Measurements

The Dell 2408 specification says:
Luminance Output – 400 cd/m2
Contrast ratio – 1300:1

Factory settings for brightness and contrast are 50/50%
A usable range of brightness and contrast controls IMO would be:
Brightness 60% - 0%
Contrast – somewhat close around standard 50%

Below is brightness/contrast measurements summary.
Brightness control: 100% - 0%
Contrast control: 50%
Uncalibrated.