Amp Glow with ASI183MM in PI Using Calibration Frames

[dugstruble]

To begin with, I have read through several threads on several different forums and cannot find a good fix for excessive amp glow using the ZWO ASI183MM and WBPP in PI.

That being said I have tried optimizing dark frames and not using bias, which some have recommended.

I normally capture small PNs that I can crop out the amp glow. I am working on a full frame nebula now. The Ha and OIII has enough signal where the master does not show amp glow, but SII is usually always weaker with signal and as such, always shows amp glow for me.

There needs to be some things that initially need to be scratched off the list of possible problems. All my calibration frames are done correctly; darks are at the same timing, temp, gain and offset. The bias are at zero timing with the same gain and offset. Flats are done correctly as well.

DBE doesn't really do a perfect job on my amp glow.

Even if there is a post process in PI, I would be fine with that, but don't know of any to remove amp glow.

If anyone has any personal experience with the ZWO ASI1833MM and PI and figured it out, I would love to hear that.

Thanks,
Douglas J Struble

Douglas J Struble's gallery

Astrophotography by Douglas J Struble on AstroBin

www.astrobin.com

 

[pfile]

post your raw frames so someone can take a look. one thing is for sure - dark scaling/optimization just won't work, so that's a dead end.

 

[dugstruble]

post your raw frames so someone can take a look. one thing is for sure - dark scaling/optimization just won't work, so that's a dead end.

Just the raw fits subs? How many would you like? I do short 2 min subs given my bortel 8 skies. I have around 250 subs in SII. I can upload whatever to my drop box account and post a link to download.

Thanks,
Douglas

 

[pfile]

Just the raw fits subs? How many would you like? I do short 2 min subs given my bortel 8 skies. I have around 250 subs in SII. I can upload whatever to my drop box account and post a link to download.

Thanks,
Douglas

probably 10 darks would be enough, and 10 flats (and matching darks for those, or bias frames) and then a couple of lights.

 

[stephan]

Hi Douglas,

I'm using the 183MMPro without any calibration issues. The lights show excessive amp glow of course, but they just calibrate fine. I attach a screenshot where you see the original light with amp glow in the background and the calibrated (using darks/flats/bias and WBPP default settings) without any visible amp glow in the front. I was using Gain 56, T:-10C, 240sec in that shot just with a luminance filter.

As already mentioned in another answer dark optimization does not help against amp glow. Do not activate it for this camera but make sure the darks are taken at the very same temp/gain/offset as the lights.
The hint you got from your friends to use NINA for processing does not make any sense as NINA is only for capturing.

I see in your astrobin that you are shooting with different gain settings. Are you absolutely sure that only the proper darks and lights (those with the same gain!) are combined? You might check this in the calibration tab of WBPP by clicking on any entry in the light table at the bottom of the window and then click the "Show Calibration Diagram" button.

It is also mandatory to create all(!) frames (light/dark/flat/bias) with the same capturing software. May be you created your dark frames are while ago with a different software?

Regards,
Stephan

 

[fredvanner]

I also occasionally use an ASI183MM. The use of precisely matched darks (exposure and temperature) has always corrected the amp glow for me.
I don't think you can achieve the required accurate match using dark optimisation - you need the matched darks.

[And yes, I did have some tracking issues on that day ]

 

[dugstruble]

probably 10 darks would be enough, and 10 flats (and matching darks for those, or bias frames) and then a couple of lights.

I just realized I don't have the individual dark files; just a master dark. I think I perhaps need to take new darks. Someone in this thread said the darks need to be taken with the same software. It is possible I took them with a different program I was using just for calibration frames over a year ago.

 

[fredvanner]

Particularly for cameras with strong amp glow, it is advisable to update the darks frequently (the infrared emissions of the read-out amplifier are less stable than the sensor dark current).
With my ASI183MM (uncooled) I took darks every night.

 

[dugstruble]

Particularly for cameras with strong amp glow, it is advisable to update the darks frequently (the infrared emissions of the read-out amplifier are less stable than the sensor dark current).
With my ASI183MM (uncooled) I took darks every night.

Thanks.

 

[dugstruble]

Unfortunately making new darks did not help. I used the same software I capture with too, SGP. Bummer.

 

[cloudbait]

Unfortunately making new darks did not help. I used the same software I capture with too, SGP. Bummer.

I don't think you've posted examples of your raw darks and raw lights (one or more of each). That's what we need to see.

 

[dugstruble]

I don't think you've posted examples of your raw darks and raw lights (one or more of each). That's what we need to see.

