I've meant to do a metering test on my camera since I got it 1-1/2 years ago, but it's a boring test, so I kept putting it off. Finally, I located my gray card, grabbed a chunk of black mat board, and set the two cards up against a white mat board with a red board a base. I set the metering mode to spot, then took a picture metering for black, a second picture metering for middle gray, and a third picture metering for white. Because these photos were done in RAW mode, I increased white levels in all three pictures the exact same amount because my camera tends to be a bit dark when set to RAW.
I thoughtsome of you might be interested in seeing the different results you can get depending on what you meter for: