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ASI294MC Pro amp glow persists after dark frame calibration

ZWO ASI294MC Pro CMOS Amp Glow Deep Sky IC1848 IC Objects Nebula Troubleshooting
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Girish avatar
Girish avatar

Need some help with identifying the issue, first Yes I am aware the ASI294MC Pro has amp glow issue, so here is what I did.

  • 125 images, each image 5 minutes long gain was 125

  • Bais 100

  • Flat 30

  • Dark 30 frames

Processed all using Pixinsight and I still have amp glow, I am definitely sure I am missing something here and definitely not able to catch it.

I recently got ASI294MC Pro and before that I was using ASI533MC Pro, ASI533MM Pro, ASI071MC Pro and since they dont have Amp glow issue so never needed any help :( here you can see on right side those blue strikes, they were amp glows :(

📷 IC1848 copy.jpgIC1848 copy.jpg

andrea tasselli avatar
andrea tasselli avatar
Calibration can be tricky with NB filters as you need to exactly match the temperatures of darks with those of lights.
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Alejandro Moreschi avatar
Alejandro Moreschi avatar

Hello, I has this cam too. I recommend that you use gain 120 and as Andrea says, try to keep all the parameters consistent across all shots.

I now use in my ZWO 294 MM PRO and before in the ZWO 294 MC PRO this setings

Gain 120

Temp -10

Offset 8

I know that ampglow shouldn't appear in your image, but the background looks very bright to me, as if the background extraction wasn't done correctly and because it's so bright, the ampglow, which should be very subtle, is more noticeable.

I've seen in many videos that they recommend using “darkflats” with this camera and not using bias. And the flats absolutely have to be 2 seconds or longer to turn out well.

Arun H avatar
Arun H avatar
Alejandro Moreschi:
I've seen in many videos that they recommend using “darkflats” with this camera and not using bias. And the flats absolutely have to be 2 seconds or longer to turn out well.


4 seconds to be safe. The darks have to match the lights/flats exactly in gain and temperature. The idea behind 4s is that for smaller times, the driver uses on chip circuitry which can heat up the chip and cause inconsistencies. Using a time larger than 4 seconds allows the computer circuitry to be used, but you have to use a large enough exposure to avoid timing errors.
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AlexFilothodoros avatar
AlexFilothodoros avatar

Aren’t flat darks also needed for this sensor?

andrea tasselli avatar
andrea tasselli avatar
Yes, they are, but I never found any issue with shorter (less than 1s) or much shorter (less than 0.1s) flats with either the MM or MC variants.
Arun H avatar
Arun H avatar
Girish:
Need some help with identifying the issue, first Yes I am aware the ASI294MC Pro has amp glow issue, so here is what I did.

125 images, each image 5 minutes long gain was 125

Bais 100

Flat 30

Dark 30 frames


I just realized you used biases for calibration. With this camera, avoid the use of biases. Calibrate your flats with darks of the same time, gain, and temperature as the flats; calibrate the lights with darks of the same time and temperature and gain as the lights and with the calibrated flats.
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losman_2 avatar
losman_2 avatar

I agree with other recommendations. I’ve used the 294mc pro for years and I never use bias frames, just darks, flats, and darks flats. I do my flats before my dark flats so I know about what the timing of the dark flats need to be. I also only use gain = 120. I make sure my darks are at all the same settings, including the temperature but I don’t worry about that doing flats and dark flats. Hope that helps.

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Girish avatar
Girish avatar

Thank you everyone!!! finally I was able to get it working! i just posted my image on NGC-1893 and there I use ASI294MC Pro and setup was Dark, Dark-flats, and flats along with light and boooommm, no AMP glow of any sort!! Awesome!