Starless NGC3372

[Bassnut]

Hi Guys

I thought Id give the starless thang another crack ;).

Starless NGC3372 Keyhole Nebula (http://fredsastro.googlepages.com/)
Ha RGB : Ha 12hrs, 3 nm 10min subs bin1: RGB 45mins each, 5 min subs bin2
Taken on a Meade 12" LX200R OTA, G11, ST10XME, at f6.7

Not worrying about stars allowed far more pushing to bring out surrounding detail I havent been able to extract before. Although the keyhole itself aint that flash, the 3nm Ha nicely did the trick generally.

Enjoy :P
Cheers

[AlexN]

Awesome narrow field Fred! such intricate detail showing throughout the image.. :)

well done!

[leon]

Actually Fred that dosen't lot half bad with out the stars, it seems like a fine image to me, nice work.

Leon

[lesbehrens]

great:thumbsup:

[mick pinner]

may l ask how you achieve this. no stars l mean.

[renormalised]

Nice image, Fred:)

Now that you've go the max out of the neb', I wonder what it would look like with the stars put back in, after sharpening them up to the max??

[atalas]

Amazing detail Fred ! another APOD?maybe.

[Bassnut]

Thanks Alex, Leon, Les and Mick

Dropping the stars was a long story that became a short one.

I took some 5hrs with a continuum filter, its a few Nm off the Ha band so you only get stars (no neb).

I tried to use it to subtract stars, but it doesnt work very well, I cant find anywhere on the net how to use it. As its 3nm, you have to push it like hell, and it still doesnt show as many stars as a colour filter. I gave up.

So, I colour select the stars on a colour sub (nice and big and lots of them), deselect the neb caught in the selection, lasso odd remaining stars painfully time consuming, modify>expand by 6, feather by 4 (then save the selection) and then hammer the selected stars to oblivion with the minimise filter (sometimes in 2 stages, modify>contact by 3 and minimise again).

Heal out giant stars and the artifacts they left.

Sharpening and hi pass masks then become a doddle to use, because theres no star artifacts to worry about. I pulled out more surrounding detail than some who really know what they are doing :P.

I thought to myself, this is cheating, but I dont pretend to be accurate, and then, well, most of the stars in any image show forground stars that are not in the subject, so perhaps this is a more accurrate view if you were standing in front of it :D.

[Bassnut]

Umm, hadnt thought of that, seems obvious, ill give it a go later :thumbsup:.

Louie, nup, I dont think its up to scratch or different enough. The detail in the keyhole is a bit ordinary. The Meades resolution cant quite go the last mile, some examples ive seen elsewhere are just jaw dropping.

[AlexN]

All that means is that you need to do it again with the 10" RC + ST8XME Fred... :) resolution should be better then! :)

I must ask, the stars through a 3nm Ha filter must be TINY! did you do the star removal purely for the stars in the RGB images? or do you prefer the look minus the foreground stars?

I might add that I aspire to getting images like yours from my SCT... (I aspire to have clear skies first! :))

[strongmanmike]

:rofl::rofl::rofl::rofl::rofl:

Oh dear................over half a a day of exposure ..for that?

In-ter-es-ting I guess..?

Maybe another APOD? :P

Mike
luv ya Fred

[Peter Ward]

Interesting. I rather like the "painting look" to the data

Cheers
Peter

[Bassnut]

Alex

The RC has an ST10 now, and same cam angle, mmm could combine subs...

Yes, the Ha stars were tiny, and easy to get rid of, the RGB was harder.

I just did starless for fun, something different, not that I prefer iether way, Ill drop them in again and see how it looks.

Mike, Peter. Not sure if you lot are having a lend or what. No, its not APOD material, and no, its not "painted" at all. Selective masked sharpening and curves thats all (apart from the min filter on the stars).:whistle:

[Peter Ward]

Nah...I was not being funny. I really do like the "look" of the processed data. (..hey Fred...thought you'd know by now I'm not PC...even though it gets me into some interesting debates at times :) )

[AlexN]

Fred - I'd get plenty of Ha data from the RC+ST10 to use as a lum and keep the current colour data.... Although after undertaking 12hrs of Ha data already, it might be a real pain doing it all again... Could make all the difference though?

