StarTools

Hi all,

having seen all this fine flames and horses that Ron and Freddy posted, I would like share my version. Maybe it's of interest, as this was taken with my newtonian in opposite to Ron's and Freddy's high-quality refractor scopes.

After 1.5 hours I noticed, that camera was out of focus and so again only 50 minutes of light It seems that I'm the master of limited integration time - or maybe more some kind of Don Quixote?


- 200/1000 GSO Newton / SkyWatcher EQ-5
- Baader MPCC
- UV/IR cut
- EOS 2000Da, APT
- 50/200 Guide Scope, ASI 120 MC, PHD2

- 50 x 60s @ ISO 800
- flats, bias

The night was unusual clear for my location and therefore it was easy to get rid of the weak remaining gradient.

Data is weak and so I decided to bin down to 33%. This is the first time I used the "33% median" preset of ST 9. I ran HDR two times with different context sizes - 25 pixels to tame Alnitak (tame highlights set to 1.25) and second time context size 10 px to bring out the small structures in the flame (tame highlights set to 1). I'm still struggling with SV Decon in ST 9 - depending on the workflow there are not much usable starfishies. But nevertheless SVDecon had a noticeable impact on the stars. I did not use the "Shrink" and "Superstructure" modules, just NR with detail size boosted up to 15px. No idea, if this is the intended use, but I think it worked quite well for me?!

Comments welcome.

Best regards, Dietmar.

Impressive!

Lots of detail for only 50 minutes. The Flame looks good, as does that little reflective area below the horsey. Medium stars might have a little Pepsi action going on in the diffraction?

Mostly I like Alnitak. Sharp, and being given its due honor of dominating the scene with power, yet not in an obnoxious way.

I'm pretty sure if I try it I'll have split spikes, since they extend so far out.

Between your post and Ron's, I've been trying to look up proper color for Alnitak, and I can't say I've come up with anything certain.

The extent that any color is certain, of course. But, I see a couple B-V charts out there on the internet, and they don't seem to exactly match. Should the sun be considered white, or yellow? Is an A star white? And then Alnitak itself, a powerful blue O supergiant, has a B-V which seems to put it in the light cyan range, yet a U-B value that would be a very solid bright blue, though not headed over towards violet.

Who knows?

Maybe I'll try an hour myself (though from Bortle 8) and see what color it ends up as.

The red nebulae is a bit dim, off course due to the lack of integration time. But the flame is allready great and detailed.
But mostly Alnitak is a pearl! Really nice to see how it is transformed to a sparkling strong star...

All by it a great image. Needs a bit of integration time but other then that ..it is great.imo

Thanks, Freddy

fmeireso wrote: ↑Sun Feb 19, 2023 7:11 pm The red nebulae is a bit dim, off course due to the lack of integration time.

Yes, that's true. But I was glad to get this outcome with only 50 minutes of light.

BTW: I was surprised to see all the faint dark structures in your image of IC 434. There may be many bad weather days in Belgium, but when it is clear, you seem to have a pretty dark sky ... ?!

Best regards, Dietmar.

Hi Mike, thank you.

Mike in Rancho wrote: ↑Sun Feb 19, 2023 6:18 pm Medium stars might have a little Pepsi action going on in the diffraction?

You're right, I've already noticed that. This is new for me. I switched from DSS to ASTAP, and it's never been a problem when using DSS. The RGB alignment seems to work pretty well with DSS. Most of the images I have stacked with ASTAP were taken at high declination angle, so there was probably only weak atmospheric diffraction. But Orion is at low declination for me, and that might be why this is showing up now I'll check it out.

Mike in Rancho wrote: ↑Sun Feb 19, 2023 6:18 pm I'm pretty sure if I try it I'll have split spikes, since they extend so far out.

Yes, I too still have some problems with the collimation. When it is minimally out of focus, one of the spikes gets split for me as well

Regarding colour calibration I have to admit, I'm feeling pretty lazy when I see all the sophisticated things you are doing there. Usually, I do star sampling as a starting point and then I simply push it to taste

Mike in Rancho wrote: ↑Sun Feb 19, 2023 6:18 pm Maybe I'll try an hour myself (though from Bortle 8) and see what color it ends up as.

At least you could try to take a crop containing only the flame and Alnitak. I did that some years ago with very basic knowledge and rig, but it looks quite nice. Are you sure, you have a Bortle 8 sky? Of course, that's a great urban agglomeration you are living in but having seen your M 78 I nearly can't believe that's Bortle 8. For my location, a light pollution map says Bortle 5 and my M 78 simply was a ridiculous flop

Best regards, Dietmar.

Hmm, interesting Dietmar. What time and filters did you get on M78? And which scope (f/5?) and coma corrector did you use for it? At f/3.8 I doubt I'm that much faster, and of course much more LP will wash that out and probably put me behind.

I'll have to go look but it's likely M78 was another of my "5 hour specials." Two nights seems to have been all I can manage lately.

Have you linked your stacks at all? We could take a look-see at what is there.

Some of the LP maps say I'm a B7, but are taken from data that's probably 20 years old. I've used ASTAP on a dark spot of sky and that put me into the low B8 range. Of course, anywhere away from that spot (for me, straight up and perhaps slightly north) gets progressively brighter, and then there are LP domes all over the place, many of which converge. When I grab things right off the horizon it's probably B11.

I did like ASTAP better than DSS for multi filter/multi night stacking, since you can just throw everything in and let it run, but I turn off the final composing where it will create an RGB file for you, since I do that compositing in ST. But, unlike DSS, you can't pick a reference or stack all to one reference, and what it does is register the separate filters afterwards. Or you run alignment on them, actually. Which Ivo has told us is suboptimal, and it is.

