Moire in Canon A590

Discussion in 'Canon' started by Peabody, Nov 5, 2009.

  1. Peabody

    Peabody Guest

    Today I tried to take a picture of the strings of a grand piano,
    from the back end, and got a significant moire pattern in the area
    where the bass strings lie above the treble strings, but are strung
    in different directions. This criss-cross area looked pretty bad.

    Is there anything I can do to reduce or eliminate this effect? Any
    camera setting that I could select?

    Would a better camera do better in this situation, or is it just
    physics? Does the A590 not have any low-pass filter to reduce this
    aliasing problem?
     
    Peabody, Nov 5, 2009
    #1
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  2. Peabody

    Info Man Guest

    Turn down the in-camera sharpening to the lowest level. Might help to turn
    down contrast to lowest level too. You will also avoid that by simply
    changing the angle of your sensor to the angle of the moire'-causing
    subject. You can rotate later in post-processing (use Lanczos-8 resampling
    algorithm if available for rotations and resizing).

    Do those sharpening and contrast phases in post processing. I never let any
    camera handle those to any degree if it allows for it.
     
    Info Man, Nov 5, 2009
    #2
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  3. You will always be able to get moire effects when viewing images at
    less than the meximum size. The camera's anti-aliasing filter only
    applies to its maximum resolution.

    Do you still see this effect on the maximum full size image?
     
    Chris Malcolm, Nov 5, 2009
    #3
  4. Peabody

    Peabody Guest

    Chris Malcolm says...
    Well, using the full 8MP, and viewing the pic on my biggest
    monitor, the moire is almost completely removed. Actually,
    the problem may have been more in the display medium than in
    the picture itself. The smaller the display, the more
    the moire shows up. Review on the camera itself is
    particularly bad.

    I hope that means it won't show up in prints.

    Thanks for your help.
     
    Peabody, Nov 5, 2009
    #4
  5. Peabody

    Bob Larter Guest

    You have that backwards. Canons have *strong* antialiasing filters, &
    tend to benefit from a bit of sharpening when processing from RAW.
     
    Bob Larter, Nov 5, 2009
    #5
  6. Peabody

    Peabody Guest

    bugbear says...
    Well, it has a contrast setting for taking the picture, but
    not one for adjusting contrast after the fact.

    So it lets you adjust contrast, sharpness and saturation. I
    assume these are just settings for jpeg conversion, and
    don't affect how the exposure itself is actually made.
     
    Peabody, Nov 5, 2009
    #6
  7. Peabody

    Info Man Guest

    I'm not personally familiar with the A590, but if it has the typical
    Powershot "Custom Colors" setting, you can find it there. Turn down
    sharpening, contrast, and the red channel to -2. That is the most accurate
    sensor to JPG rendition I have found in the Powershot series, that which
    matches the RAW data from that line of cameras. I use a different model of
    Powershot with this "custom colors" feature and never take it off of those
    aforementioned settings.

    If your Powershot does not have that "custom colors" adjustment feature, I
    guess it amounts to buying savvy. All the P&S cameras that I buy have both,
    sharpening and contrast adjustment.

    High contrast on the resulting JPG files in many consumer level cameras is
    set inordinately high. The Nikon cameras being the absolute worst in this
    regard. This is due to marketing where people expect an eye-popping image
    right from the camera no matter the lighting conditions. I don't buy a P&S
    camera unless it is renowned for its low contrast or has an option to turn
    it as low as possible. The low-contrast cameras take full advantage of the
    sensor's dynamic range to where there is rarely any need to obtain any RAW
    data from the sensor. Sony cameras in the past used to be well known for
    this lower contrast output (which I admired for their decision from a pure
    photographer's standpoint), which sadly sharply cut into their sales due to
    the vast inexperience of the snapshooting masses. The full dynamic range of
    the sensor is reflected in those cameras' JPG output which innately have
    low-contrast JPG output, or where it can be turned down.
     
    Info Man, Nov 5, 2009
    #7

  8. Bob Larter's legal name: Lionel Lauer
    Home news-group, an actual group in the "troll-tracker" hierarchy:
    alt.kook.lionel-lauer (established on, or before, 2004)
    Registered Description: "the 'owner of several troll domains' needs a group where he'll stay on topic."

    <http://groups.google.com/groups/search?hl=en&num=10&as_ugroup=alt.kook.lionel-lauer>

    "Results 1 - 10 of about 2,170 for group:alt.kook.lionel-lauer."
     
    Bob Larter is Lionel Lauer - Look it up., Nov 5, 2009
    #8
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