White dotted lines in STXL-16200

Discussion in 'STX and STXL Series Cameras' started by EricC, Feb 13, 2017.

  1. EricC

    EricC Cyanogen Customer

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    While processing shots from my new STXL-16200 with CW8-STXL filter wheel, I noticed some white, dotted, horizontal lines in the top ~ 1/3 of many of the frames. These lines appear in many (but not all) frames using different filters, so they are unlikely due to reflections.

    Does this indicate something is wrong with the camera?

    It may be a coincidence, but the flats have darker bands in the upper ~ 1/3 of the frame.
    More information is at http://eccssw.com/astro/Horizontal_dotted_lines/index.htm, including a link to the .fit file and a picture showing the lines are in different locations in each Light frame.
    M96-0007_Ha,partial.JPG
     
  2. Colin Haig

    Colin Haig Staff Member

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    Hi Eric,
    How's your camera powered? e.g. are you using the original SBIG power supply plugged into 120V AC and connected directly to the camera ? Or are you running through a mount, running off DC, a power pack or inverter? It looks a little bit like it might be RFI/EMI.
    How's the camera connected to the PC? USB2.0 direct cable with ferrites on either end?
    Do you see these on the darks / bias frames as well?
     
  3. Doug

    Doug Staff Member

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    I agree with Colin, that looks like electrical interference. Probably caused by bad power or some strong noise source nearby.
     
  4. EricC

    EricC Cyanogen Customer

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    I have a 15 volt, 9 amp continuous, 12 amp surge AC/DC converter from Astro-Physics that powers all the gear.
    The camera and focuser are connected to a USB 2.0 powered hub, which is then connected directly to the PC. All cables go through the mount.

    I don't the lines in any of the Dark or Bias frames, which were taken indoors using the 120v AC adapter that came with the camera. The indoor shots also only had the camera running - no mount, USB hub, focuser, or dew heater.

    Assuming the white lines are from electrical interference, what's the best way to determine the culprit?
    What are the most likely culprits? I'm in an RV park so don't think there are any strong noises nearby.
    Should I try adding more ferrites, and if so, on which cables and which end? How far from an end?

    Any idea why the lines would only be in the top ~ 1/3 of the frame?
     
  5. Doug

    Doug Staff Member

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    Your evidence indicates that the noise is coming from the Astro-Physics power supply (or perhaps more likely from the mount itself, feeding back into the power).

    I strongly recommend using the power brick that came with the camera.
     
  6. Colin Haig

    Colin Haig Staff Member

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    This could account for some of the vertical column variations and horizontal banding I'm seeing in the flats (in the other thread).
     
  7. EricC

    EricC Cyanogen Customer

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    I don't see any lines in the pictures I took today. Since the time I got the lines a week ago, I rearranged the cables on the camera, but did not change anything else. So I'll cross my fingers that the problem is gone, and will check in the future.
    Thanks for your help.
     

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