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iPhone's Face ID isn't perfect, but you can make it better

Face ID has its quirks. Before you get frustrated, try these tricks.

Ariel Nuñez/CNET

A new batch of iPhones has landed, and with it comes the expansion of Apple's Face ID and the ability to make your face your password. 

Face ID is incredibly advanced facial recognition biometrics. Just glance at the phone, and it unlocks. When it works, it is pretty smooth -- but it's got its quirks. Especially for new users. 

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When I started using the iPhone X earlier this year, I found it failing for me throughout the day. Access denied when I wake up. Denied when I put on glasses. Denied at my desk. Denied on the couch. Why is this gadget telling me that I don't look like me? 

And every time it fails, it slows you down, prompting for a passcode to unlock. Cue the fist-shaking anguish. 

All of this is incredibly frustrating when you're accustomed to the ease and speed of a fingerprint scan on Touch ID. My old iPhone's Touch ID didn't care how I held the phone. It also didn't judge my squinty morning face, thank you very much.

But after a few weeks, the frequency of failures decreased. Face ID is designed to improve the more you use it. But something else changed, too. It got more reliable because I learned to better maneuver the phone.

For anyone new to Face ID and upgrading to the iPhone XS, iPhone XS Max and iPhone XR, prepare for a bit of a learning curve.

Take for instance the awkward dance of using Apple Pay, which uses Face ID to authenticate purchases. I felt like such a dork trying to pay with my face, holding up the line fumbling with my phone, looking like I'm trying to take a selfie just to get my morning coffee. 

After practice and plenty of flubs, I've gotten the Apple Pay rhythm down: Double-tap the side button, prescan my face as I approach the register, make the order -- then tap the phone to the NFC sensor to pay. 

I reached out to Apple for more advice, and got answers to questions of why it fails and tricks to making it work better. Here's a brief breakdown of what I learned, along with my own experience, and tips to try if you're having trouble.

How does Face ID work?

The tech of the face scan is packed into an area on top of the phone, called the True Depth Camera system. It scans the shape of your face with infrared light, a beam of 30,000 dots that are invisible to the human eye. As the phone creates a depth map of your face, the data is turned into a mathematical representation. It's encrypted and lives locked in your device, never backed up to the iCloud or anywhere else.

The system is focused mostly on the details around your eyes, nose and mouth. If you obstruct anything in that zone, you're going to get a fail. 

Face ID also looks for your eyes to be open and glancing toward the phone. And it works best if the phone is held 10 to 20 inches away from your face.

That means if you try to unlock the phone in bed while, leaning against a pillow, or with eyes squinted, or if you hold the phone too close to your face, you're going to get a fail. 

Does lighting matter?

No, for the most part. Remember, this is using infrared light to scan your face. That means it works indoors, outdoors and even in a pitch-black room.

You may have trouble if the camera sensor is being hit with direct sunlight. Intense sun could throw off the IR reader from getting a proper scan of your face. But any other household light shouldn't be strong enough to make a difference.

Are polarized sunglasses a problem?

Apple's answer: It depends. There are some sunglasses that don't work with Face ID, but other models -- even ones with polarized lenses -- will work just fine.

If your sunglasses are not working, then they are designed in such a way that the IR light is completely blocked from scanning your eyes. Apple says several sunglass manufacturers are designing future models to make sure they work with Face ID's system. 

Do I have to enter my password after every fail?

No. Sometimes Face ID will fail because it didn't get a good look at your face. You can quickly try again by giving the phone a "dip" with your hand. Move the camera away by bending your wrist back, pointing the camera to the sky. Then bring it up to your face again. 

After five unsuccessful attempts to match a face, it will require a password. It also requires a password when the phone is reset or if the phone has not been unlocked in two days.

But sometimes, entering a password is a way to teach Face ID and help it improve. If you have a significant change to your appearance, such as shaving off a full beard, Face ID will ask for a passcode to confirm your identity -- and then it updates your face data on file.

How does Alternate Appearance in iOS 12 work?

If you're having continued trouble with Face ID, then you may benefit from adding an "alternate appearance." This may be helpful if, say your day look is drastically different from your night look. Maybe you wear a funky pair of glasses on occasion. Maybe you are a performer with heavy makeup. Or maybe you just have bad luck with the phone accepting your just-woke-up face. In the latest operating system, a user can register two distinct, different looks.

In the settings menu for setting up Face ID, there will be an option to set up a second face as your alternate appearance. And although Apple doesn't promote it, this alternate appearance can be a completely different person, if you so choose.

If you do add another person, I'm told this shouldn't change your personal Face ID experience. By that, I mean you shouldn't get more fails for adding a different person on the other appearance. The two faces are two separate data files on the phone -- it's not merging the two into one hybrid face.

Am I just holding it wrong?

Using Face ID requires you to think more about how you hold the phone. You may have to move your head and arm to unlock it, making sure it can see your face clearly while you keep eyes locked on the screen. Don't expect it to work while multitasking.

It takes some getting use to, but it does get smoother over time. Except when it comes to unlocking the phone while lying in bed. I just gave up on that one.

iPhone XS review: Wait for the XR.

Apple Face ID: Everything you need to know.