Blocks in my image

[wsteel33]

Hi Guys

I have recntly been playing with a new portable rig (Canon 600D with the kit lens operating at 100mm on a Skywatcher AzGTi with equitorial firmware).

It's looking very promising for taking on visits to dark skies.

I took a couple of images the other night and noticed this blocking in the background during processing.

The attached image was preprocessed in Siril (Flats, Darks and Bias frames all used) with photometric colour calibration and background extraction applied.

I then moved it to PS where I did a couple of curves (one Arcsinh10 and one gentle manual one) with a couple of levels adjustments.

The stars were then removed with StarXTerminator.

Attached is the starless image.

Can anyone tell me what is causing the blocks seen in the image and if they know any processes I can follow to fix/mitigate them.

Thanks in advance for any advice or guidance you can offer.

Wayne

Edited December 30, 2022 by wsteel33
Smaller image file

[alacant]

Hi

600d, so dither at least 10 pixels between frames and lose both dark and camera sourced bias. Instead, simply pre-process by subtracting the offset (2048) from both the flat and light frames before registration. Stack with one of the clipping algorithms. Siril makes these tasks easy.

Working with the linear stack, crop the frame edges and extract the background before photometric colour calibration.

That will clean the background and so go some way to avoid artefacts introduced by other software😉

Cheers and HTH

Edited December 31, 2022 by alacant
jefe

[wsteel33]

On 30/12/2022 at 22:25, alacant said:

Hi

600d, so dither at least 10 pixels between frames and lose both dark and camera sourced bias. Instead, simply pre-process by subtracting the offset (2048) from both the flat and light frames before registration. Stack with one of the clipping algorithms. Siril makes these tasks easy.

Working with the linear stack, crop the frame edges and extract the background before photometric colour calibration.

That will clean the background and so go some way to avoid artefacts introduced by other software😉

Cheers and HTH

Brilliant

Thanks, I will try this.

thanks for the advice