Resolved STF-8300M horizontal banding issue

Discussion in 'STF Series CCD Cameras' started by Steven Fong, Jul 20, 2021.

  1. Steven Fong

    Steven Fong Standard User

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    I bought this STF-8300M camera last year from adoroma.com to start serious AP imaging. It's brand new, works fine.

    But for the last few imaging sessions, I have noticed some horizontal banding on each frame at 100% crop. It looks like some sort of fixed pattern noise, but can't be removed by any dark or bias calibration. Actually the banding pattern looks more obvious on a calibrated & integrated master frame. It even show up in darks & biases to some degree.

    To sort up what's going on, I look back to the frames that were acquired last year when I just got this camera. They're clear, no such issues on them. I'm quite sure there's no much change to my imaging system, neither hardware nor software.

    I have searched around this forum and updated the drivers & firmware to the lastest version. The issue persists.

    Here are two pictures - one master light frame and one singal bias frame at 100% crop to show the issue:

    Banding.png

    Biasframe.png

    Please help with suggestions on how to resolve this issue.



    Steven Fong
     
    Last edited: Jul 20, 2021
  2. Colin Haig

    Colin Haig Staff Member

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    Hi Steven, what's the serial number of the camera?
    Are you using the original power supply that came with the camera, or something else?
    Are you using any USB hubs or extenders?
    I think it may need to go to our service expert @Bill
     
  3. Peter Bresler

    Peter Bresler Standard User

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    I had problems like that with a SX camera....it was due to the power supply. Be sure you have an adequate power supply.
     
  4. Steven Fong

    Steven Fong Standard User

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    Hi Colin,

    Thanks for your reply!

    Serial number is 83F190503

    When I am out under the stars I use a 50Ah 12V battery with a regulator. The battery is dedicated for the camera only. I do use a USB hub because the USB ports on my laptop is limited, but this system keeps unchanged since I start imaging last year.

    I take a bias and dark frame using the original power supply today at home. The camera is connected to the laptop directly, no hubs no extenders. But this horizontal pattern still exsists on the frames.

    Here are the frames I take today:
     

    Attached Files:

  5. Steven Fong

    Steven Fong Standard User

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    Hi Peter,

    Thanks for your sharing!
     
  6. Colin Haig

    Colin Haig Staff Member

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    Do you mean you feed the camera 12VDC from this "regulator"?
    What make/model is this regulator?
    Or is this an inverter that makes 120VAC from 12VDC ?

    Thanks for the FITS images. It has a different pattern to it.

    I think the camera has to go in to @Bill for repair. Please contact him at BILL (at) SBIG (dot) COM
     
  7. Doug

    Doug Staff Member

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    Don't send it in yet.

    I think you need to take a close look at your power source. Your "regulator" is probably a switching regulator, and it probably is generating a lot of electrical hash.

    Plug the camera into the power brick that came with the camera, and run a bias frame. If it doesn't have the noise then your problem is the "regulator".

    Colin noted that the pattern looks different in the FITS frames you uploaded. That's because the interference frequency changed. Many switching regulators change their switch frequency when the source voltage changes (e.g. battery level) or the load changes (e.g. different cooler power level).

    At this point I think the problem is in your power source, not your camera.
     
  8. Steven Fong

    Steven Fong Standard User

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    I'm sorry I haven't made it clear. That "regulator" regulates any 8~20V DC input to 12V DC output.

    I did not use this regulator in my last imaging session. I fed the camera with a single 12VDC battery that night. I can still see this noise pattern on those frames, which makes me really upset.

    Here's one:
     

    Attached Files:

  9. Doug

    Doug Staff Member

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    It was a good idea to test it with clean power. Those DC-to-DC converters can generate substantial electrical noise.

    Last things to try:

    Turn off all other equipment. There's a possibility that a recently-added or defective device is creating a lot of electrical noise. Some dew heaters create a lot of electrical noise, as do some motor drive units. Basically turn everything else off.

    Isolate the camera from the telescope (no grounding through the instrument) and connect only the USB and power cable. The idea is to determine if there's some kind of ground loop.

    If an isolated camera with nothing else running still has a problem, then the camera may have to come in for service.
     
    Last edited: Jul 22, 2021
  10. Steven Fong

    Steven Fong Standard User

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    You are ABSOLUTELY right Doug!

    It's the POWER!

    I did some detailed test and find out the source.

    For easy wiring and balancing, I use a cable extender. It's just a 2 feet long cable with a male and female connector at each end. I leave it on my camera as part of my rig, and forget it! I totally agree with you that I should take a serious look into the power, so I tested the camera with all kinds of power source yesterday. But I failed to remember the extender at first. So whatever power source I test, the camera was powered throught that cable, and gave that strip like noise pattern to every frame. I was totally out of any clue until I focused on that piece of cable. I removed it to find in surprise that everyting goes right! It's hard to imagine that a lillte piece of cable will make that HUGE difference!

    PS: If my memories are correct ( but they always are not...;)), you were in China in Sept, 2019? You gave us a talk on AP & SBIG in Hangzhou. I'm one of your audience. :)

    Thank you again Doug, and Colin!
     
    Last edited: Jul 22, 2021
  11. Doug

    Doug Staff Member

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    Steven,

    Actually that was Alan Holmes who visited China in 2019. He's one of the original founders of SBIG.

    Glad to hear you got it sorted.

    Doug
     

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