ASI294MC users please help!

[scitmon]

Can any ZWO 294MC Pro users outthere please share how they take and process thier calibration frames because I'm having problems calibrating out my amp glow:

 

 

I've taken two lots of darks making sure they have the same length, temp, gain and offset but this amp glow will not go away.  When calibrating in Pixinsight, it seems the only setting that doesn't completely obliterate the detail in my images is the "Optimize" checkbox being checked, ,but evevywhere I read says it should not be.

 

Edited November 3, 2021 by scitmon

[Laurin Dave]

Difficult to diagnose without any data so I'd suggest you post up a raw light, a raw flat. a raw dark and a raw flat dark plus your stacked light, master flat and master dark and flat dark for folks to look at.  A couple of questions...a) do yo use the same capture software to take you lights and calibration frames and b) do you take darks with the camera off the scope and with the senor totally covered? if not you may have a light leak 

[scitmon]

14 minutes ago, Laurin Dave said:

Difficult to diagnose without any data so I'd suggest you post up a raw light, a raw flat. a raw dark and a raw flat dark plus your stacked light, master flat and master dark and flat dark for folks to look at.  A couple of questions...a) do yo use the same capture software to take you lights and calibration frames and b) do you take darks with the camera off the scope and with the senor totally covered? if not you may have a light leak 

Thank you for the reply.

a) yes, all on NINA

b) first time was off with the cap on, second time was on the scope with the telescope lens cap on inside with the light off.  Would that have been sufficient?

 

Light:

2021-10-30_20-32-59__-14.80_120.00s_0030.fits

Dark:

2021-11-01_19-16-43__-14.80_120.00s_0001.fits

Flat:

2021-10-31_10-53-08__-15.40_4.50s_0000.fits

Flat calibrated with a dark:

2021-10-31_10-53-08__-15.40_4.50s_0000_c.xisf

Edited November 3, 2021 by scitmon

[Laurin Dave]

Best practice is to take darks with the camera off the scope and with its sensor cap on to eliminate any possibility of light leaks, will take a look at your data tomorrow..  

[wimvb]

Plastic lens caps can be almost completely transparent to IR light. I take darks with the window side covered with 2 layers of aluminium foil. This works for my ASI294MM

[Laurin Dave]

Morning..  have had a look and the mean level of your dark is three times higher than that of your light (explains why there's nothing left but the bright stars after you calibrate with it ) which is a bit mysterious as temp exposure offset and gain are all the same,  also your light shows no signs of amp glow and looks like it has been calibrated.  I'm not familiar with NINA but is there a possibility that it is outputting calibrated lights?

[scotty38]

I take my darks, flats in fact everything with everything mounted as normal.  If I'm doing darks in the daytime then I may cover the scope as well as the lens cap. It's a WO GT81 so the cap is fairly substantial anyway.

Here's one of my 120s darks for comparison and the average value is a lot less both visibly and as measured in PI. Not saying mine are perfect but there's a definite difference.

It is a 294mc btw.

 

2021-03-03_16-18-01_-10.00_120.00s_0003Target1218.fits

[Laurin Dave]

15 minutes ago, scotty38 said:

I take my darks, flats in fact everything with everything mounted as normal.  If I'm doing darks in the daytime then I may cover the scope as well as the lens cap. It's a WO GT81 so the cap is fairly substantial anyway.

Here's one of my 120s darks for comparison and the average value is a lot less both visibly and as measured in PI. Not saying mine are perfect but there's a definite difference.

It is a 294mc btw.

 

2021-03-03_16-18-01_-10.00_120.00s_0003Target1218.fits 22.31 MB · 0 downloads

Different gain, offset and temp 121,  8, -10 vs 120, 30, -15   may explain that.  @scotty38 what does one of your  raw lights look like  ie is the amp glow clearly visible (I assume it is) 

[scotty38]

13 minutes ago, Laurin Dave said:

Different gain, offset and temp 121,  8, -10 vs 120, 30, -15   may explain that.  @scotty38 what does one of your  raw lights look like  ie is the amp glow clearly visible (I assume it is) 

Not sure if those differences would but only going by the fact the gain is more or less the same. I choose 121 so I'm just over the "special" number. With the cooling at -15 you'd expect less dark current wouldn't you?

I checked a raw light and even zoomed in with a boosted STF I can't see any amp glow to be honest.

