Its main potential use is for health and fitness apps, and rightly so, they are the first apps to take advantage of it. Argus (Sept. 20) and Strava Run (Sept. 24) were updated right after iPhone 5S release to use M7. I see it as a big feature because this would enable a lot of apps to poll sensor data without draining battery much at all.

Interesting enough, when you run an app with M7 support, you'll be asked to allow access to motion activity. This is a good sense on Apple's part because these data can be easily used to track user's habits. GPS data merely tells you that a person was there. Motion activity data tells you how you were moving around there very precisely. Let's take a more careful look.
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Biometric scans of iPhone 5S

Unlocking the lock screen of iPhone 5S with the finger
Click, then keep the finger on the home button for an instant unlock

Apple acquired AuthenTec back in 2012, and a lot of rumours circulated about the possibility of iPhones using fingerprint sensors created by this company. Come 2013, this has come true in the form of an integrated fingerprint sensor called Touch ID on the home button of iPhone 5S. In the process, the iconic rounded square marking in the button was sacrificed in the name of progress. The physical button is still clickable as always. The sensor works only when you leave your finger on the button without clicking.

Many experts view biometric authentication such as fingerprint scanning as a good way to "augment" security. It is by no means a complete replacement for existing measures because you can't change your biometric characteristics, and the detection can be fooled with sufficient resources and will. So it's generally recommended that this is used in conjuction with another authentication method such as ID & password. That said, Apple has decided that it's good enough to be used as an alternate method of entering passcode for unlocking lock screens.

This doesn't sound good from strict security standpoint because the biometrics are used to "replace" rather than "augment". However, Apple's rationale is that a large number of people don't even set passcodes, and by providing this alternative in a convenient package, phones would be somewhat secure, than not secure at all. Then, the convenience angle must be sufficiently strong to gain traction.

Using this feature for some time, I can say that this would indeed be the case. Read on to see my demonstration.
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iPhone 5S camera's quality

iPhone 5 bright indoor shot iPhone 5S bright indoor shot
Full resolution crops of bright indoor shots - click for original
iPhone 5: 33mm - ISO 64 - 1/20s  ||  iPhone 5S: 30mm - ISO 64 - 1/30s

Apple has constantly improved the iPhone camera's overall quality over the years, and this time is no different. It has touted iPhone 5S's larger sensor (1/3.0", compared to 1/3.2" in iPhone 5) that results in bigger pixels (1.5 microns instead of 1.4) and brighter lens (f/2.2 instead of f/2.4) that lets more light in. These are supposed to gather 33% more light, and low-light performance would be improved as such. One thing not mentioned is the focal length. Both devices are fixed to 4mm, but 35mm equivalent values are different - iPhone 5 is 33mm, while iPhone 5S is 30mm. This means the latter has a slightly wider field of view.

iPhone 5's camera already takes great outdoor shots, so I felt that improvements from these upgrades would be most noticeable in indoor shots. Therefore, I decided to use both iPhone 5 and 5S to take several comparison photos in the house, with iOS version both at 7.0.2. First one shown here is taken in a brightly lit room, and the low ISO value tells you that the sensors should be subject to minimal noise. This should be typical of the photos that were taken with good lighting. You can see that both phones perform similarly, but iPhone 5S does apply slightly more smoothing. This makes the 5S photos in good lighting conditions look a little too clean. Fortunately, the details are mostly there and the file size did get a bit smaller on average as a result. This seems to be more or less the difference in post-processing pattern than the sensor performance itself.

iPhone 5 dark indoor shot iPhone 5S dark indoor shot
Full resolution crops of dark indoor shots - click for original
iPhone 5: 33mm - ISO 2500 - 1/15s  ||  iPhone 5S: 30mm - ISO 2500 - 1/15s

When the lighting is dramatically reduced, the difference in sensor performance becomes evident. The photos here were shot with identical ISO and shutter values, yet iPhone 5S's photo preserves the details of the objects and letters much more than iPhone 5's. You can make out the letters with 5S, while 5 gives you muddled goo. Both had noise reduction kicked in, but it iPhone 5 clearly had less detail to work with in the first place. Apple's efforts are paying off here.

Of course, camera module itself is only half the story. Let's take a look at a photo in even worse lighting and go from there.
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iPhone 5S camera's speed

Screen capture of iPhone 5S slo-mo video mode
Recording video at 120fps

One of the key improvements of iPhone 5S over previous generations would be the camera's performance. In this segment I'll look at the speed at which it can operate - namely, how fast the video and still photos are recorded.

1. Video

iPhone 5S introduces the "slo-mo" mode with 120fps capture at 720p (1280x720). What it actually does is that the phone records the video at 120fps fully. Then, when you view the video in the camera roll via the Camera or Photos app, a portion of the video is played in slow motion by reducing the playback speed to 30fps.

Screen capture of iPhone 5S slo-mo video editing
Picking out where you want it slow

This results in playback at 1/4 the speed for the selected "zone". You can adjust where the slow motion starts and ends by moving the sliders just below the frame strip. One drawback is that you can't set two or more zones. You'll need a separate editor or app to achieve this.

Also, there are some interesting consequences when exporting the video clips.
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Making iPhone 5S work on a Korean network

AT&T and SKT NanoSIM with iPhone 5S & 5 SIM trays
Free AT&T SIM found inside iPhone 5S


UPDATE (Sept. 25, 2014): There has been some changes in activating LTE devices from overseas in Korea. [Read the related iPhone 6 Plus review.]

When my friend Andy lined up to get the new iPhone 5S, the Apple Store had specific supplies of the phone for each of the four major U.S. carriers. If three of the carriers supposedly use the same model as seen in Apple's website, it might seem strange that this division existed. It turns out that each of the phones have a SIM card for the designated carrier, as well as some specific device status configured (SIM lock, CDMA enable). As you can see, Andy got me an AT&T version of the iPhone 5S with model number A1533, with the AT&T NanoSIM as a proof.

SK Telecom branch in operation
Yes, prepare to visit a carrier's branch
Now, Apple mentions that the model number of the iPhone 5S planned to be released in Korea is A1530, which forgoes the AWS and 700MHz bands used in North America and instead supports TD-LTE bands used in places like China. Interestingly, both models (as a matter of fact, all models) support LTE bands currently active in Korea, so it seemed likely that A1533 iPhone 5S would be able to hop onto LTE networks in Korea. This was the reason I risked buying A1533 outright instead of trying to get A1530 from Hong Kong or wait for official Korean release. It turns out my hunch was correct, but it's not completely plug-and-play. Read on to minimize the chances of bumping into problems.
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