>I've always had a problem with my D90 overexposing. I would >say 95 percent of my images are taken with -3/6 being >"baked in" using the b4 fine tune optimal exposure >menu setting. This gives me a zero (balanced) meter reading >with -3/6 baked in. Maybe its just my camera, or some of >these d90s, but even with this -1/2 I still usually have to >dial in additional underexposure if there is any sunlit areas >in a mixed lighting scene. I would say the majority of images >i discard are due to blown out highlights that are >unrecoverable (CNX2 and RAW). I continually struggle with >overexposure even with this -1/2 stop baked in. Evenly lit >scenes with lessor dynamic range of illumination are ok, when >i get into medium to high contrast settings with >sunlight/shade I usually will need to dial in additional minus >exposure compensation. I have shot identical images with >another semi-high end camera (non Nikon) that i have and do >not have this problem with that camera.
I had the same experience when I first got my D90, coming from a D50 with no exposure problems. I did some quick searching on the forum and ended up "baking-in" -3/6 exposure for the matrix metering reading only, not the other two. Everything has been correct since then. I can't say that I was smart enough at the time to check exposure in the focus spots, and since then I have just been able to forget about it and make the normal compensations for snow etc. that we do anyway.
There are enough of us that have done this that there must be something to it for general use.