[strongmanmike]

Well I "was" being funny :lol: :rofl:

To me the thought of spending over half a day on such a bright object would demand..?...well?...something more natural and less processed as the first offering. This might rank as a quirky repro but as the main result...? Hmm? :shrug:

Quite interesting none the less Fred and don't take me too seriously, you know I love playin witch ya :whistle:

No rules in imaging really

Mike

[multiweb]

Very nice Fred. I Love this starless stuff. That's a beautiful picture. Looks like a painting. Lights and shadows are great. Top work. :thumbsup:

[Bassnut]

Thanks Marc, appreciate it, something different at least :D.

Alex. Yes, logically lum or Ha would be the go on the RC, much better res, but its "expensive" for me cause megadata on G15 stops paying customers!, ahhhh, the quandry :shrug:.

Peter n Mike, yeah, I deserve a rib, and well, like it hehe, I love a good stir up ;). And, youve been a bit quiet on that front Peter, whats up?, could I start you up perhaps with a mention on what a heap of junk the RCOS TCC is?, ive been through several over the last few months on G15, the focusing part craps out with blinding regularity, no fix in sight from RCOS so I finally have to resort to a Robofocus retrofit (noticed they now offer this as an option on there web site now?, ask em why :lol:)

Mike. 5 hrs a go is the same effort as 1 hr (set and go, collect result next morning), so why not?. Yes it looks like a repro, but I was hoping for a better result with the ST10 and 3nm Ha (1st was ST8 and 15nm Ha). Also, my view is so restricted, its about the only thing I can do right now (dim stuff is difficult with 3nm Ha, 20min subs at least).

[strongmanmike]

Fair'nuf :)

"view is so restricted" huh? Ooooh, what am I hearing? going to "widen" your horizons so to speak are we? ;)

Set and go, reults in the morning huh?...lucky (lazy) bugger! :sadeyes:

Mike :)

[Bassnut]

ooi sport, "wide", as in shorter FL???, wash your mouth out with soap, punk :eyepop:. Sheesh, me and a poky refractor, not in your lifetime :whistle::D .

[renormalised]

Pity you've got a 12" LX200R, Fred. If you had a normal GPS or classic, or even the ACF, you could've gotten a hyperstar lens system and converted a 10" or 14" f/10 into a 10" or 14" f/1.8!!!!...even if you had to retrofit it with a conversion kit, there'd be your fast widefield system:)

They're looking to make a hyperstar for the Meade 8" and 12" models soon.

[AlexN]

shorter FL? Nah mate... wack a 2x barlow in it!! :)

I want to see a close up pic of the fickle finger beside the keyhole ! :)

[AlexN]

renormalised - saying something like that to Fred is going the right way for a smacked bottom! :) Short focal lenghts are for sissies (and learner imagers like myself..) I'm getting there though.. Next image I do will be at 1760mm... Hoping to go 2800mm by the end of this year. :)

[renormalised]

You notice how most of the professional imagers (i.e. astronomers) take pics with instruments with FL's as low as f/2. All the shots from the prime focus cages are about that long in FL. Shots at short FL's are probably harder as you need excellent focus (and look at how hard that can be to get)....long FL's are either for peeps who like imaging planets and such, or for people with the patience of Job, who like to sit around for hours trying to get enough photons just to see anything!!!:eyepop::P:D

Don't me wrong...I like both. They both require practice and have their good and bad points:)

[renormalised]

Like long FL...get them to make a x9 or x10 Powermate...then you'll have heaps of focal length, and the FoV equivalent of a single photon!!!:eyepop::P:D

[Bassnut]

Renormailsed (sheesh mate, whats your real name, I forget......). Yeah, despite my adversion to the sissy (I like that, so appropriate) FL, the hyperstar conversion is attractive, F1.8 with an 85% QE cam and megadata, insane, would be very interesting :thumbsup:. The ST10 would provide rather a large obstruction tho :P.

Alex, actually tried a 5* Power mate on the finger, a blurry mess (might post it, for a laugh), Id need to get the PME back home to try that again.

Go for it Alex, long FL is a buzz, cleans the soul. Super sharp WW stuff is for sissies, bang on there, 2800mm?, right on, I await with expectation :D.

[gregbradley]

Hi Fred,

I like it. I've done a few of these starless images myself and they are an interesting effect and serve to highlight the nebula.

The 3nm Ha really pulls out some subtle folds in the gas cloud that don't normally show.

