Testing my new setup - Heart Nebula

[SyedT]

Having recently acquired a WO GT81, I've been sorting out teething issues to make sure everything is working well before the nights start drawing in. Did a test run for the Heart Nebula and figured out my spacing was off as I could see significant trailing at the peripheries; seemed unlikely to be due to guiding as the image centre was fine, and it turns out I was correct; increasing the spacing by 25mm has done the trick. Processed the dataset anyway, turned out ok I guess.

Ha 25x300s + OIII 15x300s + SII 12x300s - Total integration time 4h20mins.

I'm now starting to go down the route of lower exposure time + higher gain + stacking more subs to recover more bits; it'll drop dynamic range but you can't have it all I guess, especially in the UK's weather. Hopefully a Heart & Soul mosaic is on the cards with 180s subs, we'll see how that goes with OIII/SII though!

This is also the first time I've done a tricolour narrowband combination, and it's proven to be fairly tricky! I'm fairly happy with the colour in this one as I wanted to keep the processing as soft as possible, but lots to learn still.

[Uranium235]

The data looks great! But, I think the colour is a bit off.

If you want a foolproof method for SHO images, follow this tutorial:

http://bf-astro.com/hubblep.htm

It leads to you to the "classic" hubble colour (blue/gold), but there is nothing to stop you from using the selective colour to achieve different colour schemes. Just ensure the background is correct whatever colours you employ (your above image has too much blue in the background).

[gnomus]

I agree with Uranium235 about the colours.  I find getting the colour balance 'correct' in these SHO images is often tricky.  The centre of the image looks really good.  You still have some issues in the corner - these are all pointing towards the centre which suggests to me that they can be fixed by getting the spacing correct.  I remember seeing a diagram that told you whether you needed more or less spacing depending upon the type of elongation you had.  But I cannot remember which way round it was and for the life of me I cannot recall where I saw it.    

[gnomus]

10 minutes ago, gnomus said:

.....I remember seeing a diagram that told you whether you needed more or less spacing depending upon the type of elongation you had.  But I cannot remember which way round it was and for the life of me I cannot recall where I saw it.    

OK - I found it (as is often the case @swag72 comes to the rescue).  Looks like you need a bit more spacing:

https://stargazerslounge.com/topic/294708-stars-dont-look-right-help/?do=findComment&comment=3226353

[SyedT]

12 hours ago, Uranium235 said:

The data looks great! But, I think the colour is a bit off.

If you want a foolproof method for SHO images, follow this tutorial:

http://bf-astro.com/hubblep.htm

It leads to you to the "classic" hubble colour (blue/gold), but there is nothing to stop you from using the selective colour to achieve different colour schemes. Just ensure the background is correct whatever colours you employ (your above image has too much blue in the background).

Thanks for the link! I've tried that method but I'm trying to do a lot of my processing in Pixinsight. Any Hubble palette tutorials for that available to get a good blend? Not satisfied with any I've used so far, been trying a few different ones in PixelMath.

2 hours ago, gnomus said:

I agree with Uranium235 about the colours.  I find getting the colour balance 'correct' in these SHO images is often tricky.  The centre of the image looks really good.  You still have some issues in the corner - these are all pointing towards the centre which suggests to me that they can be fixed by getting the spacing correct.  I remember seeing a diagram that told you whether you needed more or less spacing depending upon the type of elongation you had.  But I cannot remember which way round it was and for the life of me I cannot recall where I saw it.    

Thanks! As mentioned in my original post, I've already fixed the issue; I knew it was a spacing issue because there was trailing only at the edges, and figured I needed ~25 mm of extra spacing but there was some uncertainty as to the exact value; managed to find a Baader Varilock which has solved all issues very nicely. Nice round stars in all corners now.

[gnomus]

2 hours ago, SyedT said:

Thanks for the link! I've tried that method but I'm trying to do a lot of my processing in Pixinsight. Any Hubble palette tutorials for that available to get a good blend? Not satisfied with any I've used so far, been trying a few different ones in PixelMath.

Thanks! As mentioned in my original post, I've already fixed the issue; I knew it was a spacing issue because there was trailing only at the edges, and figured I needed ~25 mm of extra spacing but there was some uncertainty as to the exact value; managed to find a Baader Varilock which has solved all issues very nicely. Nice round stars in all corners now.

Sorry for misunderstanding.  I read your post to mean that this image was done after the fix.

[SyedT]

15 hours ago, Uranium235 said:

The data looks great! But, I think the colour is a bit off.

If you want a foolproof method for SHO images, follow this tutorial:

http://bf-astro.com/hubblep.htm

It leads to you to the "classic" hubble colour (blue/gold), but there is nothing to stop you from using the selective colour to achieve different colour schemes. Just ensure the background is correct whatever colours you employ (your above image has too much blue in the background).

Did a bit of editing. Getting more of the blue/gold scheme now, but starting to get a lot of red at the peripheries. Any suggestions? I know I need to collect more data anyway, as this was just a test run.

 

28 minutes ago, gnomus said:

Sorry for misunderstanding.  I read your post to mean that this image was done after the fix.

Not a problem at all, appreciate your help. In the first instance I actually bought an 80mm extension tube initially as I couldn't get focus. Then once I bought the spacer afterwards I found that the extension tube became redundant as the spacer was all I really needed. It really can become an expensive hobby quite quickly!

[Allinthehead]

Some lovely detail. I think your first image is nicer. Even balancing the colours will create a more pleasing image.

[bob-c]

very nice image.

[MartinB]

Syed, I hope you don't mind me suggesting this but, have you ever tested your colour vision.  Other than the star issue mentioned your luminence is excellent.  The colour problem is predominantly with the background.  Your first image has a magenta bias and in the second it is green.  I have tweeked the first pic to give a fairly neutral background.

 

 

[SyedT]

1 hour ago, MartinB said:

Syed, I hope you don't mind me suggesting this but, have you ever tested your colour vision.  Other than the star issue mentioned your luminence is excellent.  The colour problem is predominantly with the background.  Your first image has a magenta bias and in the second it is green.  I have tweeked the first pic to give a fairly neutral background.

 

 

Hi Martin,

I don't mind at all! I welcome all feedback to be honest, narrowband is tricky since I'm so new to it all. I do have difficulty differentiating between shades of closely-matched shades of colour. In the first image, I forgot to run background neutralisation which I know is essential. For the second one, I masked the edges in photoshop as it was becoming red-dominant, and overdid it; now that I look at it again, it definitely does look like it has a green bias.

I'm finding that with using the Photoshop selective colour method, it becomes difficult to neutralise the background adequately. Any tips?

[MartinB]

27 minutes ago, SyedT said:

Hi Martin,

I don't mind at all! I welcome all feedback to be honest, narrowband is tricky since I'm so new to it all. I do have difficulty differentiating between shades of closely-matched shades of colour. In the first image, I forgot to run background neutralisation which I know is essential. For the second one, I masked the edges in photoshop as it was becoming red-dominant, and overdid it; now that I look at it again, it definitely does look like it has a green bias.

I'm finding that with using the Photoshop selective colour method, it becomes difficult to neutralise the background adequately. Any tips?

Provided you leave yourself a little room in all three channels to the left of the histogram prior to doing selective colour adjustments you can use levels to adjust each channel separately afterwards.  You can either judge using your eyes or by looking at the histograms.  You can set the histogram tab to show individual channel colours