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Demonperformer

good news ... bad news

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The good news is that last night, for the first time, I got my finder-guider working, which enabled me to take some 300s subs. The bad news is that this has revealed some horrendous amp glow on my new camera. This also shows up well on my 300s dark frame. This prompts a number of questions (some of which may become obsolete dependant upon the answers to others):

(1) This camera was purchased in December last, so is still under warranty. Should I be trying to get it fixed? This will no doubt entail me being without a monochrome camera for quite a while.

(2) Is there some solution that I can do myself? I have not noticed this problem with shorter subs, which will probably be the norm for this camera, but if there are steps I can take they may be worth considering.

(3) As the amp glow shows up on the dark frame, should this be eliminated when I use one? I didn't want to waste an hour doing a dark frame last night as it was only really a test-evening of a few things due to the presence of that friend of all imagers; the moon. However, I have now got one and would be able to use that on subsequent sessions (assuming I used the same settings).

I did as much playing with Sharpcap's histogram as I could to get a semi-reasonable result, but even so it is still obvious.

Thanks.

dark frame.png

Stack_12frames_3600s.png

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Are you sure that’s amp glow, that looks more like a light leak into the camera...it’s very uniform almost like an oversaturated star, and amp glow does not normally present like that....well not in my experience anyaway.. :)

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take a bit of sticky tape next time you use the camera and stick it down the place where join in the camera body and see if you still get it, ive a 1100d what do the same a bit of tape fixed it for me. to me it deff looks like a light leak. charl.

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That is not amp glow!   check your installation, you have a leak!    Henry b

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 I  believe amp glow is 'normal' in  these new cmos cameras and you just have to take darks. Also, I believe it's better to take many shorter subs.

Louise

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Looks just like the AMP GLOW I have with MY ZWO ASI 183mm Pro camera.

https://astronomy-imaging-camera.com/tutorials/what-is-amp-glow.html

From the research I have done on SGL and other sites. I set the GAIN at 111 for LRGB and 200 for NB.

I create a library of DARKS at several time settings that I will be using. i.e 10s, 30s, 60s, 120s, 300s. Gain 111 and again with Gain 200.

I take Flats around the same time of imaging, either beginning or end.

Process the Lights, Dark and Flats. I have seen some use 100 lights at 1 minute and 30 of each dark and flats. However, I do try to use equal lights/flats/dark. Maybe experiment here.

DONT use BIAS. They don't help :)

From this one should enjoy glow free images.

Good luck :)

 

Dave.

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Don't forget, DARKS can be done anytime. I create my DARK library in the daytime. The camera does not need to be attached to scope. I sit mine next to my PC with its nose cap on in a dark part of the room. Once made, use it for the next 3 to 6 months. or until bored :)

 

Dave.

Edited by Star101
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I was just about to post a 300sec sub taken in a camera light-proof changing bag showing the same glow when I read your post. Good (relative term!) to know darks will sort the issue. I will get going on my library.

As a matter of interest,  why 111 & 200?

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As others have said, this does look like Amp Glow. I've heard the Amp Glow from an ASI 183 is pretty horrendous looking at first glance. But don't worry, it calibrates out just fine as long as you make a good set of Darks.

As an aside - i do know that AstroPixelProcessor recently added a feature to help with calibration of cameras with really extreme amp glow. See here:

https://www.astropixelprocessor.com/community/release-information/astro-pixel-processor-1-062-ready-for-download/

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I have now produced my dark library  (with one omission which I will try to get done tomorrow): 183MM & 183MC, temp -15, gain 120 (15, 30 & 60s) + gain 180 (1, 2 & 5 mins).

During the process I discovered that my stack above used a flat taken previously without the filter - will maybe have a go at redoing it if I get the time.

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Having completed my 5m darks with the colour camera, it appears that it has exactly the same amp glow as the monochrome. Don't know for sure, but I'm guessing they are exactly the same camera, just with the bayer matrix added to the colour one? But that would make it strange that the colour one (with the additional bit) is actually £100 cheaper.

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It's amp glow with an ASI183 or variant. I had that and couldn't get rid of it no matter what I did. I think the wretched thing is a write-off for serious imaging. Pity, as it's a good fit for my 80mm f/4.4.

The only success I had was when there was a meridian flip between subs, so sigma stacking could see it as an artifact and remove it.

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I've followed a few threads on Cloudy Nights, and apparently 10 min subs are the limit for the 183. Any longer and the amp glow begins to become uncorrectable. Though you should be able to go for as long as 10 min. 

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I'd not seen this before.  That first image is quite alarming.  It looks like there's some sort of IR source sitting right on the edge of the sensor.

James

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for what it's worth, back when I started and was using an old unmodded Nikon with serious amp glow, I was never able to calibrate it out even though both darks and lights showed it - temperature differences between the darks and lights meant they would never match, and the longer in total I imaged for, the hotter it would get.

I'd assume this is better with temperature controlled cameras though... ?

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Much. I did some 300s NB subs at high gain on the MC the other night and the darks almost get rid of the amp glow completely. The 120s subs did get rid of it completely. Might investigate to see how long I can go ...

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