09-22-2010, 10:39 PM
[quote name='popo' timestamp='1285173651' post='3096']
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.
[/quote]
My note was based on previous Foveon sensors and comparisons of test shots. The thing is that the Foveon actually still only has 1/3 of the number of actual sensels or pixels indicated by Sigma, just that they can read the full spectrum. And this gives them a slight edge over Bayer sensors, as I mentioned, in the past anyway, of about 30 % to 40 % over their actual number of sensels, but certainly nothing like 3X that.
Regarding diffraction and sensors: I won't go into this, except maybe for a thread specifically dealing with that. Let me just note here that we never talked about diffraction limits with film and halide grains, so why should we all of a sudden with sensors. In my book it is a total non-issue, except for engineers specialized in this subject <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' />.
Kind regards, Wim
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.
[/quote]
My note was based on previous Foveon sensors and comparisons of test shots. The thing is that the Foveon actually still only has 1/3 of the number of actual sensels or pixels indicated by Sigma, just that they can read the full spectrum. And this gives them a slight edge over Bayer sensors, as I mentioned, in the past anyway, of about 30 % to 40 % over their actual number of sensels, but certainly nothing like 3X that.
Regarding diffraction and sensors: I won't go into this, except maybe for a thread specifically dealing with that. Let me just note here that we never talked about diffraction limits with film and halide grains, so why should we all of a sudden with sensors. In my book it is a total non-issue, except for engineers specialized in this subject <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' />.Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....