Tarantula narrow band

[kosborn (Kevin)]

Hi all,

My last clear night was about 6 days ago when I collected some narrow band data on the Tarantula. I've spent most of my spare time since trying to process it, attempting to mimic the Hubble palette - I didn't realise it would be so difficult! I clearly need lots more data but this is what I have so far.

I'm not sure of the proper steps with nb imaging, particularly image registration. I registered all the individual frames with each other (is that correct?) before integrating Ha, OIII and SII separately, then doing a linear fit of Ha and OIII to SII, followed by LRGB combination and colour masking in the non-linear stage to tweak the colours. Are there any suggestions on how best to do it? (I'm using Pixinsight).

Thanks, Kevin

[Mickoid (Michael)]

Kevin, you may not have mastered the Hubble Palette yet but you've produced a very nice shot. I like it a lot, a little soft perhaps and maybe that's been caused by focus, seeing conditions or the file compression down to 200kb but basically a great result from your NB experimentation. Keep them coming, we'll love to follow your progress.

[xelasnave]

Kevin I really do like your image.
Most of all I like the "softness" as it lends an effect than makes it seem realistic such that it seems I am actually in a space craft approaching the region.
And so I give it top marks.
I showed the others here and the comments were similar to my feeling " that seems so real" sums it up.
Well done in my view.
Alex

[kosborn (Kevin)]

Thanks, Michael and Alex.

Focus may well be a problem. I was using BackyardEOS with a DSLR previously and focusing was really simple - live view, select a star and fiddle focus until FWHM was minimum. I'm using a trial version of SG Pro at the moment and there doesn't seem to be a similar simple way to get good focus.

With this image I was concentrating so much on colour that I forgot to do any sharpening. Here is the previous (and a detail view) with sharpening. Better or not?

Kevin

[that_guy (Tony)]

SGP does have a similar function to FWHM method of focusing. It's under frame and focusing. Once you select the exposure and continuous shooting, click on the display FWHM button. Also, nice image

[carlstronomy (Carl)]

Really nice image, you have some great data there

So much better than my attempt from last week.....

[Nikolas (Nik)]

That certainly kills my effort, very nice indeed

[PKay (Peter)]

Well done Kevin.

You have captured just about ever colour known

[ChrisV (Chris)]

Great colour balance kevin. Looks like it's back to the drawing board for me !!!

[rcheshire (Rowland)]

Nice work Kevin.

[kosborn (Kevin)]

Thanks all for the encouragement. I'm really enjoying narrowband especially with all the lights in the neighbourhood and the waxing moon.

Originally Posted by PKay

Well done Kevin.

You have captured just about ever colour known

Thanks Peter, but I'm not sure that's necessarily a good thing .

Kevin

[RickS (Rick)]

Hi Kevin,

That's a nice image.

Your process seems quite sound. Registering all the subs to the same reference is perfect and using LinearFit to equalise the three masters is good practice (unless you like pure green images.)

Here's my rough workflow for Hubble NB...

Prep: calibrate, register & stack as you're already doing (hopefully you're tweaking the rejection algorithm and parameters to get best SNR from the data?)

Colour data: Remove stars from a copy of the NB masters (star mask & repeated application of MMT to remove first few layers then CloneStamp clean up.) MLT noise reduction (you can go heavy.) SHO colour combine and apply unlinked HT stretch. ACDNR noise reduction and lots of ColorMask/CurvesTransformation tweaking to get colour as wanted.

Luminance: Use ImageIntegration without rejection to do a noise weighted combination of the NB masters. This is the luminance. MLT noise reduction, HT stretch, dynamic range tweaks (HDRMT, LHE), star reduction if needed, more noise reduction if needed, sharpen if needed (clipped lum mask and MLT bias adjustment)

Final image: LRGBCombination to combine Lum and colour. Final tweaking.

Voila!

Cheers,
Rick.