Day of the Triffids - M20 in RGB, HaRGB & HaO3S2+RGB
Hey folks,
Long post ahead...
We had an unusually decent run of clear nights here in Melbourne last week, so I've managed to collect about 18 hrs data on this imaging favourite, good old M20, to take on the Triffid wars!
It's also been exactly six years to the day that I first imaged this thing - in fact it was my very first dark site experience and I remember well shooting at 3:30am in freezing cold & barely knowing what I was doing!
We all started somewhere, but I remember being so very happy with this at the time
I've produced three new images of the subject.
Straight RGB paying homage to David Malin's Benchmark AAO image.
Came out pretty well considering it's from my light polluted suburban location. Had to use a seperate blue LUM layer - which is a technique I made up on the spot that seems to have worked ok!
Can't compare my 10" to the AAO 3.9m telescope - but advances in digital imaging have certainly come a long way since Dr. Malin took his version - which helps us little guys out a bit now. 4 hrs RGB - 40x120 sec ea.
The second is a Ha RGB blend - inspired by Steven Mohr's wonderful image.
Steven's was taken from a remote dark site, and has at least twice the data - so his version seems to have retained a lot more of the blue reflection nebulosity.
Interesting though to see the detail present that the Ha filter reveals, at the cost of the reflection nebulosity present. Really challenging to balance the two and I think Steven has done a remarkable job on his version.
Same data set as above but with an additional 4hrs Ha - 26x600 secs 3nm
Finally, I present for your consideration this hybrid - HaO3S2+RGB NB version referencing Martin Pugh's APOD image.
The gauntlet was thrown down by big Mike and Suavi to produce an aesthetically pleasing hybrid image. One that balances all three NB lines with the traditional RGB.
Hopefully this has gone some way to measuring up to the standards set by the aforementioned illustrious imaging predecessors. - Anyway, I've given it my best shot
Same data set as the HaRGB above but with an additional 4hrs ea of O3 & S2 - 24 x 600secs 3nm
Big thanks to Suavi & Mike for inspiration and Greg, Peter and others for their feedback when I took on this daunting project.
It's certainly pushed me to use everything I have learned about astro image making from all contributors here on IIS.
Feedback welcome
Last edited by Andy01; 08-07-2019 at 04:49 PM.
Reason: typo
Great to hear you had a run of good astro weather. The images are splendid - and what an improvement on your first attempt at the Trifid! Let the thrill of noticing cosmic messengers (photons) continue as long as possible for all of us.
In pure RGB, I really like how you presented blue reflection nebulosity - what a gentle and beautiful sight. The versions that include narrowband nicely highlight interesting structures within the Trifid. I really cannot pick just one - all versions offer different interesting views of the Trifid and I like them all.
Really well done Andy - I hope weather gods will allow me to present something worthwhile in the not too distant future.
I really like the RGB, lovely framing with NGC6531 in frame as well....plus it's nice to see some well resolved narrow field work....sure it takes effort, but rewarding images like this are hard to go past.
Epic work Andy.
Very impressive collection.
I’ll attempt to start the war on the other front(beginners section)
Hehehhehe
Anth
Cheers - Good on you Anth - keep up the good fight!
Quote:
Originally Posted by Slawomir
Hi Andy,
Great to hear you had a run of good astro weather. The images are splendid - and what an improvement on your first attempt at the Trifid! Let the thrill of noticing cosmic messengers (photons) continue as long as possible for all of us.
In pure RGB, I really like how you presented blue reflection nebulosity - what a gentle and beautiful sight. The versions that include narrowband nicely highlight interesting structures within the Trifid. I really cannot pick just one - all versions offer different interesting views of the Trifid and I like them all.
Really well done Andy - I hope weather gods will allow me to present something worthwhile in the not too distant future.
Thanks very much Suavi - I'm 100% confident you'll knock it out of the park
Quote:
Originally Posted by kosborn
Great work Andy. Clearly, the straight RGB is the best.
Kevin
Lol - Goodonya Kevin - Seems that the Astrobin gods agree with you, it's a TP there already! Who would have thought broadband from the 'burbs would work?
Quote:
Originally Posted by Peter Ward
Cracker of a triffid
I really like the RGB, lovely framing with NGC6531 in frame as well....plus it's nice to see some well resolved narrow field work....sure it takes effort, but rewarding images like this are hard to go past.
Cheers Peter, when one takes on a classic DSO such as this, it's a real challenge to hit the sweet spot when so many have done so well before!
Thanks for your encouragement and nice feedback
Quote:
Originally Posted by Nikolas
Wonderful images, I'd love to know your workflow if it isn't pixinsight as I have no intention of using it
Thanks Nik - I'm not a PI user so I'll briefly outline my workflow for you.
Capture: Nebulosity/Dithered/PHD2/OAG
Alignment/Calibration/Stacking: Astropixel processor
Post Processing/Colourization: PSCC2019 using Marco's Method
Topaz Labs N/R
I am hard pressed to say which I like most, either the RGB which has that lovely detail in the reflection areas, or the fantastic crispness the HA-RGB gives in the core of the nebula.
Something I am going to have to have a proper crack at with the OSC, I will have to go widefield I think and bring the Lagoon in to it. The IR cut I think benefits my camera a lot and I can see the same issues in mine with the SCT as I was seeing with the 72mm refractor, just not as badly. I think I will abandon imaging with the SCT until budget allows for a UV-IR cut SCT thread filter. Hopefully I will get my bits back for the filter to go with the 72mm this week.
