NGC891

[MrsGnomus]

It proved a bit of a struggle gathering data on this one.  It has been variably misty here, and there were many nights when we set off only to be enveloped in fog a short time later.  We ended up throwing away around 3 hours worth of subs, and not all of what was kept was 'ideal'.  

Esprit 120; QSI690 with Astrodon LRGB filters; Mesu 200

Lum: 52 x 5 mins = 4 hours 20 minutes 

R, G & B: 12 x 5 mins each = 3 hours

Total = 7 hours 20 mins

Processing in PI and PS, whilst being 'encouraged' by @gnomus

All C&C welcome

[Uplooker]

Good evening Mrsgnomus,

That looks very good indeed, well done.

I must admit that I vaguely remember seeing a post from you the other day and thinking "Mmmm, is that any relation to gnomus?". Well now I have my answer

Does that also mean you know how much all that equipment actually cost?

[laudropb]

Very nice image as a reward for all your efforts.

[wimvb]

Great image, fog or no fog.

The only distraction is the bright star lower right.

Thanks for sharing and Happy New Year to you and mr Gnomus

[gnomus]

6 minutes ago, wimvb said:

Great image, fog or no fog.

The only distraction is the bright star lower right.

Thanks for sharing and Happy New Year to you and mr Gnomus

Thanks for the kind comment.  Yes.  We think that is HD 14771 - a 6th magnitude star.  Apparently some folk use it as a visual landmark for locating the galaxy.  I'm never very sure how much one should try to hold back these bright stars.  

[MrsGnomus]

11 minutes ago, Uplooker said:

Does that also mean you know how much all that equipment actually cost?

Yes - the question is "Does he?"

[ollypenrice]

A crisp image! In a target like this, short on faint fuzzies, you don't have to use the same stretch for the galaxy as for the stars so long as the background sky is identical. Just a thought. Happy new year to all chez Gnomus!

Olly

[MrsGnomus]

13 minutes ago, ollypenrice said:

A crisp image! In a target like this, short on faint fuzzies, you don't have to use the same stretch for the galaxy as for the stars so long as the background sky is identical. Just a thought. Happy new year to all chez Gnomus!

Thanks for the advice Olly. I may have another play tomorrow if I can escape from the kitchen for a while! Traditional Gnomus household New Year's Day dinner has to take priority though or there will be mutiny from the 3 (not so) minignomuses. 

[ollypenrice]

The fact that I'm out imaging tonight on new year's eve is provoking smouldering undertones of potential mutiny here as well! Solidarity...

Olly

[steppenwolf]

If it wasn't cloudy/foggy here I'd be out imaging too. However at midnight I will be outside regardless - playing the pipes

[ollypenrice]

5 minutes ago, steppenwolf said:

If it wasn't cloudy/foggy here I'd be out imaging too. However at midnight I will be outside regardless - playing the pipes

You know what they say: ' A gentleman can play the bagpipes - but doesn't!'

Olly

[steppenwolf]

1 minute ago, ollypenrice said:

You know what they say: ' A gentleman can play the bagpipes - but doesn't!'

Ah but I'm no gentleman as proven by the fact that I forgot the main event - I do like this image a lot, one in the eye for the fog!

[MrsGnomus]

11 hours ago, ollypenrice said:

A crisp image! In a target like this, short on faint fuzzies, you don't have to use the same stretch for the galaxy as for the stars so long as the background sky is identical. Just a thought. Happy new year to all chez Gnomus!

Olly

Happy New Year everyone.  As is often the case the @ollypenrice suggestion paid dividends.  Is this the sort of thing you had in mind, Olly?

[ollypenrice]

Yes. What I tend to do with 'galaxies in starfields' is do a hard stretch of everything with my regular background of 23/23/23 in RGB. I then do a gentle stretch looking only at the stars but also ending up with a 23/23/23 background. I then put the soft stretch (counter-intuitively) on top and, (also counter-intuitively) set the opacity to zero so it can't be seen. I then take the eraser and run it over the main galaxy and any faint fuzzies in the picture. When I bring the opacity back up I have the small stars and the faint fuzzies ready to be flattened into one image.

Olly

[gnomus]

Thanks for the tip @ollypenrice.  To get our 'soft stretch' up to 22/23, we ended up with a histogram that had a gap to the left.  Like:

I assume that is correct.  Our 'hard stretch' produced a more 'fleshed out' histogram.  We put the hard stretch on top, masked it, and then let the galaxy and faint fuzzies back in through the mask.  (I think this amounts to the same thing.) 

