D300 Noise 400-6400 ISO at different exposures

[JamesA]

Just wanted to see how exposures from 0 to -4 stops effected noise, colour, contrast relative to each ISO.  For instance, 1600 at normal exposure looks better (less noise) than 400 at minus 2 stops.  However, at 1600 overall contrast appears lower and at 400 minus 2 stops there is compression of tones happening.

http://www.pbase.com/andersonrm/nikon_d300_noise_tests