Amplifier Glow

Discussion in 'STX and STXL Series Cameras' started by Adam Block, May 12, 2015.

  1. Adam Block

    Adam Block Cyanogen Customer

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    Hi,

    It used to be the amplifier glow of the STX 16803 chip I used was variable... and was minimized in the course of processing the data (rejection). However, it has been steady on now for at least a year. Although it is only a small fraction of the chip... it is still somewhat annoying.

    Is there an adjustment I can make to minimize the glow?

    Thanks in advance,
    Adam
     
  2. Sreilly

    Sreilly Cyanogen Customer

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    Is there or has there been any issues with amp glow in the STX16803 cameras? Every image I have with this camera shows a light area in the upper left corner and I'm not aware of any reason for this.
     
  3. Doug

    Doug Staff Member

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    Not that I am aware of. Please upload a raw FITS frame - cooled dark frame would be best.
     
  4. Sreilly

    Sreilly Cyanogen Customer

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    Doug,

    Hope this helps. The file is zipped.

    Thanks,

    Steve
     

    Attached Files:

  5. Doug

    Doug Staff Member

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    That is not amp glow. These cameras show a slight baseline offset on the left and right edges of the image. It subtracts out in calibration and there is no additional noise associated with it.
     
  6. Sreilly

    Sreilly Cyanogen Customer

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    Thanks Doug. It must be my calibration routine because after calibration it's still there. I'll have to dive a bit deeper.

    Thanks,

    Steve
     
  7. Kevin Morefield

    Kevin Morefield Standard User

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    Doug,

    I have exactly the same thing on my 16803 STX (and my STT 8300) . It does not go away with calibration. If I have a fairly bright background it will be hidden but Blue in particular and low level backgrounds are a real problem. I provided a couple off examples to Tim. I use TheSkyX for camera capture rather than Maxim.

    Any advice would be appreciated.

    Thanks,

    Kevin
     
  8. Kevin Morefield

    Kevin Morefield Standard User

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    Was there any resolution for this?

    Kevin
     
  9. Doug

    Doug Staff Member

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    Please provide FITS images and your camera serial number(s).
     
  10. Tim Puckett

    Tim Puckett Guest

    Kevin, I looked at the pictures you shared with me.
    I will share them with Doug so he can look at them.
     
  11. Doug

    Doug Staff Member

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    Copying over messages sent by private message:

     
  12. Doug

    Doug Staff Member

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    Can you provide an uncalibrated raw frame, and a suitable dark frame, which illustrate the issue?
     
  13. Kevin Morefield

    Kevin Morefield Standard User

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    Here is a link to some examples from both my STX and STT. The STX examples are uncalibrated. I provided both before and after calibration examples on the STT.

    Doug, I'll provide a light and dark sample in a separate post shortly.

    https://www.dropbox.com/sh/ui1j9osrzabvvj6/AADfdnMdX6qtnQ7XDnMwYTSIa?dl=0
     
  14. Kevin Morefield

    Kevin Morefield Standard User

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    OK I've added one light and the corresponding Master Dark, Bias, and Flat Files. I also included a single raw dark frame.
    https://www.dropbox.com/sh/tqwi57pxzqox913/AABQ-9ysFrQ27EqBuALFUKrea?dl=0

    Looking at the individual raw dark frames, I saw the same sort of variation. That is, some frames had more or less of the upper left corner brightness. In this set of 20 darks, one in particular was worse than the others but those pixels would be ignored due to the integration process. Here are all 20 raw darks:
    https://www.dropbox.com/sh/cbh69oopab8hk4d/AACp5CriUzlcCZPMMK_iuWOta?dl=0

    Thanks,

    Kevin
     
  15. Kevin Morefield

    Kevin Morefield Standard User

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    Any further thoughts on this Doug?
     
  16. Doug

    Doug Staff Member

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    Thanks for the bump, I wasn't in the office very long on Friday.

    So there appears to be one image out of 20 that has some amount of amp glow. The most likely thing I can think of is a delay between the time the exposure completes and the download is initiated. The software is involved here; it triggers the start of download.

    Was the autoguider running while you were collecting those darks? That might be the cause of a delay, if the guide camera happens to read out at just the wrong time. MaxIm DL aborts the guider at the end of the exposure, to prevent this from happening.

    I notice that you are using TheSkyX for imaging. Can you do an equivalent series of darks using, say, CCDOPS? That will help narrow things down.
     
  17. Kevin Morefield

    Kevin Morefield Standard User

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    Doug,

    I took a single 20 minute dark frame with CCDops - I was going to try and figure out how to do a series but the first frame showed the glow so I stopped. I added it to this folder:
    https://www.dropbox.com/sh/ui1j9osrzabvvj6/AADfdnMdX6qtnQ7XDnMwYTSIa?dl=0

    Regarding the autoguider running while taking darks - no, I can't think of any reason the guider would be operating. I use CCDAutopilot for calibration frames and usually shoot in the day.

    The exposure delay in CCDops came up defaulted to zero and I left it there.

    Thanks,

    Kevin
     
  18. Kevin Morefield

    Kevin Morefield Standard User

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    Doug,

    One more thing - I was going to try imaging with the STX and STX guider using Maxim tonight to see if that eliminated the glow from the lights. But I could not figure out what combination of settings would get Maxim to take a photo using the external, STX guider. I kept getting images from the main camera when I tried exposing on the guider tab. Mind you, I am completely new to Maxim but I couldn't locate any discussion of the settings for STX/STX guider. If you can provide the key things I should set we can try this avenue for additional testing.

    Thanks,

    Kevin
     
  19. Doug

    Doug Staff Member

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    You have to turn on Dual Chip on the Setup tab, and also under the Setup for the driver itself, select the external guide head.
     

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