Originally posted by Anastigmat If the K20D uses a 14mp APS-C sensor, the laws of physics would dictate that its high ISO noise level is going to be worse than the 10mp K10D. Only by increasing sensor size to full frame can a 14mp camera be expected to have low noise at the current stage of evolution of sensor technology. People do not need to pay thousands more for a full frame DSLR. They only need to pay a few hundred dollars more. Full frame DSLR cameras, if and when they fall below $2,000, will become mainstream and begin to replace APS-C cameras in the market place.
We'll see about the law of physics vs. technology in a few weeks...
However, why should the FF, even falling in price, ever replace APS-C?
I know that FF IQ is better at a given number of pixels and that there are some things that a FF can do that an APS-C cannot but I think that, as of today, it would be very difficult to tell an image taken by a 5D from an equivalent image taken with, say a 40D when printed up to 40x60cm.
You have to go more and more to the details, or specialized needs, nowadays to truely give FF an advantage.
I don't see the need for the general public (I count myself in that category of course), to pay, even a few hundreds more as you put it to get some improvements that are likely not to be discernable in prints smaller than 40x60cm.