Artificial star for checking CCD orthogonality?

Discussion in 'CCDOPS and SBIG Universal Driver (Retired)' started by Chris Anderson, Nov 1, 2017.

  1. Chris Anderson

    Chris Anderson Cyanogen Customer

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    I am having an issue with my FSQ @f3.6, .73 reducer, and my STT8300. One corner of the field is soft. I am introducing a tip/tilt device (a camera plane adjuster made by Moonlight) into the fray. So far, it appears to be an issue with either the focal reducer, or maybe the CCD chip is ever-so-slightly off square? Can I use an artificial star to bench test the adjustments in, say, the basement? I know they are used for collimation, but it seems that the same premise could be used to check the corners of the CCD and make minute adjustments with the CPA. Thoughts?

    Chris
     
    Chris Anderson, Nov 1, 2017
    #1
  2. Colin Haig

    Colin Haig Staff Member

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    Depends on how long and skinny your basement is ;-)
    I'm just another customer, and I've tried the artificial star idea, bt found I could not reach good focus. I think you might need 50-250' of distance to make it work. You may have better luck.
     
    Colin Haig, Nov 1, 2017
    #2
  3. Doug

    Doug Staff Member

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    f/3.6 is extremely fast; in some cases you may have to shim to get things to work perfectly.

    It's hard to make a really good artificial star. I've read about various ways to do it, but when I've tried it I've never been terribly happy with the results.
     
    Doug, Nov 1, 2017
    #3
  4. Chris Anderson

    Chris Anderson Cyanogen Customer

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    I ordered a "star" from OPT. Cheap. With the camera plane adjuster, I should not need to shim, as that's what it does. Colin, I have a Silence of the Lambs basement, so I may have to set up said AS outside. Should be interesting!

    Quote:
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    Adjustment is made at 3 points 120 degrees apart. Each location has a pair of stainless-steel push and pull adjusters. Use a smaller Allen wrench or small pin to turn the adjusters.

    The rear focuser side stainless-steel adjuster is the pull side and the front camera side stainless-steel adjuster is the push side. Be sure that they are both moved in unison and left in a tight/snug position. About .020” of tilt/tip can be made with the Sidewinder.
     
    Chris Anderson, Nov 1, 2017
    #4

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