This is probably a very stupid question, but I'm asking it anyway: if one sees the superb results that the full-frame sensor of the 5D mk II delivers, why on earth have camera makers been producing professional cameras with 3 mini (2/3 inch!) chips all these years? Full-frame CMOS chips exist since at least a decade, but still Sony and the likes keep launching pro-cams with three miniature chips, instead of one BIG sensor. Why? Better colour control?

1. It is only recently that it has been possible to pull the data off the big D-SLR chips fast enough to do video.

2. On a filtered single sensor, you are throwing 2/3rds of your light away. The three way beam-splitter that the video folks use is more expensive, but more light sensitive way of doing the color separation.

3. The size, cost, and weight of a 10x - 20x power zoom, autofocus 35mm lens would be high. Your ability to hand carry it and shoot hand held for any length of time could be very low.

4. While the film makers are going wild for the shallow depth of field of the big sensor D-SLR cameras, the mere mortals among us note it is a lot easier to hit focus with the smaller chipped cameras.

Those are the reasons that come off the top of my head.

That all makes sense. Thanks for enlightening me, Bob. One mystery less.

The 3 chippers are also mostly/all CCD not CMOS, so no jello.