Tulip nebula in Hubble palette

[JR]

Same one shot colour data as before but different processing.

I used a LRGB combination with red channel (Ha in monochrome) for luminance, which brightens the image and adds detail. The resulting RGB channels were extracted and mapped to Hubble palette. Stars were almost entirely removed to give better visibility to nebula and gas clouds.

James

[trevsie7]

James, that's a vast improvement. You have extracted a lot more detail this time

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[tcos...@gmail.com]

Hi James
That's a definite improvement and reducing the stars has helped to make the nebula more visible. My wife was rather derogatory about me removing stars in my last image, but it is necessary in these narrowband nebula images because the stars can overwhelm the subject i.e. the nebula, if they are not properly controlled. It can be a very time consuming exercise needing quite a lot of experimentation and the resultant artefacts have to be dealt with too, but worth it in the end.
KR
Tim

[John Mills]

Hi James,

That's a very good image using a one shot camera and more so with the
short exposure times you were using. I can't remember if I posted my
image of the Tulip nebula (SH2-101) taken a few years ago using Ian
King's remote 10" RTC in Nerpio, Spain? If not, it was this one.

This was taken over several nights using a QSI camera fitted with Ha,
OIII and SII filters. So quite a few hours worth of 600s subs through
those filters. It was quite a difficult object to process I recall and
done using Photoshop CS2 - the free to download version ;-)

ATB John

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[JR]

Hi John

I hope all is well with you.

Your image is superb. If I could get close to that I would be more than happy.

Thanks for your kind comments as well. You have summed it up well. OSC and limited data. I have weighed up the monochrome route several times but the reality is that the number of nights I could use it seem to increasingly limited by weather and the possibility of collecting data on several sessions seems to be decreasing.

With other things going on and the weather, by the time another clear night comes round the object might well no longer be visible behind the many trees we have, the house etc. I aim for the best I can do in the circumstances and doing better with experience.

all the best

James

Sent from my iPad

> On 12 Oct 2021, at 16:26, John Mills <ejm...@millseyspages.com> wrote:
>
> Hi James,

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> <SH2 101.jpg>

[William Bottaci]

"It's (not) full of stars!" Dave, from 2001 (but screened in 1968).

I wondered where they had gone and was thinking of how I could ask ... yes, I agree that with so many they can get in the way. Begs the question, please; how do you get rid of them?

I like stars (though not in the same way some people like trains :). An idea; how about a .gif of 2 layers with the stars rounded up and on an overlay?

Nice nifty processing.

John, your image could hardly be better. Nice colours and contrast. Unfortunately I share with James; monochrome with filters, though the better way, bit beyond my practical circumstances. Well done.
William

On Wed, 13 Oct 2021 at 08:24, 'JR' via croydonastro <croydo...@googlegroups.com> wrote:
Hi John
I hope all is well with you.

Your image is superb.  If I could get close to that I would be more than happy.

Thanks for your kind comments as well.  You have summed it up well.  OSC and limited data.  I have weighed up the monochrome route several times but the reality is that the number of nights I could use it seem to increasingly limited by weather and the possibility of collecting data on several sessions seems to be decreasing.

With other things going on and the weather, by the time another clear night comes round the object might well no longer be visible behind the many trees we have, the house etc.  I aim for the best I can do in the circumstances and doing better with experience.
all the best
James

On Tue, 12 Oct 2021 at 16:26, John Mills <ejm...@millseyspages.com> wrote:
Hi James,
That's a very good image using a one shot camera and more so with the short exposure times you were using. I can't remember if I posted my image of the Tulip nebula (SH2-101) taken a few years ago using Ian King's remote 10" RTC in Nerpio, Spain? If not, it was this one.

This was taken over several nights using a QSI camera fitted with Ha, OIII and SII filters. So quite a few hours worth of 600s subs through those filters. It was quite a difficult object to process I recall and done using Photoshop CS2 - the free to download version ;-)

ATB John

On Mon, 11 Oct 2021 at 09:09, <tcos...@gmail.com> wrote:
Hi James
That's a definite improvement and reducing the stars has helped to make the nebula more visible. My wife was rather derogatory about me removing stars in my last image, but it is necessary in these narrowband nebula images because the stars can overwhelm the subject i.e. the nebula, if they are not properly controlled. It can be a very time consuming exercise needing quite  a lot of experimentation and the resultant artefacts have to be dealt with too, but worth it in the end.
KR
Tim

On Sun, 10 Oct 2021 at 21:31, trevsie7 <trevs...@gmail.com> wrote:
James, that's a vast improvement. You have extracted a lot more detail this time

[JR]

William

Inevitably, star removal needs something like Photoshop.  A popular diy method is to remove stars by selecting a colour.  I haven't ever tried it but you could use it to select say blue stars and redder ones separately.  This would work I expect using GIMP, the freeware PS equivalent.

This won't give you the stars as a separate layer.  This is useful to have.  You can remove the stars and process the object and background without affecting star colours or increasing their size.  This can happen with stretching if highlights are brought out.  The star layer can also be processed on its own, eg saturation to bring out colour, and then be recombined with the starless layer.

Making star layers in photoshop requires use of masks.  I have come across youtube videos that will walk you through it.  Maybe GIMP could do this too.

On the other hand, even good cooks buy ready made puff pastry rather than make it themselves.  Guaranteed to rise!  The proprietary softwares can be quite expensive but I find PS action sets work very well and can be excellent value for money.  In particular, Annie's Actions, at a cost of $20, does star removal and star layer, and they include a wide range of other useful enhancements and automated image RGB and narrowband composition.  You do of course need Photoshop, though the elderly open access CS2 version may be still available and in my experience does most things that later versions do, if not so conveniently.  It needs a key to activate but that is also on line with a bit of determined searching.  

Annie's actions also seem to cope well with evolving hardware, unlike say the Carboni Actions and Gradient Xterminator which require a new full price purchase if you move from 32 to 64 bit computer processors.

A layered gif is a great idea, showing with and without stars and perhaps the ability to reduce progressively the number of stars in the star layer to taste.  Beyond me though.

regards

James

Sent from my iPad

On 21 Oct 2021, at 13:34, William Bottaci <w.bo...@gmail.com> wrote:



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