First attempt at SII, Ha, OIII image: Pelican nebula

[Tiny Small]

So this is my first attempt at a three colour narrowband image and I ran into a few problems controlling halos around some of the stars. Quite sure that I'll figure it out in time but any advice would be welcome, as would advice on processing in the Hubble palette.

Shot with the ZWO 178 mm-cool and Altair Astro 60 EDF at 200 gain and 65 offset.

Integration:

Ha; 72 x 300s 

OIII; 59 x 300s

SII; 27 x 600s

Total integration time just under 15.5 hours.

 

 

Edited September 26, 2018 by Tiny Small

[Toxophilus]

Beautifully done!
Halos around narrowband are always a pain to control, but I don't think they detract from the image.

[Adreneline]

42 minutes ago, Tiny Small said:

I ran into a few problems controlling halos around some of the stars

Hi,

Very nice image - I really like it.

You don't mention which processing software you used. I use PS to create Hubble Palette images (Annie's Astro Actions) and run into problems with magenta halos, however, I discovered there is a nice fix for it in PI using a PixelMath script (attached) I found on the PI forum. Apparently the same thing can be achieved using ColorMask under the Script menu but as yet I've not tried that method.

HTH

Adrian

 

remove magenta stars.xpsm

[Tiny Small]

2 minutes ago, Adreneline said:

Hi,

Very nice image - I really like it.

You don't mention which processing software you used. I use PS to create Hubble Palette images (Annie's Astro Actions) and run into problems with magenta halos, however, I discovered there is a nice fix for it in PI using a PixelMath script (attached) I found on the PI forum. Apparently the same thing can be achieved using ColorMask under the Script menu but as yet I've not tried that method.

HTH

Adrian

 

remove magenta stars.xpsm

I stack in either DSS or Astroart (depends if Astroart gives me issues or not), then do the entirety of my processing in PS. I don't use actions though as, coming from a conventional photography background, I'm well versed in editing the conventional way.

[MartinFransson]

Looks great! I have problems with halos myself. Not in the Ha-data but in O3. Haven´t tried S2 yet.

[glowingturnip]

I've just been delving into narrowband processing for the first time too - if you're using Pixinsight, have a look at this tutorial - really nice way to do it and no magenta halos - http://www.arciereceleste.it/articoli/translations/75-narrowband-color-composition-eng

[peter shah]

lovely shot...

[MartinB]

Great first hubble palate NB.  With regard to halos there are any number of methods or removing and you probably need to know a few to deal with different situations.  One curde but very effective way in PS is to apply a blur in photoshop using filter/ dust and scratches to your stretched colour layer.  Don't over do this since you loose colour intensity and don't try to eliminate all the stars.  Layer the blurred colour image onto your luminence using colour as the blend mode.  Then be brutal!  use the clone stamp or healing brush (for smaller stars) over the offending stars and halos.  Most of the time this will work nicely but it can be a bit labour intensive.  

One thing to watch out for when using big blurs is that colour can be stripped from fine filaments.  You can get around this by layering an unblurred colour image over your blurred one and then just revealing the colour filaments using a layer mask.  This is all very un pixinsight and will horrify processing purists!

[Tiny Small]

1 hour ago, MartinB said:

Great first hubble palate NB.  With regard to halos there are any number of methods or removing and you probably need to know a few to deal with different situations.  One curde but very effective way in PS is to apply a blur in photoshop using filter/ dust and scratches to your stretched colour layer.  Don't over do this since you loose colour intensity and don't try to eliminate all the stars.  Layer the blurred colour image onto your luminence using colour as the blend mode.  Then be brutal!  use the clone stamp or healing brush (for smaller stars) over the offending stars and halos.  Most of the time this will work nicely but it can be a bit labour intensive.  

One thing to watch out for when using big blurs is that colour can be stripped from fine filaments.  You can get around this by layering an unblurred colour image over your blurred one and then just revealing the colour filaments using a layer mask.  This is all very un pixinsight and will horrify processing purists!

When I used to shoot fashion and beauty, the skin was edited by non-destructive dodging and burning at pixel level, with a person's face taking a day or two sometimes, so the method you suggest isn't that labour intensive. I think I'll stay away from blurs as it's very easy to mess it up and very hard to get it right, but if there aren't any decent ways of globally controlling the halos then next time, the clone tool around individual stars might be a sensible option or perhaps just painting them out on a colour layer.

One thing that I didn't realise was that a luminance layer can be used with narrowband. Seems obvious when you say it but it just didn't cross my mind. I'm assuming it's usually a Ha layer?

[Tiny Small]

Had a play with using a desaturation layer and some extra curves. Think it has improved it a bit.

 

 

Edited September 27, 2018 by Tiny Small

[jjosefsen]

Lovely details in that image. Can I ask what filters you were using, make and band width?

[Tiny Small]

9 minutes ago, jjosefsen said:

Lovely details in that image. Can I ask what filters you were using, make and band width?

Thanks. I'm using Altair Astro filters. 7Nm Ha, 6.5 Nm OIII and SII.

[Adam J]

Very nice maybe a tad too much noise reduction?

[jjosefsen]

6 hours ago, Tiny Small said:

Thanks. I'm using Altair Astro filters. 7Nm Ha, 6.5 Nm OIII and SII.

Aaah.. I think those are on the "budget'y side" and could very well be the source of those halo's, actually they might be the same as gen. 1 ZWO filters.. (Not sure though..)

My guess is it would be particularly bad in the OIII master??

I just purchased a set og Baader LRGB filters + Ha + OIII and i researched it quite extensively, and alot of the cheaper filters have problems with halo's particularly in the OIII filters.

Edited September 27, 2018 by jjosefsen

[Tiny Small]

4 hours ago, jjosefsen said:

Aaah.. I think those are on the "budget'y side" and could very well be the source of those halo's, actually they might be the same as gen. 1 ZWO filters.. (Not sure though..)

My guess is it would be particularly bad in the OIII master??

I just purchased a set og Baader LRGB filters + Ha + OIII and i researched it quite extensively, and alot of the cheaper filters have problems with halo's particularly in the OIII filters.

They're about the same price as the standard baader ones (£250 for three 1.25 inch filters Vs £270 for the baaders) and the o3 and S2 have a narrower range than the baader filters. 

Edited September 28, 2018 by Tiny Small

[jjosefsen]

7 hours ago, Tiny Small said:

They're about the same price as the standard baader ones (£250 for three 1.25 inch filters Vs £270 for the baaders) and the o3 and S2 have a narrower range than the baader filters. 

Yeah you are right actually, my bad.. But is the Halo more significant in one particular band i wonder?

[Tiny Small]

12 minutes ago, jjosefsen said:

Yeah you are right actually, my bad.. But is the Halo more significant in one particular band i wonder?

I replied when I was half asleep last night, so I apologise for missing this bit out: the individual channels look fine, but the Ha has physically bigger stars and i think that, combined with aggressive stretching is what is causing the halos. I think it's a sub length and processing  issue. I'll need to take a look at some individual subs.

[ollypenrice]

I think that's lovely. There is no getting away from the subtlety of genuinely three channel colour images. 

Olly

[Tiny Small]

Cheers Olly. I have to say, getting the right balance is a bit trickier than with LRGB. More rewarding though.

[neltek]

which mount are you using?

 

[Adam J]

Removed reply as I just noticed this is a zombie thread. 

Edited July 2, 2020 by Adam J