Metering & Exposure
We used a subject with extremely high contrast to check the metering and exposure consistency of the three cameras. Sunlight streaming through a studio window, with the black velvet curtain in shadow gave us far more extreme tones than most shooting situations, even in high-contrast. The cameras were set to the default metering, each manufacturer’s version of a center-weighted matrix. The results were remarkably similar.
 

Canon Rebel T1i ISO 200	Nikon D5000 ISO 200	Olympus E-P1 ISO 200

Canon Rebel T1i ISO 400	Nikon D5000 ISO 400	Olympus E-P1 ISO 400

Canon Rebel T1i ISO 800	Nikon D5000 ISO 800	Olympus E-P1 ISO 800

As you can see in these samples, the appearance of the three cameras is virtually identical by eye throughout the ISO range. The histograms look slightly different, with only the Nikon showing a slight shift of the shadows, rendering them a little higher and more open, and a general (but very subtle) flattening and spreading of the highest values. This favors a broader rendering of tones (supplying more separation in the shadows and highlights), and if it was a significant difference it would result in a noticeably better-looking file. It’s interesting, and tips us off to some of the Nikon in-camera processing decisions, but is hardly important in the end result.

Canon Rebel T1i ISO 1600	Nikon D5000 ISO 1600	Olympus E-P1 ISO 1600

Canon Rebel T1i ISO 3200	Nikon D5000 ISO 3200	Olympus E-P1 ISO 3200

The default metering and exposure performance of the Olympus P-E1, Nikon D5000, and Canon T1i are pretty much identical, and they are all very good. They are seeing the same information, and above all, they’re consistent throughout the ISO range.