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Thread: small tuning problem.

  1. #1
    Join Date
    Nov 2007
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    Default small tuning problem.

    I have my tuning pretty good, but I get a small problem with a few frames. Here is one for example:



    Notice how the 2 smaller guys have a really thin arm on each side, and the big guy has a slightly smaller arm than the other arm. I looked at the frames, and it is normal on there, so it must be some kind of tuning problem. Any hints as to what I should do?
    Thier legs also do it a little bit, but the arms are very noticeable.

    EDIT: Here is another good example. It seems like my X may be running faster than my Y. In that case, what would I have to adjust to fix it?


    Cheers
    Last edited by Things; 10-15-2008 at 05:41.

  2. #2
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    Pflugerville, TX, USA
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    Default

    Could be tuning but my initial thought is that you might be running your galvos too fast or your scan angle is too wide.

    Show us your ILDA pattern, speed, and angle.

  3. #3
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    Default

    It actually looks worse smaller, its running at a pretty big scan angle. I think I need to do some more tuning

  4. #4
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    Lightbulb

    Quote Originally Posted by carmangary View Post
    Show us your ILDA pattern, speed, and angle.
    Ditto... It is hard to see anything without the test pattern.
    Love, peace, and grease,

    allthat... aka: aaron@pangolin

  5. #5
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    Cool

    Post a picture of the ILDA test pattern. Then post a picture of the LaserMedia test pattern. That will go a long way towards troubleshooting the problem. Make sure you are scanning at 8 degrees or less, and at the same scan speed that you normally run.

    Adam

  6. #6
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    Default

    Hi, I am trying to calculate the scan angle, but im abit stuck. At around 2.5metres, how big should the outsde square of the lasermedia test patter be, to give me 8 degree's?

    Thanks

  7. #7
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  8. #8
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    Default

    Hi, ive calculated my scan angle was about 21 degree's. According to the scanpro's manual, at 20 degree's, I can run them at 20K. At 8 degree's, its 28K, and at 5, its 32K :O. Which means, I was in the limits of my scanners, and they can even do 16K @ 30 degree's. I have calculated for 8 degree's, at 2.5M, the image will have to be about 35cm big. This time I will tune to that, since such a big scan angle isnt really necessary unless im at home ...

  9. #9
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    Cool

    Things;

    While the scanners can probably scan *some* images at 21 degrees when running at 20Kpps, they most certainly can *not* scan the ILDA test pattern at that wide of an angle.

    I've reviewed the ScanPro20's, and they're good scanners for the money. But that 20Kpps rating means that they can scan the ILDA test pattern at 20Kpps with at least an 8 degree scan angle. (8 degrees is the standard for the ILDA test pattern.) Some scanners can do it a little wider, some not. But you *never* want to try to tune them when you're scanning wide. You'll end up with garbage. And even with properly tuned scanners, if you try to scan the ILDA test pattern at 21 degrees, it will look terrible.

    Normally I tune at around 5 degrees, no matter which scanners I'm running. You don't want to be right on the ragged edge of the scanner's performance curve when you tune. That's why my scanner tutorial recommends that you increase the size until the circle stops expanding, and then back it off a couple degrees from there. You need the pattern to be large enough to see the details, but not so large that you're pushing the scanners too hard.

    Once you've got them tuned, you can test the max scan angle if you want. You should be able to get 8 degrees out of them with the ILDA test pattern running. If you're lucky, you might get 9 or 10 degrees before the circle starts to pull apart and shrink away from the center square. But 20 degrees is completely out of the question for the ILDA test pattern.

    Also remember that some other graphics files (and many abstracts as well) can be just as hard on the scanners as the ILDA test pattern is. So it may be that even with perfectly tuned galvos, you still have *some* files that you can't display at a wide scan angle of 20 degrees or more. Some files are just to complex to be displayed that wide. (You can solve the problem by either avoiding those files, or reducing your scan angle slightly - to say 15 degrees - while displaying those particular files.)

    Adam

  10. #10
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    Default

    Hey buffo, thanks for the detailed response. If I project a few letters, of times new roman font, it actually looks BETTeR bigger. When its smaller, it kinda looks like stuff is squished up and out of place. I will try some more tuning abit later

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