I've always been under the impression that the "brightness" button on
my Apple 20" was a backlight control, but if that is the case why does
my "native" whitepoint (as measured by Optix XR Pro) fluctuate from
6500k at full brightness to 7000k at minimum brightness?
All the desktop LCD monitors with which I am familiar use fluorescent
lamps for the backlight. As the voltage changes during the dimming
process, the color temperature of the fluorescent lamp changes. This is
a well known property of the technology. In fact, as the fluorescent
tube ages it's color temperature changes, too.
