Bayer close to limit, Foveon just started?

Started Sep 21, 2010 | Discussions thread
Eric Fossum
Contributing MemberPosts: 842
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Re: No, and no...
In reply to Joseph S Wisniewski, Sep 22, 2010

Joseph S Wisniewski wrote:

  • The real advantage of a Foveon sensor was its on-chip binning capability. It has the best, easiest to implement liveview and video modes of any sensor ever built. But that was 2002. In 2008, Canon launched Bayer sensors with horizontal binning, and this year we're going to see a lot of Bayers with both horizontal and vertical binning.

I have a hard time believing that this was the real advantage of Foveon. This is not a fundamental thing at all, unless you are trying to bin before the ISP. Why would anyone do that unless their ISP was a massive power hungry (or slow) processor?

  • Bayer sensors don't have a lower limit on color accuracy, they can achieve literally perfect (100% match to human eye perception) color. Foveon sensors have a lower limit of 6% color errors due to failure of observer metamerism.

Indeed, the spectral response of the silicon 3-layer structure is fundamentally different from the human eye's response. It is only thru massive computing that the color comes out as well as it does. To me the color quality of the Foveon-type sensor is right there with a 747 leaving the ground in terms of technical amazement.

In short, this new camera is interesting because it dares to push the pixel count so high. No one has tried an equivalent 30mp Bayer yet.

I don't understand this statement. Of course "Bayer pattern" sensors, both CCD and CMOS, have far exceeded 30 mpixels. Perhaps you had another point in mind, or perhaps you were talking about cameras under, say, $5000.

Aside from my usual nitpicking, the degree to which the Foveon hype and slight disinformation has stuck in the heads of some photographers astounds me, so I am glad that you have taken the time to respond some of the participants in this forum in a relatively patient way.

Lastly, for a 5 um pixel, the spectral response of the Foveon pixel is going to depend fairly strongly on ray angle. I also expect read noise (low light performance) to be rather poor compared to the "equivalent" Bayer pixel. I wonder how this will all pan out in practice.

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