Bayer aliasing on the 5D

Discussion in 'Digital Photography' started by Alfred Molon, Jan 28, 2006.

  1. Alfred Molon

    Alfred Molon Guest

    Alfred Molon, Jan 28, 2006
    #1
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  2. Nothing is apparent from this post. I think I see Moiré (an assumption on
    my part). I see no information from David. I even messed with the URL to
    find David's comments. I'd appreciate some more information from you.
     
    Charles Schuler, Jan 28, 2006
    #2
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  3. =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?=, Jan 28, 2006
    #3
  4. It looks like the picture might have been taken through a window screen.
     
    Peter A. Stavrakoglou, Jan 29, 2006
    #4
  5. Nothing, other than about Alfred, I agree.

    Maybe Alfred knows (which I doubt) what type of Raw converter was
    used?

    Bart
     
    Bart van der Wolf, Jan 29, 2006
    #5
  6. Alfred Molon

    Steve Wolfe Guest

    Apparently the AA filter of the 5D is inadequate.

    Yeah, and if it were stronger, people would complain that the camera
    sacrificed resolution. Someone will always complain about something.

    teve
     
    Steve Wolfe, Jan 29, 2006
    #6
  7. Exactly. I'd prefer 16MP and the 5D's AA filter or maybe even a slightly
    stronger one, but Canon was obviously eyeing the Nikon D2x*, which has
    essentially no AA filter. Even with the rather weak AA filter in the 5D, one
    of the first reviews found the D2x to "capture more detail", even though all
    it was doing was misrepresenting that detail (funny how it kept finding
    grids at exactly the same frequency as the pixel pitch). Sigh. The 5D
    requires strong contrast at somewhat over 40 lp/mm to show Moire, whereas
    the D2x requries strong contrast at somewhat over 60 lp/mm to show moire.
    Since lenses have much lower contrast at 70 lp/mm than 50 lp/mm, the D2x is
    going to have much less Moire problems. Heck, most lenses will only produce
    over 70 lp/mm at strong contrast at their optimal f stop.

    *: There were a couple of 5D vs. 1Dsmk2 tests on the web, and to the best I
    could tell, the 1Ds simply doesn't capture any more detail (part of this may
    have been the stronger AA filter, but a lot of it is that the 14% increased
    linear resolution just isn't all that much). Presumably Canon understood
    this, and wanted the only difference between the 5D and the D2x to be noise
    and dynamic range. (I.e. they didn't want to be told by various idiots that
    the D2x resolves just as much as a 16MP camera.)

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Jan 29, 2006
    #7
  8. Alfred Molon

    Mark² Guest

    Mark², Jan 29, 2006
    #8
  9. Alfred doesn't. It looks pretty much the same whatever RAW converter you
    use. That crop is from RSP, but DPP looks similar, and I emailed the RAW to
    someone who uses dcraw and their own homebrew, and they didn't see anything
    particularly different.

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Jan 29, 2006
    #9
  10. Alfred Molon

    Ray Fischer Guest

    Ray Fischer, Jan 29, 2006
    #10
  11. Alfred Molon

    Alfred Molon Guest

    Hi Ray,

    the AA filter is necessary to reduce the high frequency content below
    the Nyquist frequency, prior to sampling, otherwise there will be
    sampling errors:
    http://en.wikipedia.org/wiki/Aliasing

    "[Aliasing] is also a major concern in digital imaging and computer
    graphics, where it may give rise to moiré patterns (when the original
    image is finely textured) or jagged outlines (when the original has
    sharp contrasting edges, e.g. screen fonts). Anti-aliasing techniques
    are used to reduce such artifacts."
     
    Alfred Molon, Jan 29, 2006
    #11
  12. Alfred Molon

    Alfred Molon Guest

    I have no more information about the image than you have, but moiré is
    caused by aliasing:
    http://en.wikipedia.org/wiki/Aliasing

    Aliasing is caused by sampling a non properly filtered signal. Not sure
    what role the RAW converter (if a RAW converter was used) plays.
     
    Alfred Molon, Jan 29, 2006
    #12
  13. Alfred Molon

    Alfred Molon Guest

    It's not my image, but it looks that the aliased parts contain a fine
    metal grid.
     
    Alfred Molon, Jan 29, 2006
    #13
  14. What kind of needless Nikon bashing is this?

    Compare dpreview's resolution test of the D2X with that of the 1DS mk II
    (in the D2X test) and you will see very similar artifacts.

    (The same test shows what a missing AA filter really looks like)
     
    Philip Homburg, Jan 29, 2006
    #14
  15. Alfred Molon

    rafe b Guest


    Maybe that group includes yourself, eh?

    What do *you* think it's supposed to do, Ray?

    Fact is, there are both strong and weak AA
    filters (it's always relative to the underlying
    sensor, of course). Strong ones will make the
    camera appear less sharp. A weak one will
    make the camera appear more sharp, but will
    introduce artifacts and false detail.


    rafe b
    www.terrapinphoto.com
     
    rafe b, Jan 29, 2006
    #15
  16. Alfred Molon

    Steve Wolfe Guest

    Exactly. I'd prefer 16MP and the 5D's AA filter or maybe even a slightly
    I think that you're being overly sensitive. If you bothered to read the
    rest of his message, you'll find that he went on to explain that the D2X
    captures a very large amount of detail, with very little moire problems. In
    fact, he said that the 1Ds Mk2 doesn't seem to capture any more detail than
    the D2X. I can't see anything negative there, let alone bashing, so maybe
    you got your shorts tied in a knot for nothing.

    steve
     
    Steve Wolfe, Jan 29, 2006
    #16
  17. You may want to try, if possible, the new Adobe Camera Raw Version
    3.3. It has much better aliasing suppression than the previous
    versions, and pulls out a bit more detail at the same time.

    Bart
     
    Bart van der Wolf, Jan 29, 2006
    #17
  18. Alfred Molon

    Rich Guest

    What was the target that caused it, it looks like a screen or was it
    just a window?
    -Rich
     
    Rich, Jan 29, 2006
    #18
  19. I think it's a railing on a walkway with vertical supports. (It is the worst
    I've seen, but it's definitely an issue. Fortunately, it doesn't show up in
    nature shots, and isn't all that common. As I mentioned before, it's all
    Nikon's fault. And the idiot Foveon fans.)

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Jan 30, 2006
    #19
  20. Alfred Molon

    rafe b Guest


    Just smear a little Vaseline on the lens.
    Works for Bob Guccione.


    rafe b
    www.terrapinphoto.com
     
    rafe b, Jan 30, 2006
    #20
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