Weird interference that occurs 1-2 secs after opening image - Canon 600D

[Arcinox]

Hi, 

Newbie here. I'm in the process of doing some backyard astro-photography with a canon 600D. When I load the images from the SD card on the PC they look normalish (this doesnt happen with the pictures I took earlier but I realised they were in jpeg and not raw format). Then 1 or 2 seconds later the image gets digital interference. Any thoughts? 

Would welcome any other thoughts on improving the 'before' image too. 🤣

Thanks! 

Edited March 24 by Arcinox

[Cornelius Varley]

What software are you using to open the image files ?

[Dr_Ju_ju]

To me, it looks like auto-gain has kicked in, so raising the base noise floor ??

[alacant]

Hi and welcome

Llinks to each cr2 may help us diagnose.
Cheers

[Rallemikken]

First you must check that your image viewer renders the native .cr2-images from Canon without any messing around. Then you must check the EXIF-data of each sub, to get a grip of what's happening. Did you capture with the camera in "M"-mode? Only mode usable on this camera for astro images.

[Elp]

If you're referring to the sudden brightness change it's not interference, it's how computers display raw files in an image viewer.

The colour noise pattern is due to the camera sensor. Cooling helps reduce this though with camera bodies it's more difficult to cool them, if the LCD is articulated moving it off the body can help a little or turn it off. Applying dark frames to the images or bias (Canon usually benefit from a fixed bias value subtraction when calibrating) or dark flats to your flats prior to calibration can also help a little (flats are more to do with removing vignette and dust motes, I've just mentioned it because they can contain bias signal if you haven't subtracted the dark flats from the flats).

But, this is one of the reasons people use cooled astro cameras as this issue is reduced somewhat significantly even prior to calibration.

Edited March 24 by Elp

[Arcinox]

17 hours ago, Rallemikken said:

First you must check that your image viewer renders the native .cr2-images from Canon without any messing around. Then you must check the EXIF-data of each sub, to get a grip of what's happening. Did you capture with the camera in "M"-mode? Only mode usable on this camera for astro images.

 

16 hours ago, Elp said:

If you're referring to the sudden brightness change it's not interference, it's how computers display raw files in an image viewer.

The colour noise pattern is due to the camera sensor. Cooling helps reduce this though with camera bodies it's more difficult to cool them, if the LCD is articulated moving it off the body can help a little or turn it off. Applying dark frames to the images or bias (Canon usually benefit from a fixed bias value subtraction when calibrating) or dark flats to your flats prior to calibration can also help a little (flats are more to do with removing vignette and dust motes, I've just mentioned it because they can contain bias signal if you haven't subtracted the dark flats from the flats).

But, this is one of the reasons people use cooled astro cameras as this issue is reduced somewhat significantly even prior to calibration.

Exactly what must have happened! I opened in photoshop and the sudden changes disappeared! Thanks very much :).