One of the misconceptons is that 3 CCD chipset has better low light sensitivity than a single CCD. This is not the case. There is certain amount of light coming from the lens and in a 3CCD system you split it into 3. Overall the same amount of light is reaching the chips.

3 chip CCD system has more accurate colors. You pick up luminance and the complimentary colors at the same time in the same point during the scan. In 1 CCD system there is a shift among the 3 signals.

For RGB signal 3 CCD's are a must, for 4:2:2 comression there is a significant improvement with 3 CCDs. For 4:1:1 one CCD is fine.

"Overall the same amount of light is reaching the chips. "

Since there's always some transmission loss in a medium (the mediums in this case being a prism and a color filter), one should find the effective ASA of a three-chip camera is reduced by the splitting--i.e., less light reaches the CCDs than with a CFA 1-chipper. (Of course it could be a nominal amount in comparison to other factors: the optics, the iris, etc.)

The loss in the prism is minimal. The 3-chip camera has 3 filters; the 1-chip camera has individual filters one ach pixel.

I think the future will be single CCD designs. Canons CMOS chip in the EOS 10D is a 6 Mega pixel chip that gives 35mm film quality up to about 16 X 20. That camera cost $1,500 and Canon makes their own CMOS chip. If they applied a little of that technology to the next generation XL series, just imagine what we might be shooting.

In still photography 1 CCD is fine. You read the RGB pixels, store that information and print that information. With moving images you use more compression. If you sense in RGB, record in RGB, and play in RGB, one CCD would be fine. The way they process the color signal, by recording one lumimnace signal and 2 compressed color components, the 3 CCD have an advantage, because at any instance you read 3 colors and from that you create the 3 signals. With one CCD you can't read the colors simultaneously. So unless you get to CineAlta SR with 4:4:4 RGB stream, 3 CCDs are an advantage.