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Author Topic: Anti-aliasing filter in 1DX  (Read 6421 times)

Aglet

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Re: Anti-aliasing filter in 1DX
« Reply #15 on: April 04, 2012, 02:45:00 PM »

Now I'm confused :(

What would be the advantage of having a different version of the D800 without a low pass/AA filter then? I somehow gained the impression that it was for e.g. landscape photographers who want more detail in their images. If absence of a filter generates false detail/is destructive to detail, what would be the advantage of leaving the filter off?

slight improvement in sharpness but run into the effects of moire.  Nikon site has a blurb on it.

http://imaging.nikon.com/lineup/dslr/d800/features01.htm

also had a good comparison of D800 vs D800E and the moire effect in things like fabrics vs landscape

http://en.nikon.ca/en_CA/o/CBTZ8ZQ3AzZ4Pm9E2GAU8EKdTa4/PDF/Moire_and_False_Colour.pdf

New Fuji X-1 pro (?) is using non-Bayer type sensor to supposedly eliminate moire without using an AA filter.  "inspired by film."

www.fujifilm.ca/products/digital_cameras/x/fujifilm_x_pro1/features/page_03.html

.. which might be an interesting alternative to non AA-filtered Bayer sensors or Foveon.

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Re: Anti-aliasing filter in 1DX
« Reply #15 on: April 04, 2012, 02:45:00 PM »

jrista

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Re: Anti-aliasing filter in 1DX
« Reply #16 on: April 04, 2012, 08:02:14 PM »
Thanks for all the background info provided here. A few more questions:

Is this problem less pronounced in CCD sensors? As far as I know the Leica M9 doesn't have such a filter and I still think that it's one of the cameras that delivers the best results of them all (I don't have one and there may be other factors at play including the lenses).

A lot of that is psychological...there is a hard-core subculture of Leica fans, similar to the hard-core subculture of say Apple fans. Apple stuff is nice, but it is not necessarily "the best", and a significant factor of its success is the psychological impact of Apple's advertising and presentation (they really do excel at making people want their products, regardless what the product is.) There is also plenty of information on the net about professional photographers who have complained about moire and aliasing with their incredibly expensive Leica cameras. A couple google searches should bring all that to the surface. Don't get me wrong, Leica cameras are certainly excellent...however they are by no means perfect, there are issues with the lack of an AA filter, and the gap between Leica and regular old DSLR's has certainly shrunk with the advent of the D800 (and even the 5D III, which is still a very high resolution camera.)

Also, wouldn't it be possible to leave out the filter and deal with any moire effects in post? Or would it be possible to arrange the photosites more randomly? I'd like to see something that was more along the lines of film grain anyway...

You can always try to fix things in post, but no amount of post-process work can ever really entirely restore what you may have lost initially. Lightroom 4's new Moire removal tool is pretty nice, but it is not perfect, and can only do so much.

As for arranging photosites randomly, certainly! Thats essentially how the retina's of our eyes work, with an entirely random distribution of luminance and chrominance sensing structures. Trying to manufacture something similar, however, would be much harder than manufacturing something with a simple, repeated pattern. The design of such a CMOS decide would be incredibly complex, and one would have to wonder exactly how it would be done at all (How would you handle "row" and "column" activate? Could you even do row and column activation? How do you parallelize readout if you can't? How would random distribution affect current flow and electronic noise? What is the smallest density you could achieve? etc.) There may be some ways to achieve such a thing while still using a grid-based pixel layout, called Digital Film System. There are plenty of challenged with that approach as well.

Randomizing distribution should certainly resolve the issue though, as moire is the interference pattern generated when similar repeating patterns interact in a non-ideal way. Eliminate one of the repeating patterns, and the effect should disappear.
« Last Edit: April 04, 2012, 08:13:59 PM by jrista »

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Re: Anti-aliasing filter in 1DX
« Reply #16 on: April 04, 2012, 08:02:14 PM »