Light leak in FW8S-STXL filter wheel

Discussion in 'STX and STXL Series Cameras' started by Tom Bash, Oct 16, 2020.

  1. Colin Haig

    Colin Haig Staff Member

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    Tom, if you want to send it in, please contact @Bill for service. Bill (at) SBIG (dot) com.

    Please send FITS files, raw, unprocessed, binned 1x1, no dark or bias subractions, shot through a clear slot (no filters).
    We'd want bias, dark, light frame. The dark should be the same length as the light.
    Have you double-checked that your filters are in the correct orientation (shiny side toward the telescope) ?
     
  2. Tom Bash

    Tom Bash Standard User

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    Hi Colin,

    I checked my filters, that was one of the first things I considered when we started going down the IR preflash LED route. They are installed correctly.
    I uploaded the files you requested, and I connected with Bill. I will be shipping him my camera only tomorrow.
    The light frame was taken with the filter wheel capped in a dimly lit room through an empty filter slot.

    Regards,
    Tom
     

    Attached Files:

  3. Colin Haig

    Colin Haig Staff Member

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    Ok this light frame is showing what looks like CCD polishing marks.
    Going to ask @Doug to comment.
     
  4. Doug

    Doug Staff Member

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    Yes, they are CCD wafer polishing marks. RBI Mitigation appears to be turned on for the light frame, but not the dark or bias frame.

    And, in fact, the FITS header agrees - RBI Pre-flash is turned on for the light frame:

    READOUTM = 'Raw w/RBI pre-flash' /Readout mode of image

    However, the FITS header for the dark frame does not have RBI turned on:

    READOUTM = 'Raw ' / Readout mode of image

    So there's your problem. Either use RBI mitigation, or do not. You can't mix and match. The light frames and the calibration frames must be taken in the same mode!

    Unless you are experiencing RBI issues (i.e. afterimages from bright stars on subsequent frames) it is much better to run with it turned off.
     
  5. Tom Bash

    Tom Bash Standard User

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    Hello,

    I got my camera back from Bill, he was not able to find anything wrong with it, but recently I had some time to work with it and it appears the pre-flash LEDs are an issue. I used MaxImDL 6.26 for all image acquisition, only using RAW mode. I have uploaded dark frames from two different nights, on each night are 3 sequential dark frames that were taken with Autosave, and the first in each series shows the same wafer polishing marks that show up when RBI pre-flash mode is used. The following 2 darks in each sequence show the pattern at reduced intensity. All darks were taken with the telescope capped and after sunset. The pre-flash LEDs must be turning on intermittently when they shouldn't, which may be why Bill didn't find anything wrong, but clearly there is a problem here.
     

    Attached Files:

  6. Doug

    Doug Staff Member

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    Make sure the camera firmware is up-to-date.

    Make sure the SBIG Universal drivers are up-to-date.

    You can do both things using the SBIG Driver Checker. Get the latest version from our web site.
     
  7. Tom Bash

    Tom Bash Standard User

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    Everything was/is up to date, I saved screen captures into the attached word document that shows the driver and firmware versions. I had updated them a few months ago based on your suggestion while debugging this problem.
     

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  8. Doug

    Doug Staff Member

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    @Colin Haig why don't you organize a Teamviewer session with him, to make absolutely sure there isn't some kind of software configuration error going on here?

    Failing that, it would have to be an issue with the IR Preflash LEDs. I recall one occasion in another camera where they got "stuck on" partway due to a hardware fault... maybe something like that is going on here? I don't know if @Bill would had considered that as a possibility, because it's extremely rare.
     
  9. Tom Bash

    Tom Bash Standard User

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    I decided to look at each of my dark frames from when I first was able to use this camera, and the RBI pre-flash pattern is visible to some extant in about 20% of my darks, in every dark sequence I took. I never looked at them before because I assumed, well, they are darks, and after acquiring them I would create masters. For what it's worth, the pattern usually but not always is the strongest in the first dark taken in a series, and it fades over the next 2 or 3 darks in sequence. The rest of the darks in the sequence have no visible pattern.

    I have uploaded 2 of those darks, one acquired by CCDSoft and another in MaximDL 6, both reading out in raw mode. All my darks were read out in raw mode. So whatever is causing this is intermittently affecting darks and causing the light to appear in my lights.
     

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  10. Tom Bash

    Tom Bash Standard User

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    I'm open for a Teamviewer session, just let me know if I need to have the camera setup and connected. But consider that this issue is consistent across two different laptops running two different operating systems (Xp and Win10), using three different camera control programs (CCDSoft V5, MaxIm DL 5 Pro, MaxImDL 6 Pro), and before and after updating drivers and firmware. So it seem unlikely to me it is a software issue.
     
  11. Colin Haig

    Colin Haig Staff Member

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    Hi Tom,
    Are you available to do this today? If not, suggest 2 other times.
    Let me know when you can be available. If it has to be after normal work hours, I can probably do that.
    I'm on EST (UTC-5).

