Heart, Soul and Double Cluster - advice on processing

[Stub Mandrel]

Help!

80% of 115 60-second RGB subs with Zeiss 135mm f3.5 Sonnar.

I know I have basically got some really good RGB data here, but I seem to have a problem with red stars. I've done what I can but I am sure I can do more. I also need to look at ways of reducing background noise further. I'm trying a second stack without bilinear debayering.

[alacant]

Hi. Nice shot. I'm in the same situation with my takumar version. I can't lose the red without screwing the rest of the colours. Yours looks more natural. For the noise, in StarTools you could decrease the initial grain % and increase the read noise compensation and smoothing. Or whatever that's called in other processing. HTH 

[StargeezerTim]

I've got the same image from last night to process!

You could make a star mask and adjust the colours. in ps you can adjust just the reds so you can change the colors etc without affecting the other stars. it also looks like the red is part of a gradient so you try flattening the field with DBE or whatever you have. hth. Tim.

[Stub Mandrel]

It's interesting, this one from 2014 shows the same effect. Suggest it isn't caused by light pollution. I notice these are fainter stars and perhaps they are shining through the dusty nebula and are really red?

 

[Stub Mandrel]

And here's another try with LESS noise reduction but clevererness on the levels and I boosted the fainter stars (because alacant's image is starrier than mine!).

[Stub Mandrel]

I those two above look terrible now!

I looked at the subs and decided only about 50% weren't affected by cloud, so I reduced the stacking percentage:

 

[Knight of Clear Skies]

To my eye at least, the previous image is a little too saturated and perhaps over-sharpened, while the most recent has some very red stars at lower right.

I usually find Starfields the hardest things to process and rarely get them quite how I'd like. Something I've been doing recently is to create a star mask in StarTools and adjust them in the colour tool. I cap green and set the dark saturation very low while boosting the overall saturation. This increases the colour in the brightest stars, compensating for the desaturation on longer exposure effect. I also think it helps create an illusion of depth and mimics the eye's lack of colour sensitivity to dimmer objects. To boost Ha regions I use the selective colour tool in PS, dropping cyans and sometimes adjusting the blacks.

2 hours ago, Stub Mandrel said:

It's interesting, this one from 2014 shows the same effect. Suggest it isn't caused by light pollution. I notice these are fainter stars and perhaps they are shining through the dusty nebula and are really red?

 

I used to think the brown in the centre and lower of that image was dust, but now I doubt it. It's not in my newer one, and I remember that back in 2014 I left the eyepiece cover off with some lights on in the house behind me, so I suspect it may be stray light. Looking at star counts may give a truer indication of where the dust lies.

3 hours ago, alacant said:

Hi. Nice shot. I'm in the same situation with my takumar version. I can't lose the red without screwing the rest of the colours. Yours looks more natural. For the noise, in StarTools you could decrease the initial grain % and increase the read noise compensation and smoothing. Or whatever that's called in other processing. HTH 

I'm fairly sure this is a problem with the initial colour balance, I often struggle with this. Sometimes DSS gives me something easy to work with, sometimes it's a nightmare. I had a quick try with your jpg and got something more natural looking by stretching down the reds, so that the bar isn't that much wider than the blues and greens.

Hope that's some help.

[Stub Mandrel]

Ok :-)

Here's yet another try with less saturated stars! But looking at yours, I think I'll try a less stretched version and see if I can get the stars to be brighter.

[StargeezerTim]

21 hours ago, Stub Mandrel said:

It's interesting, this one from 2014 shows the same effect. Suggest it isn't caused by light pollution. I notice these are fainter stars and perhaps they are shining through the dusty nebula and are really red?

 

Here is mine from a couple of nights ago. It doesn't have the same resolution but suggests to me that a gradient is responsible for the colours as there is no similar variation on mine...unless I just failed to pick it up! I did flatten it with DBE as I had a red colour gradient on both left and right edges.