Astronomik Deep Sky filters- colour imbalance

[markse68]

Hi clever peeps,

I have been having some issues getting good colour balance in my imaging since switching from Astronomik 2c to Astronomik Deep Sky LRGB filters. My stars are tending to come out mainly red and green rather than what I think they should be- more orange and blue.

An example is here:

but I also had the same issue with imaging M13 earlier in the year

I came across this analysis of the differences between the 2C and Deep Sky filters that suggests the cut-off requires a compensatory 30% increase in integration time for the blue filter https://www.iceinspace.com.au/forum/archive/index.php/t-171109.html

My question is, do I need to increase my exposure time on the blue filter by 30% compared to the red and green? Or do I need 30% more frames to integrate in Blue? Or should I be able to compensate this somehow in the processing software? I am using Siril. It has a tool called Linear match where you load one filter image and then can "linear match" it to another "master" image (one of the other filters) I did try this and I think it makes quite a lot of difference- still not really right without messing with saturation in GIMP afterwards, but better. I also use the Siril photometric calibration which I thought should compensate the levels based on reference data for the target but this doesn't seem to be able to compensate enough on its own.

What is the best way to deal with this?

Thanks!

Mark

PS this is with an 8" newt, MPCC iii, QSI583, from London- bortle 9

Edited August 27, 2022 by markse68
changed title

[newbie alert]

Any light pollution filters in the imaging train?

[markse68]

8 minutes ago, newbie alert said:

Any light pollution filters in the imaging train?

no nothing else but the cc and LRGB filters.

Mark

[newbie alert]

I use the same filters but I'm more of a narrowband imager than broadband 

[markse68]

Actually I’ve just been reading Martin B’s LRGB imaging primer where he says :

”As you learn the characteristics of your set up you will get a feel for how much you need to adjust the colour channels to deliver a balanced result. Knowing this you can set different exposure times for each colour. My ratio is G:R:B 1 : 1 :1 : 1.4.”

 

I should probably have read his excellent primers before- this is my second year of playing with a camera lol 🤦‍♂️

I’ll  give this a try if it’s still the recommended way to deal with the issue

Mark