Can anyone help?

I have a 20D + 580EX. Tried for fun to shoot at my apartment using direct-on flash (set to full power) to see how far it'll illuminate the picture.

but was shocked to see that even at ISO 100, the noise looks worse off than any P&S.

picture was taken raw, RAW-converted with CS2's parameters set to 20D's suggested settings.

The image appears to be severely underexposed which would be the likely reason for the noise. Even the closest portion of the building was too far away to be illuminated properly by the Speedlite.

This it exactly what happens when you underexpose the picture a lot. I assume you raised the exposure in Camera Raw, and that is the cause of the noise.

Next time try putting the camera on a tripod and using a longer exposure, it may look nicer .

I agree with the others...underexpose a pic by this amount and you'll get noise no matter the ISO setting.

yes, put back my CF into the 20D again and previewed this picture, the histogram shows only one line on the leftmost and nothing else. but how come CS2 attempts to "guess" and in this case, "overcorrects" this exposure by "pulling" the histogram towards the centre by so much?

ok, so this is a case of a defective user rather than a defective camera. thanks all

It sounds like you also have the auto correct functions turned on in CS2. I would suggest you turn those off and adjust it yourself.

bingo! u hit the jackpot!!! CS2's Auto Adjustment in RAW Converter is enabled...

Turning that off was the first step after installation...

Titus213 wrote in post #3468367
It sounds like you also have the auto correct functions turned on in CS2. I would suggest you turn those off and adjust it yourself.

Yeah, i second that. The auto correct function can give you a false sense of security sometimes...

Rob