Very very good Andy! I do like how you’ve done the three different versions and I particularly like the plain RGB image, especially from suburbia. The narrowband image is a wealth of contrast and subtle details. I love the colours in the straight RGB and the fine renditions in the HaRGB.
I do however have one criticism (not so much for the narrowband) and that’s that the noise reduction is a bit too aggressive. You used the Topaz one I believe? I find it works better for daylight than astro, I’ve tried it and decided against it because of what it does to the separation between background and stars.
Viewed at a medium view the stars relative to the background lack the fall off which gives them a harsh and unnatural fall of; its a consequence of all heavy noise reduction. Ironically this isn’t noticeable in the full narrowband image and is strongest in the RGB.
It possibly doesn’t bother a lot of people but it gives a similar view to times when I’ve attempted to blend in Ha and OIII to RGB using a Max() function in PI the wrong way. The background becomes stronger relative to the bottom of the PSF and it doesn’t look right to me
Lovely images Andy. The pedant in me however, needs to mention that the name of M20 is the Trifid Nebula. Trifid with only one f indicates that it is divided in 3 parts rather than Triffid (nasty fictional plants), the name predated the novel.
Nice work Andy, that's the way to do it, produce several combinations to suit all tastes although this way highlights different aspects in the data too. Overall, each of the three versions are kinda nice in their own way (err?..except of course the Narrowband ), for me I guess the HaRGB version most appears the way I think the Trifid should look but I recon you will get as many opinions and tastes, as there are ways of combining the data
I am hard pressed to say which I like most, either the RGB which has that lovely detail in the reflection areas, or the fantastic crispness the HA-RGB gives in the core of the nebula.
Yep, maybe I should run a poll to see which is the most popular version, lol
Quote:
Originally Posted by Atmos
Very very good Andy! I do like how you’ve done the three different versions and I particularly like the plain RGB image, especially from suburbia. The narrowband image is a wealth of contrast and subtle details. I love the colours in the straight RGB and the fine renditions in the HaRGB.
I do however have one criticism (not so much for the narrowband) and that’s that the noise reduction is a bit too aggressive. You used the Topaz one I believe? The background becomes stronger relative to the bottom of the PSF and it doesn’t look right to me
Thanks Col, but I'm delighted with Topaz at present. It uniquely uses ai machine learning to both sharpen the image and/or reduce noise. I find that when shooting under LP it really, really helps clean up the image. Of course, yet more data would help too
Quote:
Originally Posted by barx1963
Lovely images Andy. The pedant in me however, needs to mention that the name of M20 is the Trifid Nebula. Trifid with only one f indicates that it is divided in 3 parts rather than Triffid (nasty fictional plants), the name predated the novel.
Cracking images nonetheless
Malcolm
I'm a huge fan of TDOTT book & movies, so was referencing the anniversary of my first version from 6 years ago with the invasion of this image trio.
Quote:
Originally Posted by Nikolas
Thanks Andy, super useful!!
Cheers and hoping I can equal your work one day
Cheers Nikolas, As you saw from my first version 6 years ago, we all improve with time - somewhat like a nice red wine perhaps!
Quote:
Originally Posted by strongmanmike
Nice work Andy, that's the way to do it, produce several combinations to suit all tastes although this way highlights different aspects in the data too. Overall, each of the three versions are kinda nice in their own way (err?..except of course the Narrowband ), for me I guess the HaRGB version most appears the way I think the Trifid should look but I recon you will get as many opinions and tastes, as there are ways of combining the data
The data looks to be of good quality though
Mike
PS the NB version isn't that bad
Cheers Mike - 'twas a fun & challenging journey to produce these. Yes, a bit like politics, we've all got our own preferred tastes - interesting so see the differences that the various filters can make. The standalone S2 masterfile (attached) is also quite pretty by itself.
So far it appears that the RGB version is the most popular
Quote:
Originally Posted by Bart
The RGB for me, Andy, although you should get an "A" for effort on every one of them!
The NB+RGB version beautifully shows the Herbig-Haro jet. In the straight RGB version, it's barely visible; yet the NB+RGB shows the reflection nebulosity, and the bright cluster toward top right sparkles. The two versions are complementary.
The NB+RGB version beautifully shows the Herbig-Haro jet. In the straight RGB version, it's barely visible; yet the NB+RGB shows the reflection nebulosity, and the bright cluster toward top right sparkles. The two versions are complementary.
Bravo.
Cheers M&T - yes it's interesting to see what structures are revealed by NB but hidden in broadband.
Hopefully this exercise will be useful for those planning to image various emission/reflection DSO's in future. It's certainly given me much food for thought anyway
Quote:
Originally Posted by John K
Great work Andy,
There is a lot of work there and these are some great images!!
Thank for sharing.
John K.
Thanks John - yes it took a while to achieve a pleasing aesthetic balance between the various filters - but I learned/made up a few new techniques on the way so it was very worthwhile.
Really nice work, Andy. I'm in the crowd that finds the RGB version most appealing. Would you mind elaborating on the use of B as luminance? Are you saying that you added a B luminance in addition to the normal LRGB, or is your image BRGB? Thanks
), for me I guess the HaRGB version most appears the way I think the Trifid should look but I recon you will get as many opinions and tastes, as there are ways of combining the data 
