Resolved STXL 16200 and STXL FW8G

Discussion in 'Filter Wheels' started by Martin Pugh, Mar 21, 2017.

  1. w4sm

    w4sm Cyanogen Customer

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    I can't at the moment because, as mentioned above, my imaging camera has gone back to Bill Lynch for unrelated repairs. Prior to that, though, my problem was just as Martin Pugh described above. I realize that with a long focal length scope (16" f8 R-C), getting a star in the off axis guider (I have an FW8G-STXL) can be problematic until the guider is properly aligned with a good FOVi in The Sky X or similar program that lets you rotate your camera to put what should be a good star on the guider. I had my FOV PA calibrated using ACP, but still had major issues getting a star to be visualized in the guide imager. The camera seemed very insensitive. In dealing with this, I came upon this thread and used CCDOPS to check the offset setting on my guide imager. I used the technique Martin outlined above. My guide imager offset was set at "255." The default setting in CCDOPS was "0." There was not way that I could see to set anything other than the default, and so I did. Initial checking with my flat screen suggested that this HAD improved sensitivity, but before I could try it on a star field, the shutter issue developed, so I'm "on hold" until I get my 16200 back.

    So my questions are:

    1. Was "255" the wrong setting for my guide imager offset? ie. did the off axis imager come with the wrong setting?
    2. Is "o" the proper default setting?
    3. Is there any way in CCDOPS to change the setting to something other than the default?
    4. Does/should changing the offset from 255 to 0 improve sensitivity?


    Thanks,

    Stacey
     
  2. Doug

    Doug Staff Member

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    It's not an issue of sensitivity, it's a matter of whether the bottom end of your histogram is cut off at zero. It's about setting the zero point for the A/D converter.

    It sounds like your camera's offset was not set correctly, or the setting was lost somehow. Typically the value is somewhere in the middle, neither 0 or 255.

    I am following up with the team to try and find out where this problem originated.
     
  3. w4sm

    w4sm Cyanogen Customer

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    OK, please keep me posted. Seems like there should be a way to set a value between default "0" and "255."
    The default offset on the main imaging camera was "100."

    Thanks!
     
  4. Bill

    Bill SBIG Service and Repairs Staff Member

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    The Guider Offset for a 340 ccd is generally around 138, the Gain is around .50. I will enter these numbers into the camera and you should be fine.

    -Bill
     
  5. w4sm

    w4sm Cyanogen Customer

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    Thanks, Bill. The main imager may need resetting as well. I think I "defaulted" it when I was tweaking the guide imager.
     
  6. Bill

    Bill SBIG Service and Repairs Staff Member

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    I saw that. It will be reset.

    -Bill
     
  7. Doug

    Doug Staff Member

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    Just for the record... these settings are not intended to be accessed by end users. You don't have the test equipment and special software required to set it up properly.
     
  8. w4sm

    w4sm Cyanogen Customer

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    Hi Doug,
    I'm fine with that, BUT I would suggest if that's the case then CCDOPS should not have that option, instructions on how to make the change should not be posted on the forum, AND the camera should come with the proper offset initially.
     
  9. Doug

    Doug Staff Member

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    Totally agree, your camera did not have the correct offsets for the guider. We are investigating how that might have happened.

    Rarely it seems the values can somehow get corrupted. In those cases, as an alternative to sending the camera in for repairs, we may suggest trying adjusting these settings. In those cases we will recommend specific settings based on test data we have recorded for your individual camera.

    By default the feature is hidden in CCDOPS. We strongly advise against making any gain/offset adjustments without clear instructions to attempt it by our staff. It is unlikely you would be able to set it correctly without the data from our records.
     
  10. w4sm

    w4sm Cyanogen Customer

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    Got it. Thanks. Prior posts suggest that this may have happened to others as well.
    I'm just glad to have a solution. I know getting an off-axis guider calibrated on a long focal length scope can be difficult, but I was beginning to pull my hair out, what's left of it.
     
  11. RodG

    RodG Standard User

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    I have a problem very similar to what is described in this post.

    Upon taking an image with the Guider, I receive a file with all values =100 with the exception of a few hot pixels. No noise, just a flat signal. Using the instructions to view the guider offset in CCDOPS, I also have the settings of Offset=255 with Gain=0.45. Since the offset should be around 138 and not 0 or 155, is this something that could easily be changed to test whether this would fix this issue?
     
  12. Colin Haig

    Colin Haig Staff Member

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    Rod, would you mind giving us the serial number of your camera and filter wheel and/or remote guide head, when and where you bought it?
    Can you post a sample FITS image from the Guider here? Is it a FW8G-STXL or Remote Guide Head?
    Then we can dig into this for you.
    If you'd prefer, click Send a Private Message to get that info to me, and then we'll review and resolve here in the forum.
     
  13. RodG

    RodG Standard User

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    Here is the file.
     

    Attached Files:

  14. RodG

    RodG Standard User

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    I think we have the issue solved. I have been in direct contact will Bill and he was able to remote into my computer and change the Guider Offset and Gain. Now I am getting what appears to be a good image. See new file.
     

    Attached Files:

  15. Bill

    Bill SBIG Service and Repairs Staff Member

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    Rod and I connected via TeamViewer and I changed his offset and gain settings to 138 and .52. Test images looked "normal".

    -Bill
     
  16. Colin Haig

    Colin Haig Staff Member

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    Nice work Bill!
     
  17. RodG

    RodG Standard User

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    Agreed!
     

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