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Ngc 6888 in Ha

Singlin

By Singlin
in Imaging - Deep Sky

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Adam J

Adam J

Posted
Posted
10 hours ago, Singlin said:

With OIII added.

 

1stNgc6888.jpg

Got to be honest I think you need to push that OIII data more I am not actually seeing the additional features that I would expect to see in a OIII image of the Cresent in comparison to the Ha. Might be interesting to see the OIII data on its own. 

Adam

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GiorgioF

GiorgioF

Posted
Posted
On 21/08/2019 at 15:50, Singlin said:

Here is a link to my Ha,OII and SII data.

I would be pleased for others to see what they can do so that I can learn from it.

https://www.dropbox.com/s/dv1i2lklxmf87qz/NGC 6888.zip?dl=0

Dear Singlin, I hope you don't mind if I take few minutes to play with your data.

They are really good shots but already in non linear state. This means some result could be better if the job start from the raw data, just stacked.

Anyway, this is my personal interpretation for which I than you for the opportunity.

 

Process was quick and dirty in PI, as said.

Linear fit of the three frames over the O3, combination in HSO. Add the Ha as luminance (thank you Luca for the hint).

Some denoise, a small stars reduction.

Cleaned the red of Ha in PS and adjusted the contrast.

 

Not clean as expected with that data: the shot you got are really good.

Wish you a nice day!

 

HUBBLE_G_clonejpg.jpg

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Spongey

Spongey

Posted
Posted
On 23/08/2019 at 18:01, Singlin said:

Here is a link to my master files

 

https://www.dropbox.com/s/omfochapkz3l7ka/master.7z?dl=0

Hi Simon,

I am a total noob at narrowband; this is literally the first NB image I have attempted to process! 

Thanks so much for posting your data, I am looking to get into narrowband at some point in the future so it is great to have some data to play with until I can capture my own!

Here is my rendition of your crescent nebula :D 

I am interested to know how @GiorgioF has managed to get such clear structure out of the shell, perhaps this comes from adding Ha as a luminance layer?

 

My processing flow was as follows (PixInsight):

Crop of clipped edges

DBE x2 on each channel

Masked MLT noise reduction on each channel 

Histogram transformation to stretch to non-linear on each channel

LHE + curves transform on Ha

Linear fit of OIII and SII to Ha

Pixelmath R = Ha, B = 0.7*OIII + 0.3*SII, G = OIII

Background neutralisation

Curves transform to adjust colour palette

SCNR green

Star reduction using starmask and Morphological Transformation

Some masked curves transformations to work on background + nebulosity separately 

Exported as 16 bit TIFF

 

Imported into Lightroom and adjusted saturation and local contrast adjustments

 

Any feedback is very welcome, as I said this is my first narrowband processing attempt so I'm sure there are plenty of ways to improve!

 

Thanks again for the great data,

Spongey

Singlin Crescent.jpg

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GiorgioF

GiorgioF

Posted
Posted

Each one give his own interpretation in the image elaboration with narrowband, sometimes going out of the "classic" combination. I like to think I'm not doing scientific report with my image. I simply can't.

In answering to the question, what bring out details is usually the luminance.

So, once combined and optimized the NB image, it can be extract the luminance from.

This luminance, if needed with a small "cleaning", is then used to emphasize the NB image adding the (!) Luminance part.

Another way with the H and O files is to combine them in a mix that depend on what you have imaged.

Adding the pure H data as luminance it can not show all the details, especially if the subject is rich in O3. So a mix of them in a percentage that can vary, is a good choice.

I feel comfortable using the SHO script of Pixinsight (can be found in PI forum). It allows more control.

And last, I will never stop to thanks Luca, an Italian guy living in US for teaching me what above.

Another small note is the noise reduction that I use. You can search for the "Jon rista method". Jin is a great photographer and experienced in astrophoto. 

 

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GiorgioF

GiorgioF

Posted
Posted

Great Simon! 

May I suggest you another try?

In ps the "selected color correction" can help to clean and boost the red. The window of the function has a drop down menu. On "Red" you can lower the amount of cyan through the slider near by. With the real time preview you can appreciate the modification. 

 

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GiorgioF

GiorgioF

Posted
Posted
20 hours ago, Singlin said:

Is their a website where I can see different narrowband colour combinations with mixing percentages?

Other than what in PM, you can use the PI script I mentioned (SHO script). You can see it in real time.

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