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ollypenrice

Draco Trio, another one night stand.

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Second light for the Twin TEC140 rig. Starting early we managed 11 hours (5.5 per scope) on the Draco Trio, the spiral being NGC5981. (The rig is O'Donoghue-Milne-Penrice.)

I'm beginning to think that the Luminance scope is out-shooting the colour slightly. I've been using 15 minute L subs on one side and 10 minute RGB on the other (to preserve stellar core colour.) I think some tests with 15 minute colour or a short booster colour run on the 'Lum' side of the rig might give   better results but this is a conversation to have with the other kit owners as well.

The full field looks like this:

1327834835_DRACOTRIOWEBFULL.thumb.jpg.41e93d17baf49f47bc810ce234806d31.jpg

For a 'no hidng place ' crop I ask you to be kind!

1797604744_DRACOTRIOCROP.thumb.jpg.28b5ec3a43c1cb86f9c40b3011213437.jpg

Thoughts most welcome...

Olly

 

 

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Posted (edited)

Excellent image Olly, and congratulations on this new rig to all three "parents".

I know you're an dvocate of the 23/23/23 rule, but imo the background could be a little darker on this one (but viewed on a laptop screen). In the end it's down to personal taste of course.

Edited by wimvb

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Lovely Olly,

I prefer this colour also to the M100 image. I love the smooth background, this really came out very well, as well as the star colours.

Tom.

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20 minutes ago, Tom OD said:

Lovely Olly,

I prefer this colour also to the M100 image. I love the smooth background, this really came out very well, as well as the star colours.

Tom.

The background just looked after itself on this one. I really don't know what was different. See what you make of the raw data.

Olly

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another corker Olly....stunning star colour processed with your usual delicate touch.

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Nice Olly. This is one of my favourite visual targets, and one of the few galaxy groups that look almost as good at the eyepiece as in a picture

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13 hours ago, wimvb said:

Excellent image Olly, and congratulations on this new rig to all three "parents".

I know you're an dvocate of the 23/23/23 rule, but imo the background could be a little darker on this one (but viewed on a laptop screen). In the end it's down to personal taste of course.

I agree. I normally go for 23/23/23 in my widefield images but, with the 460, I can't usually get there. Maybe it's because of a new master dark I'm using but the background has lightened up better on my last two images and I think it does look better brought in a bit. Maybe it's galaxies that look better popping out of the darkness with more contrast.

Olly

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18 minutes ago, ollypenrice said:

I normally go for 23/23/23

Can you enlighten me on this 'rule' please?

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2 minutes ago, mikeyj1 said:

Can you enlighten me on this 'rule' please?

I just wrote this on another thread:

In Ps you can use the Eyedropper set to Colour Sampler to put 4 markers on the background around the image. Go for 3x3 or 5x5 Average with this tool. Then the info palette gives you a readout for the brightness per colour at each sample point. If you aim for about 23/23/23 for starters you'll have got your background right and that's always a good starting point. Resist the temptation to black clip the histogram in order to get rid of a colour gradient. You'll also be getting rid of a lot of precious signal. I always concentrate first on the background sky because it is the foundation of the image and, along with the stars, the hardest part to get right.

If you prefer to be a little darker then that's your call, of course. You may also prefer a slight imbalance, say red one point higher for a warmer look. Some like the blue to be higher but I dislike that myself.

Olly

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I like these kind of images, and this one is a cracker......as usual from this source....especially for a one nighter.  

Just an observation (from my screen) - some of the smaller stars seem very red to me, something I have sometimes noticed  on my own longer FL images.  Is it due to pulling out star colour during processing?  Or they they really this red?

I would be interested to know the field of view (arc minutes) of the top (full field image).

Only one other comment: why stop at only two TEC 140s?  Surely four would enable RLGB to be shot all at once, and imagine the fun for aligning and setting up the mount........

Chris

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Me neither, so thanks for that! 

i just added it to my observing list, and it frames nicely with the sx h9c CCD... :)

 

 

Image-1.jpg

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12 minutes ago, cfpendock said:

I like these kind of images, and this one is a cracker......as usual from this source....especially for a one nighter.  

Just an observation (from my screen) - some of the smaller stars seem very red to me, something I have sometimes noticed  on my own longer FL images.  Is it due to pulling out star colour during processing?  Or they they really this red?

I would be interested to know the field of view (arc minutes) of the top (full field image).

Only one other comment: why stop at only two TEC 140s?  Surely four would enable RLGB to be shot all at once, and imagine the fun for aligning and setting up the mount........

