Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Weird glow? What causes it and what is it?

astrophotography dslr
  • Please log in to reply
10 replies to this topic

#1 AstroPepe

AstroPepe

    Explorer 1

  • -----
  • topic starter
  • Posts: 94
  • Joined: 29 Aug 2019
  • Loc: Finland

Posted 24 January 2020 - 05:18 AM

Hi :) I have taken photos of deep sky about 1 year now. It's always exiting to get new images and there is a lots of targets that I can choose. Every time I start to process my images, it shows some weird greenish glow on the left side of my image(modded camera). You can see the left side is greener than the right side(North America nebula) . With stock camera the lefts side of the image is brighter. Is this mysterious glow AMP glow or what? I can easily remove it with photoshop but I have always wondered what could it be? And what causes it?

 

-My setup:

 

Canon 650D stock

Skywatcher eq3-2 pro

Telescope Skywatcher 72ed

 

Camera used for North America nebula:

 

Canon 1100D modded

Filter skytech cls ccd

Attached Thumbnails

  • Picture.PNG


#2 sg6

sg6

    Fly Me to the Moon

  • *****
  • Posts: 6,834
  • Joined: 14 Feb 2010
  • Loc: Norfolk, UK.

Posted 24 January 2020 - 05:41 AM

I cannot see anything/much on the left hands side, or the right either.

Green is usually amp glow, and for whatever reason on one side or the other.

 

Cause is the amps on the sensor chip. The pixel collects the light, effectively changes it over to an electrical charge and when output the amplifiers boost and maybe change the pixel signel. Say change as I recall reading it is something like currant collected to voltage out - maybe the other way round.

 

Each pixel has - I understand - it's own little amplifier. And simply they get warm and we get a signal.

 

There are CMOS sensors in the pipeline that reduce this, not sure if remove it is 100% accurate. Have a search for s-CMOS, and eventually someone will produce a very low currant amplifier on the devices, just not yet exactly. Although ZWO do a 533 (??) device that boasts zero amp glow.

 

Simon Todd has this on it but it reads more a 183 camera review or detail then amp glow.

 

Problem is I suspect caused by much in astrophotography -we are using sevices and items that are not specific to AP. Most sensors are for CCTV etc and so the collection period is maybe a few seconds and often less then a second. So amp glow is not a problem for those periods. We haowever want 30 seconds, 60 seconds and many want 600 seconds. The devices were not really intended for that usage, so produce "problems" when they are made to do it. Your DSLR was really intended for exposures of say 1/100 sec, not what I guess is 30 seconds.



#3 sharkmelley

sharkmelley

    Mercury-Atlas

  • *****
  • Posts: 2,787
  • Joined: 19 Feb 2013

Posted 24 January 2020 - 07:45 AM

I can't see the green you are referring to - not in that small version of the image.

 

In any case, amp glow is usually pink/magenta in colour because it is a phenomenon that affects R, G and B pixels equally.  The R & B channels are subsequently boosted to achieve proper white balance and this is what turns the amp glow to pink/magenta.

 

Mark


  • 17.5Dob likes this

#4 AstroPepe

AstroPepe

    Explorer 1

  • -----
  • topic starter
  • Posts: 94
  • Joined: 29 Aug 2019
  • Loc: Finland

Posted 24 January 2020 - 09:22 AM

Sorry the image isnt perfect bcs i didnt have the original image xD. But yep its there. Thanks for the information about amp glow :)

#5 Michael Covington

Michael Covington

    Author

  • *****
  • Vendors
  • Posts: 5,634
  • Joined: 13 May 2014
  • Loc: Athens, Georgia, USA

Posted 24 January 2020 - 09:24 AM

Dark frame subtraction should remove amp glow.

What is your calibration process?  


