Sigma/Foveon Questions
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From: Alfred Molon on 1 May 2010 10:46 In article <010520100556079051%nospam(a)nospam.invalid>, nospam says... > bayer doesn't cut off at 1/2 nyquist. The big problem with bayer is that luminance and chrominance have different resolutions (chroma half of luminance). If you dimension the AA filter for the luminance you end up with colour moire, if you dimension the AA filter for the chrominance you have no moire but lose resolution. A full colour sensor does not have this problem. -- Alfred Molon ------------------------------ Olympus E-series DSLRs and micro 4/3 forum at http://tech.groups.yahoo.com/group/MyOlympus/ http://myolympus.org/ photo sharing site
From: nospam on 1 May 2010 11:18 In article <MPG.26465d38428402f698c2cb(a)news.supernews.com>, Alfred Molon <alfred_molon(a)yahoo.com> wrote: > The big problem with bayer is that luminance and chrominance have > different resolutions (chroma half of luminance). so does the human eye. chroma is 1/10th of luminance, so bayer actually has more than the eye can resolve. it's not a problem. > If you dimension the > AA filter for the luminance you end up with colour moire, if you > dimension the AA filter for the chrominance you have no moire but lose > resolution. there's more to it than just that. > A full colour sensor does not have this problem. true, but sigma skips the aa filter entirely which is an even bigger problem.
From: Ray Fischer on 1 May 2010 13:05 Doug McDonald <mcdonald(a)scs.uiuc.edu.remove.invalid> wrote: >On 4/30/2010 11:56 PM, Ray Fischer wrote: >> Alfred Molon<alfred_molon(a)yahoo.com> wrote: >>> By the way, nospam, do you realise that a Bayer sensor has an additional >>> issue: sensitivity. Each pixel only captures either red, green or blue >>> photons, thereby throwing away 2/3 of the incoming light. >> >> Do even know why that's a silly statement? > >That's not silly! Its important! No, it isn't. What's important is what you do with the light that you get. Eliminate all that glass and diaphram and camera body that blocks all that light, eliminate the color filters and all the space between sensels and you'd get a lot more of the light. And for a phometry experiment that'd be useful but you wouldn't get an image. >In case you didn't know, professional video cameras don't use Bayer. In case you didn't know, professional video cameras have much, much lower resolution than even compact still cameras. Good thing, too, since aligning three high-resolution sensors would be difficult and very expensive and bulky and delicate. >They use three sensors, one for each color, and dichroic color >separation filters that, if well made, lose almost no light at all. Your obsession with "losing light" is ... odd. >The absorptive filters in a Bayer filter lose quite a bit of light Who cares? Stick a fast lens in front. -- Ray Fischer rfischer(a)sonic.net
From: Alfred Molon on 2 May 2010 03:53 In article <010520101118269360%nospam(a)nospam.invalid>, nospam says... > so does the human eye. chroma is 1/10th of luminance, so bayer actually > has more than the eye can resolve. it's not a problem. You are mixing up things. Besides the human eye is *not* the reference. For instance, the human eye cannot see colours at night. According to your logic, camera sensors should switch to black and white at night. -- Alfred Molon ------------------------------ Olympus E-series DSLRs and micro 4/3 forum at http://tech.groups.yahoo.com/group/MyOlympus/ http://myolympus.org/ photo sharing site
From: nospam on 2 May 2010 04:06
In article <MPG.26474df14f77f73c98c2cc(a)news.supernews.com>, Alfred Molon <alfred_molon(a)yahoo.com> wrote: > > so does the human eye. chroma is 1/10th of luminance, so bayer actually > > has more than the eye can resolve. it's not a problem. > > You are mixing up things. Besides the human eye is *not* the reference. if someone is taking photos to be viewed by humans, then it *is* the reference. if you can't see it, then there's no need to capture it. |