You know your phone has that auto brightness setting? Well, what's the betting you're not happy with it, and most of the time your phone is too bright indoors and too dark outdoors? The idea of Lux is to stop that silliness and give you a proper level of brightness for wherever you happen to be at the time.There's a free version in the app store, but some settings are locked out and can't be used unless you buy the full version. Don't panic though, the free version is good enough to see if you want to buy it, and the paid version is only \u00a31.65, so it's hardly bank-breaking stuff.Lux\nFormat\nAndroid\nPrice\nFree, or \u00a31.63 for full version\nWhere\nGoogle Play\nThe idea is simple, Lux takes over your phone or tablet's light sensor, and either makes its own guess at how bright the phone screen should be or allows you to pair an illumination level with a preferred brightness. It's a simple idea, but one we're amazed isn't actually built into Android.Once you've installed it, there's a tutorial that guides you through the set-up and day-to-day use of the app itself. You're also guided through the options you need. There's some clever stuff here, like the ability to have the app manage the fading in and out of the backlight. You also get to tell it when you want it to make its decision about what the screen brightness should be. The default is set to assess the illumination when you unlock the phone. We think this is a pretty good time to do it, but you can set it to check periodically too, or also on a more constant basis, when the illumination changes significantly. We'd expect this setting to use more battery though.On unlock is ideal, because mostly you won't be walking outdoors from inside while gawping at your phone. And if you are, then a quick lock and unlock will fix the brightness. Or you can access the widget or tray setting to make changes manually.Configuration-wise, there are so many settings in here that you could spend a million years getting the backlight set up just right. We're not going to pretend that this is for everyone, but honestly for those of us with phones that just can't get this sort of thing right, it's a real blessing.We're also pleased to note that the app is able to dim the screen well below what your phone would usually be able to manage. This means that for very dark rooms, where even the minimum setting is too much, you can dim the backlight down to almost nothing. In fact, be careful here, because you can dim it to a level where the screen is very hard to see. That said, locking and unlocking the phone, should set it back.It might sound like the geekiest app ever, but we love it. It may well help save power on your phone, but there's an even bigger chance you won't have to do that hand-shield thing that becomes essential with most auto-backlights.