A bit of everything ... NGC 6559, IC 1274 and IC 4685

marc4darkskies (Marcus) · #1 21-08-2009, 05:53 PM

This image has a bit of everything - dark, emission and reflection nebs and it's embedded within the rich star fields of Sagittarius - a riot of colour!

It's an LLsRGB image 7 hours total. I was initially going gather Ha for this as well but didn't bother as my effective 4 hours of Lum (2.5hrs Lum filter + 1.5hrs Synthetic Lum (Ls = desaturated RGB) revealed enough of it. Also my Ls had tighter stellar profiles than my L (1.5 vs 2.2 pixels FWHM) so combining the two kept my stars tight. Seeing on the 2 nights I imaged was around 2-3 arsecs (I won't mention the completely wasted night where the guide star frequently exploded into a 10 arcsec fuzz ball!

).

I shot this at the native FL of the Tak (F7.3, 1.67 arcsec/pixel) - nice wide, unvignetted flat field (using the 67 flattener). In any case I ended up cropping slightly for composition purposes because in the full frame the subject was off center ... and we can't have that!!

Enough waffle - here 'tis ...

Small:
http://www.pbase.com/gailmarc/image/116319109/large

Large (4MB - use <ctrl-> to zoom out & <ctrl+> to zoom in)
http://www.pbase.com/gailmarc/image/116319109/original

Hope you like it.

Cheers, Marcus

DavidU (Dave) · #2 21-08-2009, 05:57 PM

Nice work there Marcus ! 7hrs on the Tak just works. The #67 seems to do the job
Excellent

Bassnut (Fred) · #3 21-08-2009, 06:04 PM

Very smick Marcus, lots of sharp detail fishing around in the big version, and nice colour too.

RB (Andrew) · #4 21-08-2009, 06:09 PM

Wonderful, absolutely wonderful Marcus !
Gorgeous colours, stars nice and tight, what more can I say.
The full frame almost gave me vertigo.

A beautiful frame indeed.

The TOA 150 with 67 flattener......mmmmmmmm !

multiweb (Marc) · #5 21-08-2009, 06:20 PM

That is superb Marcus. The colours and resolution are unreal. What a shot!

By Ls do you mean you stacked the masters RGB into another Lum in addition of the Lum data you shot?

Lumen Miner (Mitchell) · #6 21-08-2009, 06:42 PM

That's just UNREAL!!!

Lester · #7 21-08-2009, 06:45 PM

Thanks Marcus, that is a beautiful image.

renormalised (Carl) · #8 21-08-2009, 06:50 PM

Only one word....gorgeous!!!!

Another work of scientific art....great shot Marcus

Peter Ward · #9 21-08-2009, 06:54 PM

Think you are on a roll now...do ya?...punk?

Damm...very tidy indeed.

marc4darkskies (Marcus) · #10 21-08-2009, 10:42 PM

Quote:

Originally Posted by DavidU

Nice work there Marcus ! 7hrs on the Tak just works. The #67 seems to do the job
Excellent

Thanks a lot David! The 67 is a sweet piece of glass for sure ... should be too - it wasn't cheap!

Quote:

Originally Posted by Bassnut

Very smick Marcus, lots of sharp detail fishing around in the big version, and nice colour too.

Thanks Fred. Interestingly I didn't apply any sharpen filters to this image except for some "real" unsharp masking to enhance contrast.

Quote:

Originally Posted by RB

Wonderful, absolutely wonderful Marcus !
Gorgeous colours, stars nice and tight, what more can I say.
The full frame almost gave me vertigo.

A beautiful frame indeed.

The TOA 150 with 67 flattener......mmmmmmmm !

Hey thanks Andrew & fellow TOA'er! Yep, I think I need to do more imaging at F7.3 - stars are pinpoints edge to edge!

Quote:

Originally Posted by multiweb

That is superb Marcus. The colours and resolution are unreal. What a shot!

By Ls do you mean you stacked the masters RGB into another Lum in addition of the Lum data you shot?

Cheers Marc. I use Ls by layering in a desaturated version of the combined RGB image in PS. The method really depends on what you want to achieve but in this case, as well as improving S/N, I wanted to rein in the stellar profiles so I did a darken layer at 67% after making sure the nebulosity was normalised with the raw lum.

Quote:

Originally Posted by Lumen Miner

That's just UNREAL!!!

Thanks Mitchell glad you liked it!

Quote:

Originally Posted by Lester

Thanks Marcus, that is a beautiful image.

Cheers, Lester!

Quote:

Originally Posted by renormalised

Only one word....gorgeous!!!!

Another work of scientific art....great shot Marcus

Thanks Carl - if there's one thing I've learned, processing is indeed 80% art and 20% science!

Quote:

Originally Posted by Peter Ward

Think you are on a roll now...do ya?...punk?

Damm...very tidy indeed.

Thankyou master, I am most unworthy of your praise

.

I guess if the clouds are not rolling in as often as usual then, yes, I'm on a roll.

(DANG!!! Shouldn't have said that should I - they probably heard me!

)

Look forward to your first STX shot!

Cheers, Marcus

gregbradley · #11 22-08-2009, 12:47 PM

Another great image Marcus.

Potential winner for next year?

Did you bin the RGB 2x2? I often see lower FWHM numbers for binned RGB compared to
Luminance images at 1x1. So is that when you want to use the desaturated RGB for extra lum to get the
tighter FWHM of the 2x2 RGB? I tried desaturated RGB as extra L but didn't see much of a gain. As you say I suppose it depends on what you are trying to accomplish. I guess if the L is a bit noisy still it would be helpful or for galaxy shots where you you want max data.

Greg.

