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Old 09-06-2013, 02:55 PM
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rmuhlack (Richard)
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NGC6744 Galaxy in Pavo

A series of firsts here. After a couple of test runs using camera lenses with my recently modded 1000D (stock Canon filter replaced with an Astrodon Inside UVIR blocking filter), this is the first imaging session using this camera with my main imaging scope - a truss modified VC200L with focal reducer.

Was also my first go using Sequence Generator Pro for image acquisition, just using the trial version at present. Was a bit anxious relying on an auto focus HFR routine rather than manually checking focus throughout with a Bahtinov mask. The plate solving and "centre here" feature is super duper though, and despite a few teething issues still to test out (like an automated meridian flip) i reckon this program (SGPro) is a keeper.

A prior "experiment" during the week indicated that subs at around 4mins at ISO1600 would give the maximum SNR ratio, so that is what I went with. This is 102 x 4min calibrated subs at ISO1600 imaged over two nights. Processed in PixInsight.

Hires version here: http://www.astrobin.com/full/44546/?mod=none

As always, comments and feedback most welcome.

[Edit: the attached chart shows the SNR of the 1000D at different ISO and exposure times, all relative to the SNR of my 400D at ISO800 5mins 20 C. I first did this experiment with the 400D at those conditions (see here), hence that is my baseline for comparison of alternative exposure conditions]
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Click for full-size image (NGC6744 1000D 2013 v1 sm.jpg)
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Click for full-size image (1000D SNR 6_5C.png)
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Last edited by rmuhlack; 11-06-2013 at 11:26 AM. Reason: SNR experiment details
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Old 09-06-2013, 02:56 PM
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Great job, Richard!
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Old 09-06-2013, 03:02 PM
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Excellent image Richard and I'm glad to see that SG pro is working out for you. I find SG Pro is a program I can't do without now. Good colour and processing as well of a difficult object to capture well.
Allan
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Old 09-06-2013, 05:57 PM
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strongmanmike (Michael)
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Sounds like a program I need

Lovely result on this majestic galaxy mate, a hard one to do well and this is well

Just watch that median filter it can reduce the noise but cause circular darker patches everywhere.

Mike
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Old 09-06-2013, 06:35 PM
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rmuhlack (Richard)
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Thanks guys

You're quite correct Mike. I've been using the Multiscale Median Transform process tool in PI for noise reduction. Its very effective, but I have noticed it has a tendency to produce a blotchy background with my data and the typical settings i've been playing with. I'm still learning the ropes there with how to get the most out of the tool without those negative artifacts.

I wonder if the 12bit AD converter and low QE of my uncooled DSLR is also partly to blame here - not really enough depth to the data or the requisite SNR to pull out the *really* faint stuff. Doesn't stop me trying though!

(Here's a greyscale comparison with an enhanced luminance image you might have seen before Mike... )
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Last edited by rmuhlack; 09-06-2013 at 09:50 PM.
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Old 09-06-2013, 06:39 PM
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Richard,

MMT is old hat. Have a go at TGVDenoise I tried it for the first time today and I'm pretty happy with it. Like all noise reduction algorithms, you have to use it sparingly...

Cheers,
Rick.
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Old 09-06-2013, 06:43 PM
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rmuhlack (Richard)
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Thanks for the tip! Will have to give it a try

(edit - just realised that it's not in v1.7 so i guess it's time to update versions)
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Old 09-06-2013, 06:50 PM
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Yep, I bit the bullet and upgraded. The current 1.8 seems reliable and has some nice improvements.
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Old 09-06-2013, 07:18 PM
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Nice one Richard; you've captured most of the faint outer extensions and processed the colours quite well.
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Old 09-06-2013, 09:15 PM
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Really nice image Richard ! Nicely processed, looks great
SGPro sounds like an interesting program worth checking out.
Erik

Last edited by E_ri_k; 10-06-2013 at 08:18 AM.
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Old 09-06-2013, 09:33 PM
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Nice image, Richard
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Old 10-06-2013, 10:09 AM
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I am amazed at the quality of this image. This would be a superb result for a $14,000 dedicated CCD. But a DSLR image - tremendous.

Its quite a faint galaxy and as Mike pointed out its a hard target.

Greg.
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Old 10-06-2013, 11:14 AM
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Thanks for the lovely comments everyone. I too am constantly amazed at just what is possible with relatively modest gear and dark skies

That said, there are some equipment issues still to work on (eg some star elongation in the bottom left corner, I cropped out the worst of it), dew has been a bit of a problem and I've noticed that the optics could probably do with a clean at some point as well. I'm still learning the ropes with PI as well. Guess it just means that there's still lots of room to improve and optimise, which is all part of the fun

Rick - I took the plunge and just moved up to PI v1.8, so will have a play with TGVDenoise.
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Old 10-06-2013, 04:44 PM
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astronobob (Bob)
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Smashing image Richard, great details and chunky background with the fainter galaxies etc, beauty photo
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Old 14-06-2013, 09:57 PM
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Great looking galaxy photo Richard.

Ross.
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Old 15-06-2013, 11:24 AM
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tilbrook@rbe.ne (Justin Tilbrook)
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Remarkable image Richard!

You have become a master of dslr work.

Cheers,

Justin.
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