Automatic display brightness not working on 2012 Air?

Question

I have a 2008 aluminum MacBook which I bought on day zero. The automatic screen brightness on it works perfectly. When I am in a dark room, the brightness goes down significantly, so I am not blinded. When I am in a bright room, the brightness goes up. The keyboard backlighting is equally consistent and works great. It's all worked perfectly for the past four years.
I now have a 2012 Air and the automatic brightness doesn't seem to work as well. It barely seems to change the brightness. I use it in a pitch black room and the brightness goes down a bit, but no where near as low as on my MacBook. I have to manually turn it down further. Another example: I had it turned down last night, but right now, typing in a sunny room, the brightness has barely raised (when I push the brightness button, it shows it at four bars).
I never notice the keyboard backlight change. It also never seems to turn off, even when I am in direct sunlight. On my MacBook, it turns off in bright light.
I know the sensor is working, at least partly, because if I am in a bright room, I can cover the sensor with my finger and the screen dims a little.
Is this the expected behaviour? Does the keyboard backlighting never turn off automatically? Is your screen dimming enough in the dark? I literally never, ever, had the need to manually adjust my screen or keyboard brightness on my MacBook. On this new Air, the automatic brightness may as well be disabled, since it barely seems to do anything.

Answer 1

I think I have discovered the problem. The system remembers where you have manually set the brightness, and tries to stay around that level even when moving from bright to dark rooms.
I manually set the brightness to 5/8, waited a minute, then went outside in the sun. As expected, it adjusted to max. However, when I came back inside and sat down, it only went down to 5/8 again. I guess earlier when it was going down to 3/8, it was just trying to get back to my manual setting (I had set it to 3/8 this morning while in my dark bedroom). Even if I completely cover the sensor, the brightness now only goes down to about 4/8.
On the MacBook, it used the full range of brightness and completely ignored any previous manual settings. I could use the automatic feature to completely control the brightness at all times. Now, with the Air, the automatic feature instead tries to maintain the user-selected brightness level as much as possible.
I'm not sure which style I prefer. I did like not having to ever touch the brightness buttons, although I admit it was occasionally too dim in certain situations. I would prefer that the Air dim much more when in completely dark rooms, and maybe the sensitivity of the sensor should be increased a bit.
Now the only issue is how the keyboard backlight seems to stay on in all conditions except in the sun! It is on now even though it is obviously bright enough in the room to read a paperback book, let alone a keyboard.