Edited November 4, 2021 by scotty38

[Laurin Dave]

Yes the dark current and associated would be less at minus 15,  but the  mean levels in the darks are 1918 vs 520,  almost the same ratio as the offsets ie 30 vs 8 which is what you'd expect

[scotty38]

Yep I didn't spot the offset difference first time round....

[scitmon]

1 hour ago, Laurin Dave said:

Morning..  have had a look and the mean level of your dark is three times higher than that of your light (explains why there's nothing left but the bright stars after you calibrate with it ) which is a bit mysterious as temp exposure offset and gain are all the same,  also your light shows no signs of amp glow and looks like it has been calibrated.  I'm not familiar with NINA but is there a possibility that it is outputting calibrated lights?

I don't see how NINA would calibrate them, there was nothing to calibrate with?  The camera is brand new so it should be taking clean images. 

Perhaps I'll tell NINA to take lights but keep the camera cover on and compare to darks might be worth doing.

I'll have another go at taking the darks tonight and see what happens.

Edited November 4, 2021 by scitmon

[david_taurus83]

Take the camera off the scope and put a metal dust cap on or line the plastic cap with tin foil and take your darks. If your struggling with dark calibration it's the only way to be sure there's no photons hitting the sensor.

[Laurin Dave]

I don't think there's a problem with light leaks. Looks to me as if, despite what the FITS header says, that the offsets are different between the darks and lights (and maybe flat darks and flats although without a flat dark i cant check).   I did a quick test using the dark and calibrated flat to calibrate the light but before doing so subtracted 0.025 from the Dark using Pixelmath, I also added a pedastal of 1000 just in case.   The result is below which looks fine, well pretty good actually, to me.  

A mystery as to why this is happening but at least you can do what I did as a work around.   Only thing I can suggest is to check the driver settings and that both lights and darks and flats were taken using the same driver.

 

 

 

[scitmon]

@Laurin Dave would you mind telling me who you get the "mean level" of a dark?  I'm currently half way through capturing another 30 darks, camera off the scope, cap on and foil covering the cap.

 

Edit: Doesn't matter, i've tested one dark on one light frame and it obliterates the data again.  I really don't understand whats happening.  As the attached pic of the calibrate settings correct?

Edited November 4, 2021 by scitmon

[Laurin Dave]

In Pixinsight  open "Image Inspection" .... "Statistics"  process ..    then select the open Dark image ..   and it'll show the mean level...  it was way higher than the mean level of the light which suggested to me that the offsets were different..  your dark showed no sign of light leakage.    

 

[Stuf1978]

I have a 294MC Pro and for what it's worth I took my darks off the scope with the camera cap on plus a layer of foil. I just matched the temp, gain and offset of my lights and I've never had an issue calibrating out the amp glow  

[scitmon]

out of curiousity, what capture software did you use?

[Stuf1978]

5 minutes ago, scitmon said:

out of curiousity, what capture software did you use?

APT

[scitmon]

Out of curiousity, if I calibrate one dark with another, should it produce a fairly even, clean image?  This is what I get:

 

[Laurin Dave]

Should just be a bit of rando noise left behind at very low ADU...   one for @vlaiv  to opine on, Vlaiv may also have further insight into what's going on here 

[vlaiv]

2 hours ago, scitmon said:

Out of curiousity, if I calibrate one dark with another, should it produce a fairly even, clean image?  This is what I get:

That is ok. That looks as it should for CMOS darks that have amp glow.

Some residual horizontal banding (that averages out with multiple darks) and some noise where amp glow is subtracted.

 

This is very strange by the way. I don't think it is light leak.

Dark looks like proper dark without any added signal - except that it has very high offset.

Fits header shows same settings for it and light.

What driver did you use to capture these images? Native or ASCOM?

[scitmon]

I used the latest native drivers from ZWO. 

[Laurin Dave]

That might be the issue ..  I’d suggest you use the ASCOM drivers and see if that provides consistency between your darks and lights 

[scitmon]

Certainly worth a try, I thought I read somewhere that native should always be used above ASCOM... shame I have to wait for the next clear skies to try it out.

 

21 hours ago, Laurin Dave said:

   I did a quick test using the dark and calibrated flat to calibrate the light but before doing so subtracted 0.025 from the Dark using Pixelmath, I also added a pedastal of 1000 just in case.   The result is below which looks fine, well pretty good actually, to me.  

In the mean time, to try and produce a better image with the data I'm stuck with, can you tell me what Pixel Math formula you used to produce this image?

 

Also thank you all for your input, I appreciate the time you've taken to help me figure this out.