  • Greyhaven likes this

#6 nofxrx

nofxrx

    Vendor (HyperCams & Mods)

  • *****
  • Vendors
  • Posts: 5,563
  • Joined: 12 Jul 2005
  • Loc: Melbourne, Florida

Posted 24 January 2020 - 11:10 AM

Sorry, I do not see any glow here. Nor do I believe the 1100D, or ANY Canon DSLR has suffered from (*real*) amp glow in many years (350D era).

Are you sure:

1) it is not a light leak from the camera's LCD screen remaining ON during exposure (the screen is black but the backlight remains ON and there is a small timer in the corner). This is enough to cause a LOT of glow to your images.

1.5) Do not use LiveVIEW for at least 10min prior to starting your imaging as LV heats up internals quickly!

2) it is not an external leak from any light sources outside the camera.

3) maybe this is simply light pollution gradients..?

 

Mark is 100% right, amp glow is always pink/magenta in color. 

 

Good luck!


Edited by nofxrx, 24 January 2020 - 11:11 AM.


#7 AstroPepe

AstroPepe

    Explorer 1

  • -----
  • topic starter
  • Posts: 94
  • Joined: 29 Aug 2019
  • Loc: Finland

Posted 25 January 2020 - 09:22 AM

Dark frame subtraction should remove amp glow.

What is your calibration process?  

I used about 30 dark frames, 30 flatts



#8 AstroPepe

AstroPepe

    Explorer 1

  • -----
  • topic starter
  • Posts: 94
  • Joined: 29 Aug 2019
  • Loc: Finland

Posted 25 January 2020 - 09:26 AM

Sorry, I do not see any glow here. Nor do I believe the 1100D, or ANY Canon DSLR has suffered from (*real*) amp glow in many years (350D era).

Are you sure:

1) it is not a light leak from the camera's LCD screen remaining ON during exposure (the screen is black but the backlight remains ON and there is a small timer in the corner). This is enough to cause a LOT of glow to your images.

1.5) Do not use LiveVIEW for at least 10min prior to starting your imaging as LV heats up internals quickly!

2) it is not an external leak from any light sources outside the camera.

3) maybe this is simply light pollution gradients..?

 

Mark is 100% right, amp glow is always pink/magenta in color. 

 

Good luck!

Sorry for the bad image ill post better image when im on my computer. Maybe you can see from here  https://astrob.in/oz5pvk/0/ lefts side is greener than the right side.



#9 AstroPepe

AstroPepe

    Explorer 1

  • -----
  • topic starter
  • Posts: 94
  • Joined: 29 Aug 2019
  • Loc: Finland

Posted 25 January 2020 - 09:31 AM

Here. I prosessed it with lots of noise reduction, so you can see the greenish colour on the left side corner. Its the same problem as with canon 650d stock camera

Attached Thumbnails

  • Sieppaa.PNG

Edited by AstroPepe, 25 January 2020 - 09:42 AM.


#10 sharkmelley

sharkmelley

    Mercury-Atlas

  • *****
  • Posts: 2,787
  • Joined: 19 Feb 2013

Posted 25 January 2020 - 12:24 PM

Here. I prosessed it with lots of noise reduction, so you can see the greenish colour on the left side corner. Its the same problem as with canon 650d stock camera

I can see the green now.

 

How did you take that image?  Is it a dark frame?  If so, was the camera attached to the scope? 

 

It's odd that according to your description, a 650d stock camera apparently shows the same green effect as a modified 1100D camera.  Do both cameras also have the orange glow at the top left?

 

Mark



#11 AstroPepe

AstroPepe

    Explorer 1

  • -----
  • topic starter
  • Posts: 94
  • Joined: 29 Aug 2019
  • Loc: Finland

Posted 26 January 2020 - 04:04 AM

That image is the same as the north america nebula(light frame). Orange glow is from north america nebula. I just prosessed it with lots of blur (tool in photoshop is dust and scratches)to see main colours/brightness in the image. The green colour is not from nebula and not natural so it must be amp glow?

Edited by AstroPepe, 26 January 2020 - 04:12 AM.



CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics





Also tagged with one or more of these keywords: astrophotography, dslr



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics