L-eNhance star colors

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arrowspace90
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L-eNhance star colors

Post by arrowspace90 »

I think the L-eNhance does a nice job of bringing out nebulosity.
But when I process with it, it causes my stars look too blue.
I read a post here from about a year ago, which I have a difficult time following.
This person had the same filter and similarly used an OSC camera. The suggestion for him was to go to the Compose mode, and load his unstretched stack 3 times, once for R/G/&B, having specified LLRGB Mono. Is this right?
So Star Tools accepts those and then you keep that and save it. What format do you save it as?
From that point, I was not sure what to do, or even if I was trying to accomplish something possible. By that I mean, did the original poster have a second set of data in which he swapped out his L-eNance filter for something else? Did he only use his OSC/L-eNhance data?
I really need to see a tutorial of this, or if it can be described in step by step terms.
In the future, I plan to use the newer L-extreme filter which is more of a true duoband and is definitely going to mess with stars. Perhaps the only way to really correct this is to swap filters and get more frames with a broadband filter.
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Re: L-eNhance star colors

Post by admin »

Hi,

I'm admittedly a little confused about your question...

The Optolong L-eNhance filter already is a very strict tri-band filter (Ha, Hb and O-III).
If you use this filter, you are very much not imaging in the visual spectrum, so color response will be very much limited to two hues.
It stands to reason star coloring is completely incorrect if you were somehow expecting visual spectrum coloring.
The image you attached is a nice, text-book HOO-ish bi-color, as can be reasonably be expected from such a filter.

Could you explain how you think that post/suggestion (could you link it for me?) is pertinent to what you are trying to do?

Thank you!
Ivo Jager
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arrowspace90
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Re: L-eNhance star colors

Post by arrowspace90 »

Thanks. I totally get what you're saying.

I wonder if people can layer stars using a different filter on to a set of images that were taken with the nebulosity filter? It sounds like something people who know how to process in depth could do. Like everyone, I guess I would like to have my cake and eat it too (get the L-eNhancement for the nebula and also get the beautiful star colors that I see on my StarTools images that don't use that filter). I know that many people prefer to just shrink away the stars as much as possible and look only at the principal object.
almcl
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Re: L-eNhance star colors

Post by almcl »

Watching this thread with interest as I have started to accumulate some bi-colour nebula images, but (as expected) the star colours are completely washed out.

I have some nice RGB stars and pretty sure that if I knew enough about the layer module (surely one of the great features of StarTools) it would be possible to "drop" the coloured stars into the bi-colour image?
Skywatcher 190MN, ASI 2600 or astro modded Canon 700d, guided by OAG, ASI120, PHD2
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Re: L-eNhance star colors

Post by admin »

would be possible to "drop" the coloured stars into the bi-colour image?
Absolutely!
Simply process the two bi-color and the visual spectrum color stacks separately. Then, once you have processed both, use the Layer module in combination with a star mask to layer in the visual spectrum stars (you can use the Color of Fg mode for this to just inherit the color from the foreground layer).
Ivo Jager
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almcl
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Re: L-eNhance star colors

Post by almcl »

Wow! Thanks so much for that, Ivo.
It worked beyond my wildest expectations:

BEFORE:
the bicolour - No star colours
the bicolour - No star colours
NC3 nights sm.jpg (265.12 KiB) Viewed 1516 times
AFTER:
using the layer mode to add RGB stars
using the layer mode to add RGB stars
NC 3 nights layer blend sm.jpg (274.82 KiB) Viewed 1516 times
Skywatcher 190MN, ASI 2600 or astro modded Canon 700d, guided by OAG, ASI120, PHD2
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Re: L-eNhance star colors

Post by admin »

A fantastic result! :thumbsup:
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ldipenti
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Re: L-eNhance star colors

Post by ldipenti »

Hi Ivo,

I'm interested in the details of this "star color drop in" process as I've recently purchased an Optolong L-extreme filter and want to test it myself, some questions:

* When you say "process both stacks separately" you mean post-process both with StarTools and export them as separate TIFF files?
* If the above answer is "yes", should I then have to register both resulting images (in my case with AstroPixelProcessor) to ensure they'll be aligned when loading them into the Layer module?

Thanks in advance!
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Re: L-eNhance star colors

Post by admin »

ldipenti wrote: Wed Apr 21, 2021 5:47 pm some questions
Hi Lucas,

That's Yes to both questions. The idea is you're using the Layer module to "switch around" the color information between the two images, based on the mask. So you'll definitely want all stars to line up.
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Re: L-eNhance star colors

Post by ldipenti »

Thanks Ivo,

For reference, I've done this with my L-extreme data. I think just adding the narrowband as Luminance and the rest as RGB works pretty well, with the benefit of not having to deal with masks.
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