[Barry-Wilson]

Well done Mrs Gnomus - a lovely and naturally processed galaxy with some great detail in the dust.  Lots of faint fuzzies in the nice flat background.  Terrific.

[ultranova]

very nicely done indeed, very natural looking take

on this Galaxy.

well done

Paul

[MrsGnomus]

49 minutes ago, Barry-Wilson said:

Well done Mrs Gnomus - a lovely and naturally processed galaxy with some great detail in the dust.  Lots of faint fuzzies in the nice flat background.  Terrific.

 

46 minutes ago, ultranova said:

very nicely done indeed, very natural looking take

on this Galaxy.

well done

Thank you both for the encouraging feedback. 

[ollypenrice]

2 hours ago, gnomus said:

Thanks for the tip @ollypenrice.  To get our 'soft stretch' up to 22/23, we ended up with a histogram that had a gap to the left.  Like:

I assume that is correct.  Our 'hard stretch' produced a more 'fleshed out' histogram.  We put the hard stretch on top, masked it, and then let the galaxy and faint fuzzies back in through the mask.  (I think this amounts to the same thing.) 

You can avoid this situation (though whether or not it needs avoiding I don't know!) by doing a 'starfield stretch' like this:

I'm selling it here for core control but it will work as a background and stars stretch as well. The straight line shouldn't be sagging, by the way. It should be straight but I'm too idle to fix it! Oh, one other thought: making your starfield and stars out of RGB only can be advantageous in terms of obtaining small, colourful stars. I've done that on a few galaxy images.

Olly

[gnomus]

1 hour ago, ollypenrice said:

You can avoid this situation (though whether or not it needs avoiding I don't know!) by doing a 'starfield stretch' like this:

 

Thanks again Olly.   First off, we did just use the RGB file for the starfield.  I thought we had done this because of bone-idleness, so it's reassuring to know that we did it for considered reasons.  

I just had a go at your stretch on just the RGB stack.  I ended up with a similar result to my Levels stretch method, except for that nuisance star HD 14771 (in the bottom right corner).  It developed a sort of halo around it, like this:

And I'd only got the background to 14 by this stage.  (I do wonder if a lot of the problems were down to the misty conditions much of this was shot in.)

Furthermore, the histogram really didn't look an awful lot different (that is, it still had the gap):

 

[ollypenrice]

1 minute ago, gnomus said:

Thanks again Olly.   First off, we did just use the RGB file for the starfield.  I thought we had done this because of bone-idleness, so it's reassuring to know that we did it for considered reasons.  

I just had a go at your stretch on just the RGB stack.  I ended up with a similar result to my Levels stretch method, except for that nuisance star HD 14771 (in the bottom right corner).  It developed a sort of halo around it, like this:

And I'd only got the background to 14 by this stage.  (I do wonder if a lot of the problems were down to the misty conditions much of this was shot in.)

Furthermore, the histogram really didn't look an awful lot different (that is, it still had the gap):

 

I tend to think that you should close the gap (reset the black point) and stretch again. That way you'll give yourself the full dynamic range for the stars - which might be a help. ¨Probably won't make a jot of difference though!

Olly

[PatrickGilliland]

Nice work Mrs G - I like this one set in the context of the background and other fuzzies.

Paddy

[johnrt]

Nice work, I'm a fan of the original version more I think, the bigger stars sets the galaxy in a little more context for me, but both are excellent!

[MrsGnomus]

10 minutes ago, johnrt said:

Nice work, I'm a fan of the original version more I think, the bigger stars sets the galaxy in a little more context for me, but both are excellent!

Thanks John.  I think Olly was telling us that we hadn't quite stretched the stars enough in the second version.  We like small stars, but perhaps you can take this too far.  Here is a slightly more stretched star field - but without the bloat present in V1:

[steppenwolf]

I like star 'suppression' in narrowband images as we have already decided to accept 'false' colour so from there on anything goes. For RGB, where we are aiming for 'natural' colours I prefer to see a more balanced view of the stars so if the stars are bright, they should be obvious in the image. The only exception to this for me is taming a star like Alnitak which is not only bright but it destroys detail in the main event so I can be flexible on this point