Compared to...

Studio scene comparison (higher sensitivities)

At ISO 800 the differences between the contestants are fairly small. At ISO 1600 the output of all cameras becomes softer. The Olympus shows signs of fairly strong noise reduction blurring. To a lesser degree these are visible on the Canons as well but the 450D holds up pretty well to its successor. The Nikon does the best job by maintaining more detail than the others and keeping the image relatively noise free, there are hardly any signs of chroma noise in its JPEG output.

Further up the sensitivity scale Nikon maintains its number one spot. The D5000's ISO3200 and 6400 results show visibly more detail than the 500D which also suffers to a greater degree from chroma noise blobs. The Olympus lags way behind at ISO 3200. The 500D is the only camera to offer an ISO 12800 setting. It might be useful to have to have this option in extreme situations, but the setting produces such ghastly color noise and generally horrible output that it should be firmly reserved for emergencies.

ISO 800

Canon EOS 500D	Nikon D5000
Olympus E-620	Canon EOS 450D

ISO 1600

Canon EOS 500D	Nikon D5000
Olympus E-620	Canon EOS 450D

ISO 3200

Canon EOS 500D	Nikon D5000
Olympus E-620

ISO 6400

Canon EOS 500D	Nikon D5000

ISO 12800

Canon EOS 500D