With WBPP I am either not using highlight repair, or if I do it is at a lower pixel value, in most all cases.

I really do need to take some test shots of Alnitak or other very bright stars, as I'm almost positive I am going to have reflection and/or flare issues. So that's something I'll need to figure out a way to remedy.

decay wrote: ↑Mon Feb 20, 2023 5:59 pm
BTW: I was surprised to see all the faint dark structures in your image of IC 434. There may be many bad weather days in Belgium, but when it is clear, you seem to have a pretty dark sky ... ?!

Best regards, Dietmar.

Dietmar,

Not really clear skies here, and at the time IC 434 sat above southeast, lightpolluted by an industrial zone near Ghent. Miles away but still highly interfering.
But The horsehead is a bright region and well the lights go out here on midnight wich surely helped . This is highly uncommon but a benefit.
And well the one night is not the other, some are clear but often they a bit hazy. Can't really remember when i shot it what really the quality was..

CS
Freddy

Mike in Rancho wrote: ↑Mon Feb 20, 2023 7:38 pm Hmm, interesting Dietmar. What time and filters did you get on M78? And which scope (f/5?) and coma corrector did you use for it?

I only have my 8" f/5 newtonian, no other scope, Mike. UV/IR cut filter on my EOS 2000Da with Baader MPCC. About 90 x 60s at ISO 800. But it could be, that it got a bit hazy while imaging. And this might be the reason for the visible gradient in the stacked image. Nevertheless it was a bit disappointing after having seen your fine M78 before.


Regarding LP: I didn't spend much time on this topic until now, because I have to take my location here at home like it is. I will not go out with my scope, that simply takes to much time. But of course, it's interesting to compare different location and their outcomes.
I found an interesting post explaining the Bortle scale and what's the problem with light pollution maps. Unfortunately in German, but if you are interested, you could try to use the Google translator on it. There's a lot of redundancy in it, but this guy has some good points.

https://sternenhimmel-fotografieren.de/ ... tle-skala/

On https://www.lightpollutionmap.info I looked up your and my location. It says SQM 18.49 mag./arc sec2 / Bortle 7 (Alta Loma) and 20.33 mag./arc sec2 / Bortle 5 for my location. Really, I don't know Having a clear night, I can see M31 - just barely. But M33 - no way! I can't even see it with binoculars. This would be Bortle class 6 or 7 if I understand correctly.

But nevertheless my location should be somehow darker than your spot, I guess. It's fascinating what great pictures you make there!

Best regards, Dietmar.

P.S.: I heard about the snow storm coming up in CA. But that's no problem near LA, I hope?!

That's really, really nice, Dietmar! There's nothing like a good newt image of this. Alnitak with great big diffraction spikes is the iconic presentation.

My approach to color is a lot more like yours than Mike's - except after the fact if Mike says something about B-V values and my colors I might go back to see how an image I had "finished" fits. I think your color balance and mine are quite similar, particular looking at the smaller orange-ish stars. I typically just use Stellarium to get B-V values, and all orangey stars in our versions that I checked clock in about +1.5

Tony Flanders, frequent CN poster and formerly prominent Sky & Telescope staff member, continually rails against maps purporting to provide Bortle values (https://www.cloudynights.com/topic/8567 ... nfo-ratio/. I don't quite get what all the fuss is about, but I don't have an old-timer's attachment to the idea of visually determining the Bortle value on every different night. But one idea he champions that makes sense to me is thinking in terms of the artificial:natural brightness ratio. Those numbers are also given on the lightpollution.info maps. My home is shown as a ratio of 13.4 vs my club's dark site an hour drive away at 0.45. Big difference - too bad I only manage to image from there maybe 7-8 times a year.

Hey Dietmar, your M78 isn't bad at all. Nice detail and colors in there, along with much dark shadow nebula.

I think Bortle is good for what it is - a quick and easy reference to give us an idea of a base darkness level. Any of us playing the game for a while realize that sky brightness is dynamic to direction and altitude, among other things.

20.33 is "only" Bortle 5? Good grief. Anyway, I'd love to see 18.49 some night! ASTAP, the program with so many goodies, usually tells me SQM of 17.6 or so, sometimes higher, if I just give it a good sub plus a dark and a flat. My current best L sub from M81 rates about that, but of course is pretty low. Same with one of my comet subs, though it was a moon night. My M31 from September was taken at about 78° alt, and I get an SQM of 18.13. But M31 covers my FOV pretty well, so I don't know if that hurts accuracy the way Han says a lot of nebulosity can.

ASTAP can also run a pretty interesting test of limiting magnitude, on a sub or a finished stack I believe.

There are a number of possibilities though for diferences, even with your pitch black skies.

• Cooled mono vs DSLR

• 5 hours vs 90 minutes

• 1 hour dedicated to Ha filter - 95% of the pretty red came from NB Accent.

• f/3.8 vs f/5

• 585mm vs 750mm and resultant pixel scale

• Mad skillz

• Latitude, altitude and extinction.

In fact the last one, you're pretty far up there right? 50°+? So, not like Alaska or anything, but still perhaps as far north as lots of Canada where nobody lives.

Speaking of latitude, no snow for me! But it's been close. I'm only at about 1,450 ft elevation, but I could see the snow up the hill a little ways. Brrr. It has been chilly, and a lot of precip the last couple days has fallen as various forms of ice - small hail, sleet, maybe graupel. Will see what happens overnight through Saturday as that's when the bigger storm comes in and all the blizzard warnings go into effect, but that's for over 4,000 ft.