Canon 600D banding

[fortytwo]

Hi everyone,

I recently tried to image Markarians Chain with my WO73Z and Canon 600D and Skytech CLS filter.

My exposures were 161 at 45 seconds at ISO800.

I then went on to capture some data on M13, 56 exposures at 59 seconds also at ISO800.

My question is about the difference in results with similar processing carried out, see below.

The Markarian one has bad sensor banding, the two worst lines I'm used to and just have to clone out, but there is also diagonal colour banding as well.

The frustrating thing is that the M13 image with less data but at a similar point in processing has little of either and I don't know why that might be? (I appreciate that the individual exposures are 15 secs longer but could that make that much difference).

The only other diffrence is that the Markarian Chain image was lower in altitude and therefore more susceptable to the b****y HS2 lights which is why I used the filter.

My last query is that I'm considering having the 600D modified, is there any chance that that might help with the banding or have any other negative effects at all?

 

Thanks again in advance,

Jeff

[Elp]

All calibration files applied to them? Doesn't look like it due to the vignetting.

Edited June 13, 2022 by Elp

[fortytwo]

2 hours ago, Elp said:

All calibration files applied to them? Doesn't look like it due to the vignetting.

Flats, bias and darks all done

[Elp]

I've just checked some of my recent images (same camera, same iso) and they're also there to a degree. Mines IR modded. I also tend to get random dark blotches sometimes. Did you try without the filter for comparison?

Integration time is also quite short, I find dithering if you're autoguiding also helps a lot with dslr quality.

[ONIKKINEN]

You could try running banding reduction in Siril on the calibrated subs before stacking to help with the banding, although im not so sure where the diagonal lines are coming from. Could it be some processing issue if you have removed gradient from the images already? (looks like it)

[SteveNickolls]

Don't know where you are imaging from but if you have light pollution you need far more integration time using the 600Dand even then... Also M13 would have been very much higher up in the sky (70 degrees or so) while the chain of galaxies are around 30 degrees. Good luck.

Cheers,
Steve

[pipnina]

Can you show a stretched individual subframe? If the banding doesn't show (or doesn't show in the same pattern) there, then you could have issues with the stacking algorithm.

Which program are you stacking with? DSS, Siril, PixInsight?

[alacant]

16 hours ago, fortytwo said:

Flats, bias and darks all done

Hi

600d, so it's essential to lose the dark frames. Do not use bias frames taken via the camera, instead simply subtract a constant value of 2048 as the bias value using the software as @ONIKKINENsuggsets, above.

The horizontal bands are in the red and are easily removed:

T

 

The diagonal bands are in the blue and green and almost certainly due to haze or cloud. Simply stack without those frames using e.g. sigma 3-3.

HTH

Edited June 14, 2022 by alacant

[fortytwo]

Thanks for all the replies everyone.

To answer the more general questions, I'm imaging from West London in Bortle 7 -8..

I think I had used Gradient Exterminator.

I'm pretty sure there was no cloud although I can't bee 100% certain.

 

@alacant

That looks useful but I don't understand it, do you have any links to guides at all, I have used Siril for stacking and processing and didn't like it but will give it a go for band removal'

I note you say its essential to 'lose' the dark frames, I assume that is a typing error? and I don't understand what you mean by subtract a constant value of 2048?

If you can provide some clarification I would appreciate it.

Thankyou everyone.

Jeff

[alacant]

8 hours ago, fortytwo said:

links to guides

https://siril.org/

8 hours ago, fortytwo said:

'lose' the dark frames, I assume that is a typing error

Lose: get rid of. Don't include. Don't use dark frames. Forget.... etc.

8 hours ago, fortytwo said:

subtract a constant value of 2048

The 600d's offset:

Edited June 19, 2022 by alacant

[alacant]

8 hours ago, fortytwo said:

links to guides

https://siril.org/

8 hours ago, fortytwo said:

'lose' the dark frames, I assume that is a typing error

Lose: get rid of. Don't include. Without. Forget.... etc.

 

8 hours ago, fortytwo said:

subtract a constant value of 2048

It's the offset on the 600d :