[Remxed]

is it me or do the new LED screens for the 15" mbps kinda dim ever so slightly on and off after a while even when the screen is active?

[jtrwallace]

Is the light changing in the room in which your MBP is in? The ambient light sensor detects how much light is in the room and adjusts the screen brightness accordingly for optimal viewing. In lots of light, the screen is at its brightest so as to stand out and be easily visible. In low light, or in complete darkness it is at its dimmest because you need very little screen brightness to see the screen comfortably. If it was really bright in the dark, your eyes would hurt trust me. But for inbetween light ranges that sometimes change, the dimness will adjust accordingly.

[chris v]

You could be inadvertently putting part of a hand over the ambient light sensors. I do this occasionally with my Powerbook. They're under the grills on the sides of the keyboard.

[Remxed]

ah ok that's probably it.
thanks a lot!

[EndlessMac]

I've read that you can turn off the automatic screen dimmers. You might want to try that out if you don't like it constantly changing.

[kga1978]

System preferences/Displays -> Turn off "Automatically adjust brightness...."

[OreoCookie]

Also, LED screens don't dim down smoothly, but in discrete steps (think of light bulb vs. LED).
Hence, you'll be more likely to notice it as a `flicker' when your hand covers the ambient light sensors for a second or so.