Sigma/Foveon Questions
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From: Alfred Molon on 1 May 2010 04:58 In article <4bdbe55f$0$22779$afc38c87(a)news.optusnet.com.au>, dj_nme says... > If it followed the current Sigma and Foveon image sensor design > practice, it would be missing an anti-aliasing filter and produce > mountains of moire (false detail and "stair stepping")that would kill > the alleged "advantages" that you are hoping for. Can't comment on this, but obviously any camera needs a clean cutoff at the Nyquist frequency. The advantage of a full colour camera is that it doesn't have to cutoff at 1/2 the Nyquist frequency. -- 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 05:56 In article <MPG.26460baf2f2e3fe398c2ca(a)news.supernews.com>, Alfred Molon <alfred_molon(a)yahoo.com> wrote: > > If it followed the current Sigma and Foveon image sensor design > > practice, it would be missing an anti-aliasing filter and produce > > mountains of moire (false detail and "stair stepping")that would kill > > the alleged "advantages" that you are hoping for. > > Can't comment on this, but obviously any camera needs a clean cutoff at > the Nyquist frequency. actually, a little before nyquist, but he's right, foveon images are full of false detail and moire patterns. > The advantage of a full colour camera is that it doesn't have to cutoff > at 1/2 the Nyquist frequency. bayer doesn't cut off at 1/2 nyquist.
From: David J Taylor on 1 May 2010 06:43 > I also wouldn't buy the Sigma 4.6MP camera, because it does not have > enough pixel count. But if there was a 12MP Foveon camera, it would > (roughly) be on par with an 18MP Bayer camera. And those 12MP would be > real pixels, not fake Bayer ones. No more weird Bayer images with no > real resolution at the pixel level. > > I would have a closer look at such a camera and check its overall > performance and features and consider buying one if it matches my needs. > -- > > Alfred Molon For the final image, I don't think I care in the least bit where the pixels come from, be it Bayer or Foveon, providing the end result is good enough, and that's the key. I've not had significant bother with "fake pixels" or "weird Bayer images" in my own photography, though. Cheers, David
From: Doug McDonald on 1 May 2010 10:04 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! In case you didn't know, professional video cameras don't use Bayer. They use three sensors, one for each color, and dichroic color separation filters that, if well made, lose almost no light at all. The absorptive filters in a Bayer filter lose quite a bit of light in each color except red, not to mention the loss due to haveing each sensor site get only one color. The tradeoff, of course, is having to use extremely expensive lenses that have a large back focal length and special design so that the image gets correctly through the dichroic cube prism (or mirrors). Doug McDonald
From: nospam on 1 May 2010 10:25
In article <hrhc9d$bep$1(a)news.acm.uiuc.edu>, Doug McDonald <mcdonald(a)scs.uiuc.edu.remove.invalid> wrote: > In case you didn't know, professional video cameras don't use Bayer. yes they do. <http://www.red.com/> > They use three sensors, one for each color, and dichroic color > separation filters that, if well made, lose almost no light at all. that is not suitable for a still camera, and now video cameras too. |