Chris

Thanks and, yes, there are some very red stars, possibly too red. I didn't deliberately make them that way. They may arise from the colour balancing algorithms on targets outside the Milky Way since I often find such stars when imaging what I think of as 'the old sky' - distant galaxies. Since the stars in question lie within the Milky Way, but not in line of sight through the disk, they should surely be less reddened by dust than the stars within the MW? And yet they seem to appear in my images around Virgo etc. I guess I'd better ease them down a bit. Thanks for the observation.

Olly

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1 hour ago, cfpendock said:

Only one other comment: why stop at only two TEC 140s?

That setup is called dragonfly, and is used for hunting veeery faint dwarf galaxies. In its current configuration, I believe it has 48 long fl canon lenses, each about 10 k£.

https://www.dragonflytelescope.org

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2 hours ago, ollypenrice said:

Maybe it's galaxies that look better popping out of the darkness with more contrast.

I think they do. I usually aim for a sky background just shy of 20/20/20 or 0.08 in PixInsight units. The difference is subtle in pixelvalues, but substantial in impact.

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Posted (edited)

So after a few tweaklets we have it thus:

1721500005_DracoTriowebV2.thumb.jpg.87f52a044f2ca4fa7a9b3b6e1ea2d477.jpg

Olly

Plus an 'edit tweaklet' following eagle eyed Dave's comment below!

Edited by ollypenrice
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I think v2 has the edge.

Great framing of this trio on this set up, I always think of it as 'the Galaxy Showroom'.

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Very nice Olly, your "photon hoover" is certainly working very well.  I hesitate to say but there's the odd green star halo here and there, maybe a dose of scnr would fix that.

Dave

 

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Posted (edited)
16 minutes ago, Laurin Dave said:

Very nice Olly, your "photon hoover" is certainly working very well.  I hesitate to say but there's the odd green star halo here and there, maybe a dose of scnr would fix that.

Dave

 

Yes, I missed the ones around the edge. I'll have a look. Cheers. Edit: now fixed (I hope) above.

Olly

Edited by ollypenrice
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2 hours ago, ollypenrice said:

They may arise from the colour balancing algorithms on targets outside the Milky Way since I often find such stars when imaging what I think of as 'the old sky' - distant galaxies. Since the stars in question lie within the Milky Way, but not in line of sight through the disk, they should surely be less reddened by dust than the stars within the MW?

Less reddened perhaps, but could the population of stars be intrinsically redder?

I prefer the tweaked version, better definition in the galaxies I believe. For the cropped version I'd consider rotating it left by about 30 degrees, but without trying it I'm not sure if it would work and whether any interesting fuzzies could be kept in view.

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1 hour ago, Knight of Clear Skies said:

Less reddened perhaps, but could the population of stars be intrinsically redder?

 

I guess it could be. Blue stars proliferate in the spiral arms so, away from them, the bias might well be towards more red ones.

Olly

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2 hours ago, ollypenrice said:

Blue stars proliferate in the spiral arms so, away from them, the bias might well be towards more red ones.

Yes, but I was thinking more about the population of visible red stars. The stars are going to be, on average, older away from the disc, so red giants might be less massive, cooler and redder perhaps? (I don't know what the proportion of visible red giants to dwarfs would be in a typical image, vastly more dwarfs out there but they are introverts.) I might have a look at the DSS to see if I can notice any trends, the colours should be calibrated there.

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30 minutes ago, Knight of Clear Skies said:

Yes, but I was thinking more about the population of visible red stars. The stars are going to be, on average, older away from the disc, so red giants might be less massive, cooler and redder perhaps? (I don't know what the proportion of visible red giants to dwarfs would be in a typical image, vastly more dwarfs out there but they are introverts.) I might have a look at the DSS to see if I can notice any trends, the colours should be calibrated there.

...and the further we stray from the galactic halo the more Population II stars we will find. (I worship at the feet of the mighty Walter Baader but why did he name the populations that way round???:D)

Olly

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Posted (edited)
On 02/04/2019 at 18:49, ollypenrice said:

(I worship at the feet of the mighty Walter Baader but why did he name the populations that way round???:D)

I guess because it's one of those things where they were sorted into categories before the details were understood? I find the supernova classification scheme hard to remember as its based on light-curve characteristics. Still, not as bad as Benji Franklin and his labelling of electric charge (not technically wrong as its arbitrary, but we're most familiar with flowing electric current in the form of electrons).

Edited by Knight of Clear Skies

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On ‎04‎/‎04‎/‎2019 at 09:13, Knight of Clear Skies said:

I guess because it's one of those things where they were sorted into categories before the details were understood? I find the supernova classification scheme hard to remember as its based on light-curve characteristics. Still, not as bad as Benji Franklin and his labelling of electric charge (not technically wrong as its arbitrary, but we're most familiar with flowing electric current in the form of elections). 

"elections"? Call the Moderators now, I feel the B word coming on...:grin:

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