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Author Topic: First LRGB - IC1396 Elephants Trunk  (Read 879 times)

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Offline midnight_lightning

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First LRGB - IC1396 Elephants Trunk
« on: 21:54:54, 21 August, 2017 »
Hi,

I finally got an hour or two without clouds at the weekend and tried LRGB with my new SX814 camera using SGPro.
It was only a test and I only got about one hour integration before the clouds rolled in but I was hoping for better results - any pointers would be welcome.
LRG = 4 x 240sec each
B = 5 x 240s (Blue got 1 extra - not intended!)
All Bin 1x1

(I also took 2 x 900sec HA but haven't used these yet (I haven't worked out how - also I'm not sure 900sec was long enough(?) )

I'm wondering if 240sec lights are too short for this target?

This image is cropped to get rid of blue LP (?) in one corner. Any suggestions on how to deal with LP with LRGB? When I was using DSLR I was using an IDAS LP filter which worked really well for nebula (not great for galaxies though).

I did have one success which still has me smiling - watching SGPro do a Meridian Flip; re-acquire the target; start tracking and continue shooting. I really like SGP so far, a focuser is next on my list :)

I also have a couple of PHD2 questions. Firstly, calibration takes about 10-15 minutes, I use the settings that PHD generates, is it normal to take so long? Secondly, SGP calibrates PHD when I run the sequence, is there a way to stop this so that I can calibrate prior to running the sequence?

Thanks

Mid
HEQ5 Pro (Belt Mod), Sky Watcher Esprit Pro 80/400, SX Mini Filter Wheel with OAG - Lodestar X2, SX814, Software - SGPro, PHD2, Stellarium (Scope), EQMOD, DSS, Star Tools.

Offline Einari

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Re: First LRGB - IC1396 Elephants Trunk
« Reply #1 on: 08:16:41, 22 August, 2017 »
I think you need more subs and longer as well.
Regarding calibration time - make sure you have set the guide camera's pixel size and guidescope's focal length and use the calibration step calculator and input the proper calibration step size it suggests
Tapio

Celestron C8, C9.25" & Hyperstar, iOptron CEM60-EC, TS 80 triplet,  Coronado PST, SXV-694,  ASI120MM/ASI174MC Cool

Offline midnight_lightning

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Re: First LRGB - IC1396 Elephants Trunk
« Reply #2 on: 08:11:08, 23 August, 2017 »
Thanks Einari, am I right in thinking the length of exposure would account for the lack of nebulously and the number of exposures affects noise/quality. What length of exposure should I try?
I think I have tracked the LP down to the luminance so perhaps I need an LP filter when using this filter - although this would be a pita as my filter goes in the flattener.
PHD I need to investigate, I did use the calibration step calculator and the figure it gave was over 8000 step ms. The sidereal rate figure in the calculator is 0.1 which seems very low, I have been using this since I first started guiding but can't remember why. Perhaps this accounts for the long calibration although I have no idea how long it should take.

Moving to LRGB is proving harder than I expected, my list of issues to fix is still getting longer :)
Mid
HEQ5 Pro (Belt Mod), Sky Watcher Esprit Pro 80/400, SX Mini Filter Wheel with OAG - Lodestar X2, SX814, Software - SGPro, PHD2, Stellarium (Scope), EQMOD, DSS, Star Tools.

Offline Einari

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Re: First LRGB - IC1396 Elephants Trunk
« Reply #3 on: 09:56:12, 23 August, 2017 »
You are right about the length/number considerations.
Try longer L subs as there's your detail - maybe 6 to 10 minutes.
Regarding LP - usually focal reducers have 2" threads so you could put your LP filter there.
And you could try add Ha to formula.
There are tutorials to be found how to do this.
Tapio

Celestron C8, C9.25" & Hyperstar, iOptron CEM60-EC, TS 80 triplet,  Coronado PST, SXV-694,  ASI120MM/ASI174MC Cool

Offline midnight_lightning

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Re: First LRGB - IC1396 Elephants Trunk
« Reply #4 on: 18:35:36, 24 August, 2017 »
Ok, thanks Einari. I have an IDAS LP to go in the flattener but it would mean stripping the rig down every time I want to do RGB :( 
HEQ5 Pro (Belt Mod), Sky Watcher Esprit Pro 80/400, SX Mini Filter Wheel with OAG - Lodestar X2, SX814, Software - SGPro, PHD2, Stellarium (Scope), EQMOD, DSS, Star Tools.

Offline Eccoskies

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Re: First LRGB - IC1396 Elephants Trunk
« Reply #5 on: 19:41:25, 24 August, 2017 »
Mid,

These targets respond far better in narrowband rather than LRGB - in fact if you process your 2x900s Ha shots (good sub length by the way  :thumbup:) then you'll find theres quite a lot in there. Also narrowband isn't affected by light pollution so it's one less problem to try and solve  :thumbup:

Regarding PHD calibration : where in the sky did you calibrate? Ideally you need to be as low down in the south as you can  :thumbup:

Mark
Mark
53N 1W

Pair of binos and a beer

Offline midnight_lightning

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Re: First LRGB - IC1396 Elephants Trunk
« Reply #6 on: 21:57:10, 24 August, 2017 »
Hi Mark,

That's interesting, I will try processing the HA and see what I get.

I always calibrate PHD on my target - sounds like I have been doing that wrong, I generally choose targets that are directly overhead to improve seeing, so should I always calibrate low South and then slew to target?

Thanks
Mid
HEQ5 Pro (Belt Mod), Sky Watcher Esprit Pro 80/400, SX Mini Filter Wheel with OAG - Lodestar X2, SX814, Software - SGPro, PHD2, Stellarium (Scope), EQMOD, DSS, Star Tools.

Offline midnight_lightning

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Re: First LRGB - IC1396 Elephants Trunk
« Reply #7 on: 19:45:40, 25 August, 2017 »
I've had a go at processing the Ha, it's a bit noisy but perhaps not bad for 2x 900s - I'm glad I got something out of the session, thanks for suggesting it.
I have clipped this a bit pushing development so perhaps 1200s would be better next time?
HEQ5 Pro (Belt Mod), Sky Watcher Esprit Pro 80/400, SX Mini Filter Wheel with OAG - Lodestar X2, SX814, Software - SGPro, PHD2, Stellarium (Scope), EQMOD, DSS, Star Tools.

 

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