Greg.

[AlexN]

Fred : I've done a couple of shots with the C11 @ 6.3 1764mm F/L and even though they are much harder to capture, the detail in the images in extreme! I love it to death... Just waiting on my phone call from Astrophysics for my AP1200, Then I'll be removing the focal reducer and going for broke with C11 F/10 :) I too await! :) Might be a year or so, but when it happens it should be very exciting! :)

I do like my wide field sissy shots, as they are teaching me a lot about processing and the ins and outs of my system, but they just lack impact for me.. Long FL + Small Sensor = Awesome! :)

[Bassnut]

Oh yeah, the AP1200 is a killer, thats the key, serious match for the PME, and would make the C11 shine, nice pick Alex, welcome to the zoom-in club :thumbsup:.

Greg. Yes, 3nm is a bietch on sub exposure length, but in a world of same-as, it makes the effort worth it IMO. Come to think of it, 3nm Ha on the new Tak, would render insane detail, especially at your dark site, gaud, please try that :scared:.

[gregbradley]

I was thinking of that. Astrodon make a 3nm Ha but its US$1000 for a 50mm square. But then I don't like swapping filters between cameras.

I just found out to my amazement that the reason I was getting dim "Ha" from my Microline was not because it isn't sensitive to Ha - it is.
It was because I had mistakenly installed the S11 filter thinking it was the Ha (both red but S11 darker red -grrrr).

Greg.

[strongmanmike]

...ok, done with an almost wide angled 1140mm FL and just a few 10min exposures :whistle::

http://www.pbase.com/strongmanmike2002/image/108471681/original

and just to prove the point - even closer:

http://www.pbase.com/strongmanmike2002/image/96425889/original


Not just FL that counts but good quality unobstructed optics with a mono chip cam help too :P long live the refractor :lol:

Incidentally, this data was taken with Eta still pretty low (< 40deg) in the sky early last year, must try again this year when it is nearer the meridian and hopefully in good seeing :D

Mike

[atalas]

Oh come on big Mike ! you got to be scratching you head at some of the APODS...surely.
I'm sure the was a time there you were thinking only Sbig cameras could score and APOD eh? :lol:

[Ric]

Very nice work Fred, I quite enjoy these starless images.

Cheers

[AlexN]

Mate, not bad... However a 6" AP refractor is not a sissy toy :P

Oh, and imagine what that would look like if that was not a crop, but full frame of the KAF0900 sensor, or your KAI11002...? Obviously the seeing require to capture an image like that would greatly exceed what we could ever expect on earth.. BUT, IF we could, longer focal length would produce a better image...

Also - something like the C11 would get beaten by a 6" triplet APO, but exchange the C11 for a 12.5~17" RC or CDK and you're looking at a big big contest for the better image :) :) I personally look forward to Greg Bradley doing a direct comparision between his TEC180FL and TAK BRC-250...:) My money says the big mirror wins :) (only because I want the mirror to win! :))

[strongmanmike]

Yes sometimes they present some pretty ordinary images and of the same objects over and over again but most of the time they are real crakers!



Me?? neeeever :whistle:

[strongmanmike]

Quite right and I feel very lucky to have one, truly.



Ah yes but those sort of conditions are pretty rare and a longer FL instument will show little improvement over this image untill the aperture significantly increases and really only then in good seeing. The added advantage of what I call the "sweet spot" in imaging focal length (ie about 1200mm FL) is that with say a 35mm size chip you can also fit a lot more in the 1.8 deg wide FOV then make several images from one.



Yes looking forward to that too...I already know the winner though ;)

Mike

[Terry B]

I like the longer focal length imaging but then I like to see images of galaxies and PNs (and most are pretty small). Not much point taking widefield images when the subject only fits on 10 pixels.
You can always take the same image throught the slower scope and bin it for exactly the same brightness as taking it through the shorter focal length scope.

[renormalised]

That's true....you're only going to use those short FL's on large, extended objects and others that can take it. Most PN's would just be starlike points at f/2. That's why the SCT's f/8 is a compromise between fast optics/widefields and good detail on small objects using slower FL's. Trying to be best of both worlds.

However, you can have too much of a good thing with FL...go too long and you end up with either a blur or so little FoV you're virtually straining photons through the front of your scope!!:P