Everyone says the Lumia takes lovely pictures, but many of mine are blurry and crappy. I generally take them by pressing the shutter button (why yes I am over 30.) This week I happened to take some by tapping the screen instead. Among other things it animated a little square box over the picture centered where I tapped. Intrigued, I took several pictures in quick succession where I tapped in different places. They were indeed different in some way, but I can't really tell why. I think it had to do with exposure, because I was taking pictures of a sunset and there was a big difference between tapping where it was bright and where it was less bright.
Example: these are all from a plane, so the fact the islands are essentially in the same place show they were taken in quick succession:
I have noticed that the tap-the-screen pics are not blurry, ever, so I will do that from now on. But I would like to know why it matters where I tap and what affects I can achieve that way.