Was the Foveon limited in funding to further develop or was it a technical physics stop?
While the Foveon is a quite an interesting technical achievement, it is not without some serious problems for high quality imaging. One of the major obstacles is that the color separation by penetration depth in silicon, delivers an almost monochrome rendering of the scene. It requires huge color separation factors to split the data into R/G/B planes. That separation process comes with an increase of noise, and the fill factor of the sensels is already low to begin with. Another problem is that penetration depth of silicon varies with the angle of incidence, so larger sensors will require even more heavy lifting in postprocessing to somewhat mitigate the adverse color pollution cause by oblique rays.
Besides that, as mentioned, without AA-filter the Foveon will also suffer from luminance moiré. Because R/G/B is sampled at approx. the same position, false color aliasing artifacts are less of an issue.
Also, sampling 3 color planes per sensel will also triple the uncompressed file size compared to Bayer CFA Raw data. That will require more processing power in camera (and more battery capacity), more storage space, and takes longer to record (lower number of images per second). It will also be slow in Raw conversion, and there may be little Raw converter support other than from the manufacturer themselves.
Canon have patents for quite different technology that also allows to capture R/G/B per sensel, but they are not likely to use that any time soon (complex/expensive to produce and proprietary Raw conversion needed), if ever. The Bayer CFA still has lots of potential, and it seems (if the rumors are true) that accurate color is the preferred approach for the 5Ds (s is for studio). That will be possible if more selective band-pass filters are used (hence the modest ISO claims), the opposite of the hugely overlapping Foveon color planes. Maybe a future addition of a 4th color (e.g. Yellow) in the filter array can help to get even better color, especially if sensel pitch keeps shrinking.
Cheers,
Bart