    If so, here's what we should start with:
    Windows 10 PC
    Install Teamviewer if you have not already done so.
    Camera powered up and connected.

    When you launch TeamViewer, it will show an ID and password. Send that to me using the Send a Private Message link under my photo at left.
    Thanks.
    Colin
     
  12. Tom Bash

    Tom Bash Standard User

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    I have Teamviewer on my Win10 PC, and can be available at 4pm your time (1 pm my time). If that doesn't work anytime tomorrow after 12:30 your time will work for me.
     
  13. Colin Haig

    Colin Haig Staff Member

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    Ok, let's connect at 4pm / 1pm.
     
  14. Colin Haig

    Colin Haig Staff Member

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    Long session, not completely resolved.
    We've eliminated the following possibilities: light leak, driver versions, firmware.
    Next step is I will review logs and images.
    There is a residual image effect happening on the first few darks; I need to determine the cause.
    Windows 10 USB selective suspend issue may be at play on the one test machine. Changes some of those settings.
    The other PC was not tested.
     
  15. Tom Bash

    Tom Bash Standard User

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    Thanks again for all your time this afternoon. If there is value in looking at the logs and images on my Xp notebook let me know and you can TeamViewer into it. It has MaxIm DL 5 pro on it.
     
  16. Doug

    Doug Staff Member

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    MaxIm DL V5 is not compatible with the Preflash function of modern SBIG cameras.
     
  17. Tom Bash

    Tom Bash Standard User

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    Hi Colin,

    Have you found anything yet?
     
  18. Tom Bash

    Tom Bash Standard User

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    Hello,

    It's been a couple of weeks now, can you please let me know if your found anything in your investigation of the camera files?
     
  19. Colin Haig

    Colin Haig Staff Member

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    Tom, we've reviewed the camera files, logs, the service visit the camera made, and have the following comments:

    1. MaxIm DL 5 will not work with your STXL camera.
    It is many years out of date, and predates the STXL-6303 camera.
    If you insist on trying to use the XP laptop with MaxIm 5.xx we know for a fact that will NOT work properly with the STXL camera.
    It will likely end up turning on the Residual Bulk Image Pre-Flash LEDs, which will flood the chamber with IR (Infrared) light.
    This is the probable cause of many of your troubles.

    2. MaxIm DL 6 crashing on Windows XP laptop in the field
    MaxIm DL 6 is not supported on Windows XP.

    Windows XP is not supported by Microsoft, ASCOM, or Diffraction Limited.
    Likely it's time to move on from XP and get a new laptop.

    If you want to try to get it to go, here's what I've found out:
    Windows XP Version 2002 Service Pack 3 with all updates, including .NET framework must be installed.
    MaxIm DL Pro 6.26, ASCOM Platform 6.4 SP1, and SBIG Driver Checker 4.05.
    See this article:
    https://ascom-standards.org/FAQs/Plat6OnXP.htm
    MaxIm will crash as some drivers included with it will not work on XP.
    Rename C:\Program Files\Diffraction Limited\MaxIm DL 6\CCDPlugDLImaging.dll to CCDPlugDLImaging.dll.bak
    This will disable the DL Imaging driver which is not compatible with XP.

    We can't guarantee results; we don't support it; and its a wonder if it works.
    It did for me on a test XP machine with an older SBIG camera.
    Again, not supported.
    3. Camera warranty visit - no fault was found during Bill's tests of the camera. Nothing needed to be replaced, working as specified when it left the factory and when it got to Bill.

    4. RBI - don't use it.

    5. Saturation during sky flats - cut back on your flat field exposure length.
    This sensor is non-Antiblooming, as it is intended for photometry - its behaviour is different from other cameras you may have experience with.
    It has a 100,000 electron full well depth, and you should probably keep the ADU count below 40,000 for the flats.

    6. The order you do things may be influencing what is going on.
    The camera should be powered up, allowed to stabilize for 10 minutes, then put the cooler on, and allow it's temperature to stabilize.
    If you're doing photometry, then you may wish to stabilize it for 30 minutes.
    Try changing the order of your sequences - focus the camera/telescope setup, then switch to your image run.
    Build a Master Dark library.
    Toss out any bad darks.

    That's all I've got for suggestions at this point.
     
  20. Tom Bash

    Tom Bash Standard User

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    Thanks for getting back to me Colin. I will be using the Win10 notebook you accessed via TeamViewer to control my STXL camera from now on, and save my Xp notebook for controlling my STL camera, I never had an issue with that.

    FYI the other cameras I have experience with are the STL-1301 and ST-9E, both are also non-antiblooming, and my understanding is you can take flats to fairly high ADU count with non-antiblooming cameras because the response is linear. That's what I have always done with my other cameras and the flats did their job with no issues.

    I will experiment with my sequence of images to see if I can prevent the RBI artifacts from occurring. I will take flats with lower ADU count, < 40,000, and see if follow up darks have the RBI artifacts.
     

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