STT-8300 - Possible Amp Glow Problem

Discussion in 'STT Series' started by Dean J., Feb 10, 2016.

  1. Dean J.

    Dean J. Standard User

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    Vista, CA
    Hi All, I'm trying to track down the cause of a defect that intermittently appears in the upper left corner of my new [2 months old] STT-8300. I have had the camera out imaging twice and both times I see a "glow" in the upper left corner of some of my images. The defect occurs in about 10% to 15% of my images. Although it is most noticeable in the clear and red filtered images, I also see hints of it in the green and blue filtered images.

    My usual exposure time is 360 seconds.

    The interesting thing is that I don't see the defect in my 360 second dark frames but the defect does show up in mt 2 second dark frames [used in calibrating my flat field frames]. The first 2 second dark frame does not show the defect but subsequent 2 second darks do appear to contain a small amount of the effect.

    The defect will occur when the "Vdd Normally Off" setting is checked and when it is unchecked.

    Hopefully someone here can advise as to a solution. I hate to throw away 10 to 15% of my subexposures.

    I checked the camera's drivers - they are up to date. One of the two firmware files - sttga.bf2 is version 2.58. I notice that there is a newer file but I haven't updated that firmware file yet.

    I have uploaded two reduced size image files - glow.jpg and no_glow.jpg - which shows the defect. View attachment 1401 View attachment 1402 View attachment 1401 View attachment 1402 View attachment 1401 View attachment 1402

    Thanks in advance for the help.

    Dean J.
    glow.jpg no_glow.jpg
     
  2. Dean J.

    Dean J. Standard User

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    Here is another exemplar of the defect. This was a red filtered image. The second image was taken immediately after and shows no evidence of the defect.

    Dean J.

    glow2.jpg no_glow2.jpg
     
  3. Adam Robichaud

    Adam Robichaud Staff Member

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    We're investigating this now. Stay tuned.
     
  4. Dean J.

    Dean J. Standard User

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    Thanks Adam, I appreciate your help.

    I can send you the original FITS files of the images I posted above if you need them.

    The surrounding white background sort of mutes the effect on the images above. However the "glow" or whatever it is is quite pronounced.

    I am also using the FW8G-STT filter wheel with the camera. Perhaps that might explain why I don't see the effect in the dark frames but I do see the "glow" in the light frames.

    Dean J.
     
  5. Dean J.

    Dean J. Standard User

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    I am re-posting the images with the "amp glow", or whatever it is. The black border makes the defect show up a lot better.

    I just re-checked the two sets of dark frames I have taken since I have had this camera and I don't see the defect at all. I have been seeing the defect with my light frames about 10% to 15% of the time but it hasn't been present in the dark frames.

    The only thing I do differently with the dark frames is that I don't bother to connect the filter wheel guider camera to the main camera. I do dark frames at home in a dark room. I do connect the filter wheel to the camera though.

    glow3.jpg glow4.jpg
     
  6. Dean J.

    Dean J. Standard User

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    Well, it looks like the issue has been resolved and it is not amp glow. I had sent in the camera to Bill Lynch at SBIG Repair to clean the CCD chamber as discussed in another recent post. I sent along a USB stick with raw images showing the "glow" and asked Bill if he would take a look at the images while the camera was there.

    Bill was apparently able to reproduce the effect and tracked the issue down to a reflection from the CCD light shield... which he corrected.

    I am very pleased with the quality of service that I received from Bill. He is a really nice guy and a pleasure to deal with. If you ever have a problem with your SBIG camera and need repairs performed - and I hope that you don't - you can rest assured that you will get first rate service from Bill. He certainly is a credit to the Diffraction Limited/SBIG organization.

    Regards,

    Dean J.

    Edit: 4/3/2016 - After the first use of the camera after getting it back from SBIG repair for cleaning of the CCD chamber I am still getting the "amp glow" defect in the upper corner of my images. It is quite pronounced and is appearing about 25 - 30% of the time now at varying degrees of intensity.
     
    Last edited: Apr 4, 2016
  7. Geoff Stone

    Geoff Stone Cyanogen Customer

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    Interesting - I've been seeing the same thing on my camera. It seems to come and go so I've never tracked it down. I'll have to ask Bill about it and how to fix it.
     
    Last edited: Mar 21, 2016

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