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Moire? First time for me....

Discussion in 'General Technical Discussion' started by Butlerkid, Jan 11, 2019.

  1. Butlerkid

    Butlerkid Cafe Ambassador Moderator

    Apr 8, 2008
    Rutledge, Tennessee
    Karen
    Since I don't photograph people, clothing or fabrics.....I'd never given moire much thought. I knew what it was and what it looked like.

    From the Nikon website:
    "Sometimes odd stripes or colors will appear in a digital image, either from a high-end digital camera, or from a scanned image. This effect is called moiré and is caused when a fine pattern in the subject (such as the weave in a fabric or very close, parallel lines in architecture) matches the pattern of the imaging chip. When two patterns meet, often a third, new pattern is created. This third pattern is called moiré. Notice in the illustration below the round, circular patterns (on the right) created as the two grids are combined; this is moiré.

    moire_forms.gif
    Subscribe to see EXIF info for this image (if available)


    In order to reduce (or eliminate) moiré, a special anti-aliasing filter is mounted in the camera. If too strong a filter is mounted an overall soft image will be produced, but with no moiré. If a weaker filter is chosen the image will be sharper, but there is more of a chance for moiré to happen in some circumstances. Nikon has chosen to produce the sharpest image that can be made, even though there may be some moiré in parts of some images."

    But moire wasn't something I ever had to deal with. Until I processed this photo of a parrott....full frame using my new 600mm that I was testing for focus accuracy and sharpness!

    On my monitor there is very strong moire in most of the blue feathers in the middle and lower left corner. When I zoom in 100% they are barely visible. And - surprise! When I inserted the image below from my SM website, the moire pattern is hardly visible ....and only slightly more visible on my website.

    _KD57076-X3.jpg
    Subscribe to see EXIF info for this image (if available)


    I photographed a lot of highly detailed feathers, but never encountered this before.
     
  2. Welcome to the world of "Longest" glass. Your 600mm is showing more detail and that detail has some Morie in it. With the 800mm having a little Morie in flight feathers is normal especially when viewed at 100%.
     
  3. Very nice pix on your site !
     
  4. Butlerkid

    Butlerkid Cafe Ambassador Moderator

    Apr 8, 2008
    Rutledge, Tennessee
    Karen
    So longer glass is more susceptible to moire? My only shots with the 1.4 tele so far have not been of finely detailed feathers such as those on the parrot above. I used the 1.4 tele quite a bit on the 500.....especially with hummers, etc. and never noticed moire. Maybe it was there and I missed - or maybe it was not there.
    Thanks! Feel free to look around. Lots of different "stuff"! LOL!
     
  5. No. The increase in details at distance the 600 provides is what you are seeing in the flight feathers. Those feathers have repeating straight lines. The biots are uniform and as such subject to morie.
    A sharp 100mm lens used near enough should give you the same result.
     
  6. Butlerkid

    Butlerkid Cafe Ambassador Moderator

    Apr 8, 2008
    Rutledge, Tennessee
    Karen
    Have you found an effective way to minimize the moire in photographs after they are taken?
     
  7. Beautiful photo Karen, and what a stunning bird. Wish I could offer a suggestion for the moire, but I’ve never had it happen.
     
  8. PSCC. You can paint it in in ACR. Moire reduction and defringe will do it. Used it many times.
     
  9. When downsizing photos, moire that doesn't exist in the full-size image is sometimes produced in the downsized image. My guess is that there is a mathematical formula that can determine the relative size of the downsized photos that won't produce the moire, but I've never looked for it. If anyone can easily point me to that information, I would appreciate it.
     
  10. Considering that you are a woman, I'm surprised that you didn't allow for the explanation that the parrot simply had a bad hair day. :ROFLMAO: 
     
  11. Growltiger

    Growltiger Administrator Administrator

    I have some surprise good news for you. Your photograph is perfect, it does NOT itself have any moiré.

    I know it appears to have moiré and I have no trouble seeing it when I look at the photo, including the one on your website. But what it happening is that when the photo is viewed on a monitor, one sees moiré. The pattern in the photo is conflicting with the pixel pattern on the monitor.

    For a photo to have moiré one needs to have a pattern in the subject conflict with the pixels in the camera's sensor. I see no sign of this once I enlarge the photo on your website sufficiently. If you could post a crop of a bad area near bottom left at 200% I think you will see the fine pattern, but no moiré.

    Here is a example of real moiré created in the camera (with a wide lens). This is a 100% crop of a photo of a fine metal mesh fireguard at an angle.
    02%2012mm%20normal%20crop.jpg
    Subscribe to see EXIF info for this image (if available)


    And this is the same, but photographed at a high resolution so there is no moiré:
    04%2012mm%20hires%20crop.jpg
    Subscribe to see EXIF info for this image (if available)


    The next question is what can you about the moiré that we all see on our monitors?
    1. You could degrade the quality of the photo, which would be very sad.
    2. We could all buy much higher resolution monitors.
    3. You could publish the photo at full resolution but using Zoomify, so we could zoom in online and see the fine detail without moiré (I use Zoomify for panoramas but it would work perfectly for this. I could do this for you if you like.)
    4. You could stop photographing feathers.
     
  12. Butlerkid

    Butlerkid Cafe Ambassador Moderator

    Apr 8, 2008
    Rutledge, Tennessee
    Karen
    Thank you, Richard. Indeed, when I zoomed in to 100% or more I noticed that the moire pattern disappeared! And I wondered about the monitor causing the effect. I did learned that the Adjustment brush in PS has a slider for moire, but it did not have any effect on this image.
     
  13. Butlerkid

    Butlerkid Cafe Ambassador Moderator

    Apr 8, 2008
    Rutledge, Tennessee
    Karen
    When I zoom into the image, there is no moire. I tried the PSCC Adjustment brush and it had no impact on the image.
    I think you are right. Downsizing may very well be causing the issue - and the monitor pixel grid.
     
  14. As an example, on every DSLR my wife and I have used (D50, D80, D5100, D7000), when increasing the magnification of the display in the camera's LCD, every other magnification displays moire when the image content is susceptible to moire. The other magnifications don't display the moire.
     
  15. Growltiger

    Growltiger Administrator Administrator

    That is moiré on the display, not on the sensor. It does not affect the photos.
     
  16. TonyW

    TonyW

    Jan 15, 2010
    UK
    Yes always worth checking that you are not introducing moire artifacts by an inappropriate zoom ratio. I once spent a good amount of time trying to rid an image of moire without success due to me forgetting to check the zoom level in PS :mad: . Moire is just an interference pattern and if your screen grid of pixels happens to fall just right (or rather wrong!) you will see the effect that is not there in the image data and will not show normally or when printed. The big clue is when nothing you do has any effect on the image

    There are several ways (tricks) to tackle moire in post some more effective than others but generally it is not something to obsess about. I think I came across it once or twice with my D800e fairly easily cured in those cases as it was mainly chroma moire and luminance hardly if at all affected
     
  17. Men have bad hair days too o_O 
     
  18. I've found moire a couple of times with certain fabrics. It seemed to change in "intensity" as a picture changed in size. DXO-PL did a dandy job controlling it.
     
  19. I wish I HAD bad hair days.
     
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