Paul Haese · #12 22-08-2009, 01:18 PM

Nice Marcus, love the colour and the field of view. Lovely work.

Matty P (Matt) · #13 22-08-2009, 08:56 PM

Just stunning Marcus. I'm still picking my jaw up off the floor.

marc4darkskies (Marcus) · #14 22-08-2009, 10:25 PM

Quote:

Originally Posted by gregbradley

Another great image Marcus.

Potential winner for next year?

Did you bin the RGB 2x2? I often see lower FWHM numbers for binned RGB compared to
Luminance images at 1x1. So is that when you want to use the desaturated RGB for extra lum to get the
tighter FWHM of the 2x2 RGB? I tried desaturated RGB as extra L but didn't see much of a gain. As you say I suppose it depends on what you are trying to accomplish. I guess if the L is a bit noisy still it would be helpful or for galaxy shots where you you want max data.

Greg.

Thanks Greg - I'm pleased with how it turned out and was glad to be able to avoid the hassle of another Ha combine. With I think one exception I always image unbinned. In fact you shouldn't do synthetic lum if you've binned your RGB - you'll sacrifice resolution. The FWHM differential is mainly the result of seeing in this case. I suppose there would be some contribution from the difference between the effective passband of the combined RGB vs the Lum - but probably small. I guess I should quote FWHM in arcsecs to avoid confusion too.

Quote:

Originally Posted by Paul Haese

Nice Marcus, love the colour and the field of view. Lovely work.

Cheers Paul - gad you liked it. Even though I cropped for composition I didn't snip too much off - just some of those pesky stars!

I wanted to highlight how the loop of dark neb frames the subject.

Quote:

Originally Posted by Matty P

Just stunning Marcus. I'm still picking my jaw up off the floor.

Thanks Matty - it's such a vibrant, colourful field with so many facets it'd be hard NOT to make it look good! It's often overlooked though because of it's famous neighbours - I only discovered it recently myself

Cheers, Marcus

Martin Pugh · #15 23-08-2009, 01:00 PM

Hello Marcus

very nice indeed, but it does not compare to your Corona Australis image which I think is just exceptional in every way.

I also enjoyed a good look around your website tonight, and your running photo-commentary of your observatory construction was very good.

Well done mate

cheers
Martin

Alchemy (Clive) · #16 23-08-2009, 05:33 PM

very nice, good color, smooth, nice contrast....

where did the guy in the big hat go? someones pretending to be you !

gregbradley · #17 23-08-2009, 05:49 PM

Thanks for the tip Marcus.

Do you think there is always a gain from 1x1 on the RGB?
Certainly your image in this case is fantastic but do you always see a gain from it or is better to simply do more luminance at 1X1?

I suppose there are 2 schools to this but if one advantage is the ability to add desaturated RGB to the luminance that is something of a dual purpose to your RGB.

I guess in my case recently with such a continual run of poor weather the question is moot anyway.

Greg.

marc4darkskies (Marcus) · #18 23-08-2009, 08:40 PM

Quote:

Originally Posted by Martin Pugh

Hello Marcus

very nice indeed, but it does not compare to your Corona Australis image which I think is just exceptional in every way.

I also enjoyed a good look around your website tonight, and your running photo-commentary of your observatory construction was very good.

Well done mate

cheers
Martin

Hey thanks Martin - appreciate that!! Yeah, it didn't take me long to figure out how much I hated set up & tear down - I had the observatory built after only 5 or 6 sessions I think. So how's the cloud cover in Nebraska?

Quote:

Originally Posted by Alchemy

very nice, good color, smooth, nice contrast....

where did the guy in the big hat go? someones pretending to be you !

Cheers Clive! Hmmm yes, the hat was almost a signature thing wasn't it?

Maybe I'll grow it back!!

Quote:

Originally Posted by gregbradley

Thanks for the tip Marcus.

Do you think there is always a gain from 1x1 on the RGB?
Certainly your image in this case is fantastic but do you always see a gain from it or is better to simply do more luminance at 1X1?

I suppose there are 2 schools to this but if one advantage is the ability to add desaturated RGB to the luminance that is something of a dual purpose to your RGB.

I guess in my case recently with such a continual run of poor weather the question is moot anyway.

Greg.

You'll only get a gain (from Ls) when the RGB is the same or better resolution than the Lum - in which case you always get a noticeable improvement in S/N and the processing benefits that brings. I consider it a bonus when I can do it. I dunno, it's probably just a personal preference thing whether you spend time gathering extra lum or more time gathering RGB in 1x1

. But, I DO like the idea of using the RGB data twice!! ... It feels like you're getting something for nothing

Cheers, Marcus

Peter Ward · #19 23-08-2009, 11:20 PM

Quote:

Originally Posted by marc4darkskies

Look forward to your first STX shot!

Cheers, Marcus

SBIG say no STX until next month and no matching CFW until October

..and will probably run with 3" diameter threads so nothing I have will actually fit. Arrrrgh! What have I done!

I predict clear skies between now and then.....but an unsually wet summer.

marc4darkskies (Marcus) · #20 24-08-2009, 05:19 PM

Quote:

Originally Posted by Peter Ward

SBIG say no STX until next month and no matching CFW until October

..and will probably run with 3" diameter threads so nothing I have will actually fit. Arrrrgh! What have I done!

I predict clear skies between now and then.....but an unsually wet summer.

Bugger ... commiserations! I'd have thought they'd try and make the upgrade path a bit more straightforward.

What about an AO-L - bet you need a new one of those too ... the AO-X??!! I think I'll stick to my trusty STL for a few more years - I hate thinking about adaptor bits and back metal distances anyway.

Cheers Marcus

PS: Thanks in advance for the clear skies - they must be above the rain clouds here at the moment.