Thanks. Here is a drop link to a zipped file containing 10 lights, 10 darks, 10 flats and a master bias. For bias, all I have is the master:

Sh2-284 Raw Lights & Darks.zip

Shared with Dropbox

www.dropbox.com

 

[fotojojo]

Sorry to hear you are having trouble. It is my understanding that for an uncooled camera, your darks must match your lights in both exposure and temperature to be effective calibration frames. Can you confirm if your darks were taken under the exact (or near to) same conditions as your lights?

 

[dugstruble]

Sorry to hear you are having trouble. It is my understanding that for an uncooled camera, your darks must match your lights in both exposure and temperature to be effective calibration frames. Can you confirm if your darks were taken under the exact (or near to) same conditions as your lights?

It is cooled. ASI183MM Cooled. Never the less, my darks and lights are both at 120s, -20C, 200 gain and -33 offset.

 

[cloudbait]

Thanks. Here is a drop link to a zipped file containing 10 lights, 10 darks, 10 flats and a master bias. For bias, all I have is the master:

Sh2-284 Raw Lights & Darks.zip

Shared with Dropbox

www.dropbox.com

I ran all your files through WBPP, default settings except for auto pedestal (which didn't actually make much difference, but there were some zeros in the master without it). The focal length or pixel size is apparently wrong in the headers, so the pixel scale was wrong and didn't let Solver work, but I manually entered 0.7"/pixel and it solved fine. No sign of amp glow (or gradients) in the output as all. Looks great to me.

UPDATE: Looking at your raw lights, the header lacks your camera pixel size of 2.4μm. You should make sure that SGP is configured to include that key.

 

[dugstruble]

I ran all your files through WBPP, default settings except for auto pedestal (which didn't actually make much difference, but there were some zeros in the master without it). The focal length or pixel size is apparently wrong in the headers, so the pixel scale was wrong and didn't let Solver work, but I manually entered 0.7"/pixel and it solved fine. No sign of amp glow (or gradients) in the output as all. Looks great to me.

UPDATE: Looking at your raw lights, the header lacks your camera pixel size of 2.4μm. You should make sure that SGP is configured to include that key.

View attachment 22546

Wow that looks great! I'll look into your recommendations. Thanks!

 

[dugstruble]

I ran all your files through WBPP, default settings except for auto pedestal (which didn't actually make much difference, but there were some zeros in the master without it). The focal length or pixel size is apparently wrong in the headers, so the pixel scale was wrong and didn't let Solver work, but I manually entered 0.7"/pixel and it solved fine. No sign of amp glow (or gradients) in the output as all. Looks great to me.

UPDATE: Looking at your raw lights, the header lacks your camera pixel size of 2.4μm. You should make sure that SGP is configured to include that key.

I don't see a key for the camera pixel size. See attached image. I am using the last version of SGP before they switched to a subscription based model, as I have not had any other issues. Where do you manually enter in the pixel scale of 0.7"/pixel in WBPP in PI? In the meantime, I just manually fixed it. Didn't turn out too bad.

 

[cloudbait]

I don't see a key for the camera pixel size. See attached image. I am using the last version of SGP before they switched to a subscription based model, as I have not had any other issues. Where do you manually enter in the pixel scale of 0.7"/pixel in WBPP in PI? In the meantime, I just manually fixed it. Didn't turn out too bad.

I've never used SGP. But that list you provided looks like a mechanism for adding things to the filename of images, not to the FITS header. I've never seen image acquisition software that didn't include the camera information if it was provided in the options/settings. There really should be a place in SGP where you can define your equipment, including camera pixel size.

If ImageSolver fails during WBPP because its seed values (position, focal length, pixel scale, pixel size) aren't correct, it will stop the processing of the script and open the ImageSolver dialog. There you can fill in the correct values manually and then WBPP will continue.

 

[dugstruble]

I've never used SGP. But that list you provided looks like a mechanism for adding things to the filename of images, not to the FITS header. I've never seen image acquisition software that didn't include the camera information if it was provided in the options/settings. There really should be a place in SGP where you can define your equipment, including camera pixel size.

If ImageSolver fails during WBPP because its seed values (position, focal length, pixel scale, pixel size) aren't correct, it will stop the processing of the script and open the ImageSolver dialog. There you can fill in the correct values manually and then WBPP will continue.

Odd. I do not get an error in WBPP with ImageSolver failing.

 

[cloudbait]

Odd. I do not get an error in WBPP with ImageSolver failing.

ImageSolver uses the last image scale information it had when it doesn't find anything in the header. So it won't necessarily fail if the image scale hasn't changed since the last successful solve.