My Nikon D40 doesn't have the auto-bracketing feature so I have to set the exposure compensation on my own. I was just curious... for cameras that do have this feature, does the camera automatically set how much to overexpose and underexpose? because when I set the values on my own, I'm having trouble manually setting how much to overexpose and underexpose.. Also, does it have to have to be even values? (if I set +2 then I have to set -2)? If it doesn't... is it uncommon to have uneven values for + and -?