Originally posted by ryan s Ben, I actually held them both side-by-side and couldn't detect any difference
I wish it was at C's 40D dB level because it's just a "click".
Hm, I have both cameras here, side by side and tried a comparisson again. The effect is as follows. If I trigger the shutter (all settings the same with MF, M-mode at 1/250s) they produce exactly the same noise (level and spectrum, but not measured, just aural) IF I listen from above. (Obviously the cameras are not placed on a table or any other resonating rest, but held in my hands).
IF I turn the cameras so, that I "listen" from the back, quite as I do while shooting, the K20 is considerably quieter, as if dampened somehow. It might be the bigger LCD with the according electronics layer. Switching SR on or off has a slightly detectable influence in the K10, where SR makes a grinding, hard noise, but not in the K20. Listening from the front, the K20 is also quieter, just as from the back.
Nevertheless, the K20 is noisier than a EOS 40D or the like.
I can't claim, that this is a comparisson, which can be generalized. It might be, that I have a particularily noisy K10 or a particularily quiet K20. I also use the battery grip + a large QU plate on both cameras, which certainly have influence the noise level ans especially the spectrum.
Ben