09-22-2010, 04:40 PM
[quote name='wim' timestamp='1285160794' post='3091']
Well, I don't agree. Previous Foveon sensors had an (optimistic) advantage of about 30% to 40 % when deFoveonised, i.e., Foveon MP divided by 3. That would put it roughly in the 20MP ball park compared to Bayer sensors (46MP / 3 * 1.3), or up there approximately with the 18 MP Canon sensor.
We'll have to wait for the first test results, however, to see how it really performs.
Kind regards, Wim
[/quote]
Let's take a simple best-case for foveon. Say you're shooting a highly detailed blue subject. Only 1/4 of the sites on a bayer sensors can detect blue*, whereas a whole layer of sensors on the foveon will. The 18MP Canon sensor only has about 4.5M blue detectors, compared to around 15M in the new Sigma.
*assuming perfect colour filters, I know that isn't the real case.
Green might in theory show the least difference, but the AA filter almost certainly means you would never get the expected improvement from the increased number of green sites.
The diffraction impact will also kick in earlier on the foveon... that might limit the apparent sharpness at what were previously considered "good" apertures. Even f/5.6 is probably in the diffraction softening zone on this Sigma.
Well, I don't agree. Previous Foveon sensors had an (optimistic) advantage of about 30% to 40 % when deFoveonised, i.e., Foveon MP divided by 3. That would put it roughly in the 20MP ball park compared to Bayer sensors (46MP / 3 * 1.3), or up there approximately with the 18 MP Canon sensor.
We'll have to wait for the first test results, however, to see how it really performs.
Kind regards, Wim
[/quote]
Let's take a simple best-case for foveon. Say you're shooting a highly detailed blue subject. Only 1/4 of the sites on a bayer sensors can detect blue*, whereas a whole layer of sensors on the foveon will. The 18MP Canon sensor only has about 4.5M blue detectors, compared to around 15M in the new Sigma.
*assuming perfect colour filters, I know that isn't the real case.
Green might in theory show the least difference, but the AA filter almost certainly means you would never get the expected improvement from the increased number of green sites.
The diffraction impact will also kick in earlier on the foveon... that might limit the apparent sharpness at what were previously considered "good" apertures. Even f/5.6 is probably in the diffraction softening zone on this Sigma.
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