Iris Nebula

[Rodd]

I have been working on the Iris for a few weeks now--accumulating data when the sky clears.  My plan was to capture equal amounts of RGB and then about 3x the amountbof lum that I got for the other channels.  I got about 8 hours of red, 8 hours of green, but only about3.5 hours of blue and no lum yet--but I created a synthetic luminance out of the RGB subs.  My question is--will I see a sugnificant improvement if I stick with the plan and collect a few more hours blue and 10-15  hours of luminance.   Dim targets like the surrounding dust alaway appear noisy for me--regardless of the amount of data, which severly limits my stretch.  I have pushed this image as far as I can without resorting to copius amunts of noise suppression.  So, a but more blue and a nightor two of lum--or call it a day?

TOA 130 with ASI 1600

Red: 241 120 sec

Green: 236 120 sec

Blue: 93 120 sec

Lum: All RGB subs integrated

[alan potts]

Lovely image there Rodd, almost looks like it's smoking, must try this one sometime, been beaten in by cloud for a couple of hours so that's it for me tonight.

Alan

[Adam J]

I think that lum will help personally i would say that proper luminescence is the way to go here, the dust is reasonably balanced between R,G & B channels so will benefit fully from using a lum filter.

[Rodd]

1 hour ago, alan potts said:

Lovely image there Rodd, almost looks like it's smoking, must try this one sometime, been beaten in by cloud for a couple of hours so that's it for me tonight.

Alan

Thanks Alan.  I find the Iris (and nearby ghost) difficult to do well.   I have gotten in the habit of blaming my sky, but am not completely convinced it’s not my processing skills that are to blame😄

Rodd

[Rodd]

1 hour ago, Adam J said:

I think that lum will help personally i would say that proper luminescence is the way to go here, the dust is reasonably balanced between R,G & B channels so will benefit fully from using a lum filter.

I normally would agree from a color balance perspective, but I am not so sure from a noise perspective. That’s the primary reason I collect more than a couple of hours each of RGB per image—to reduce noise.  When I collect much less of a color than the others, it shows up on the histogram as a different shape curve—usually really flat but very wide.  In this case the rgb curves do look similar, so you are right about not really needing more blue for blue chroma sake.  But it’s the noise that troubles me.  If the seeing not great, I will probably add some blue. If the seeing is good i’ll Go for lum. Thanks for your input!

Rodd

[Rodd]

3 hours ago, Adam J said:

I think that lum will help personally i would say that proper luminescence is the way to go here, the dust is reasonably balanced between R,G & B channels so will benefit fully from using a lum filter.

Thnks to a few suggestions from Adam, I have modified the image a bit.  While still not a completed project--it is shaping up.  Thanks,

Rodd

[wimvb]

A great image already, Rodd. If light pollution isn't too bad, go for the luminance. Otherwise shoot more blue and create a synthetic luminance. Good RGB filters tend to limit LP, because of a gap between the R and G filters at the Na and Hg emission lines. 

[Rodd]

14 hours ago, wimvb said:

A great image already, Rodd. If light pollution isn't too bad, go for the luminance. Otherwise shoot more blue and create a synthetic luminance. Good RGB filters tend to limit LP, because of a gap between the R and G filters at the Na and Hg emission lines. 

Thanks Wim.   Yeah I have noticed less LP effects on RGB.  I made a synth lum on this... but it probably isn’t as good as it could be without the rest of the blue.  I must say the impact on the image was slight, noticeable though.   I guess it will depend on seeing.  If I can manage to get FWHM values down around 2 or maybe even less than 2 (quite rare for me) I think I will go with the lum. 

Edited September 30, 2019 by Rodd

[astro mick]

Hi Rodd.

Yes I can see you have pushed the RGB to the limit,whils,t trying to keep the noise down.The noise is still slightly there in the background.

So maybe as the others say,perhaps the Luminance is the way to go.Then perhaps you would,nt have to stretch the RGB as much.

Its your usual exerllent image,but it could be bettered by yourself I,m sure.

I,m no expert Rodd,so limited advice.

Mick.

[Rodd]

3 hours ago, astro mick said:

Hi Rodd.

Yes I can see you have pushed the RGB to the limit,whils,t trying to keep the noise down.The noise is still slightly there in the background.

So maybe as the others say,perhaps the Luminance is the way to go.Then perhaps you would,nt have to stretch the RGB as much.

Its your usual exerllent image,but it could be bettered by yourself I,m sure.

I,m no expert Rodd,so limited advice.

Mick.

Sounds about right Mick, thanks!

Rodd