After reading the initial blog at neutralday.com, I was expecting the Nikon D90 to be much better than the Olympus E-620, and was ready to accept this given the excellent reports of the D90’s image quality and the fact it has a slightly larger sensor and so should have less noise at high ISO.
However, on viewing the comparison images, I must admit I struggled to see much difference between the two at ISO 1600 and below even though NR was turned OFF, and in fact, it could be argued that the Olympus images looked better.
Nevertheless, the results certainly surprised me as the E-620 high ISO performance even with NR OFF seems better than my E-510 and certainly very usable.
At ISO 3200, the E-620 clearly has more noise than the D90 but I think it is still usable at that ISO.
Given the excellent lens range and the CCD-shift IS that the Olympus has, the “low noise at high ISO” was one of the very few reasons for people to prefer the Nikon over the Olympus.
Now I am not so sure the difference is that important, but I do know what is important to me – Olympus’s edge to edge sharpness – unlike the Nikon lenses which tend to be sharp mainly in the middle – unfortunately I usually compose my portraits with the subject’s eyes at the intersections of the thirds – well away from the middle.