MicrostockGroup

I often hear a phrase "my photo was rejected for noise/artifacts despite it was made at ISO 100". Some people don't realize that the issue is not with the ISO but with sufficient exposure. Underexposure will result noise and artifacts in shadows even at low ISO.х.

To give you an opposite example:

this picture was taken with ISO 800 (Canon EOS 40D), no flash, fluorescent light and manual focus. It was accepted by iStock (and others) even without downsizing.

No special tricks used during post-processing. Normal RAW conversion, then standard retouching, brightness/contrast using curves etc. The only filter I used is a slight touch of deJPEG that I apply to virtually all photos.

Correct.
My point isn't about shadows, it's about underexposed pictures. Underexposed pictures will get noise and artifacts even at lowest ISO even with a best camera.

Good example and point, but it's not only about exposure, but also lighting. As previous poster mentioned you can't make it pass with shadows in the shot, so the photo has to be evenly lit, like yours. So we need 2 components. Having a FF camera with good Hi-ISO performance helps enormously as well

Are you a aware that this is a 2009 thread ?