Resolved STT3200 banding

Discussion in 'STT Series' started by mike m benjamin, Aug 26, 2020.

  1. mike m benjamin

    mike m benjamin Cyanogen Customer

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    I can't figure out what the banding is on the lower quarter of my subs, shows up much worse in narrow band (3nm), these were aquired using my Meade 12" F8, with the AO-8t, dithering enabled. the 005oiii is a single sub and the other is the stack.
     

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  2. Colin Haig

    Colin Haig Staff Member

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    I'm going to ask @Bill to take a quick look.
    I see one image with the obvious banding is in CCDOPS and the other is a bunch of processing was done in PixInsight.
     
  3. mike m benjamin

    mike m benjamin Cyanogen Customer

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    That's true, it's the combined raw stack of 34 subs.
     
  4. Doug

    Doug Staff Member

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    We need individual, unprocessed frames to be able to analyze camera behavior.

    If it needs a stack in order to see it, then we'll need to get the original images for that stack, including calibration frames.
     
  5. mike m benjamin

    mike m benjamin Cyanogen Customer

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    Sure Doug, I can supply plenty of raw unprocessed frames if needed.
     
  6. Doug

    Doug Staff Member

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    Yes please upload a few raw, completely unprocessed frames. And a few matching darks. We need to see the data exactly as it came out of the A/D converter.

    We really have no idea what PixInsight did to the pixels. It likes to rescale everything to 0-1 data range, which renders EGAIN meaningless, we can't tell where the bias and saturation levels are, etc. It's totally mangled from the perspective of diagnosing potential camera issues!
     
  7. mike m benjamin

    mike m benjamin Cyanogen Customer

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    Here you are doug.
     

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  8. Doug

    Doug Staff Member

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    I see it's a bit random. Some images don't show it. Others only show just a little at the very bottom. Others have it on a good chunk of the bottom of the image.

    To me, this looks like interference. I've seen something that looks a lot like this in a completely different camera model (not SBIG). The source of the noise turned out to be the USB interface. The camera would start downloading the frame into memory, and the data would be nice and clean. After a while enough data accumulated and the PC would start downloading, and that's when extra noise appeared on the frame. The pixels on the bottom are read last, which is why the noise is at the bottom. (We proved that was the cause by putting a software breakpoint in MaxIm DL and forcing the USB download to wait until after the chip finished reading out into the camera's frame buffer.) What you are seeing looks very similar!

    I'm not sure why you would see that on an STT camera - it's not something we've seen before. Is this something that just started happening? Do you have a ferrite on the USB cable? How is the camera powered - using the power brick and cable that came with the camera?
     
  9. mike m benjamin

    mike m benjamin Cyanogen Customer

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    I just bought the camera earlier in late spring, haven't used it much, I did check a few M57 Oiii subs from a month or two ago and I do see the pattern, not quite as pronounced but visible. Camera didn't come with a power supply. My CEM120 has through cable routing with one aux port. I wired it up a few years ago to power my STT8300 at the time, I still use it. It gets its power from a pyramid power supply. I didn't notice this issue with the 8300. No, I haven't used the ferrite on the usb cable, I will give it a try, it's just a single pass through the ferrite?
     
  10. mike m benjamin

    mike m benjamin Cyanogen Customer

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    Also, does the ferrite mount near the camera or the laptop, or does it matter?
     
  11. Doug

    Doug Staff Member

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    Best to put it close to the camera.
     
  12. Colin Haig

    Colin Haig Staff Member

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  13. mike m benjamin

    mike m benjamin Cyanogen Customer

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    Well, I figured out the problem. The camera firmware was 2.65, when did the 2.66 update come out? I did check the drivers/firmware when I picked it up 4-5 months ago. Maybe I didn't check it properly at the time. Anyway it's just fine now. Now I have a large dark library to redo, along with reshooting the bubble nebula,lol.
     
  14. Colin Haig

    Colin Haig Staff Member

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    Update came out in November 2019, to address pattern noise in the Bias frames. It will slow the download time slightly (like less than 0.5s).
     
  15. mike m benjamin

    mike m benjamin Cyanogen Customer

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    Well I can confirm it works!
     
  16. Colin Haig

    Colin Haig Staff Member

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    Glad to hear it was a simple fix.
    I encourage STT owners to install the latest firmware.
     

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