Originally posted by luck1 Foveons chip per pixel sharpnes is so huge, it is limited by the lens + the color output is superb, thanks to its technology. The only problem is its high ISO performance
Actually, color output is Foveon's achilles' heel. With a Bayer-style sensor, the color filters over each photosite can be specified with pretty much whatever precision is desired. With Foveon, the distinction between the different colors is due to the different light-absorbing properties of silicon, and while clever, it turns out to be less than ideal.
Specifically, each color sensor picks up a wider spectrum than ideal, and not exactly tuned to the pure red, green, and blue used in normal RGB colorspace. Straightening all of this out means loss of signal, so you get noisier high ISO. Worse, though, you get strange color shifts.
One site with examples (from the DP1):
Ian Bogost - Technical Evolution and Creative Constraint
Advances in Foveon technology might help to some degree, and of course going full frame would give another stop of light gathering without increasing ISO, but since the problem is basically intrinsic to the design, I wouldn't bet my camera company's future on it. (Sorry, Sigma -- at least you've got the third-party lens market.)
I'm all for more interesting sensor designs, though. I think the Bayer-like patterns which include "clear" photosites are definitely interesting, and we may -- especially as wide-gamut displays become more common -- see a return of arrays which include more different colors. (Like Sony's red-green-blue-emerald.)
Last edited by mattdm; 07-02-2010 at 12:08 PM.