M31 Andromeda and NGC7635 Bubble Nebula

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longinthetooth
Posts: 29
Joined: 12 Aug 2007, 22:36
Location: Kirkcaldy

M31 Andromeda and NGC7635 Bubble Nebula

Postby longinthetooth » 29 Sep 2017, 10:16

Bubble nebula 210917 equalised low curve sat 17.jpg
Bubble nebula 210917 equalised low curve sat 17.jpg (1.68 MiB) Viewed 662 times
M31b.jpg
M31b.jpg (1.49 MiB) Viewed 662 times
Hi folks,
I've been using a Baader modded 450D for the last couple of years but recently had my 700D similarly modded and these 2 images represent my first nights out with this camera. The telescope is an f/7 102 triplet apo refractor with a 0.8 reducer/flattener which brings it down to f/5.6. The mount is an AZEQ6GT, equatorially mounted on a pier inside a modified shed with a roll off roof. Light pollution is an issue - we're right in the middle of Kirkcaldy.
Both images are unguided 30 x 2 minute subframes, 15 matched darks, 30 flats and 20 bias frames stacked in Deep Sky Stacker and post processed in Photoshop with the help of the Astronomy Tools add on. I use a CLS clip filter in the camera to help with the light pollution.
I'm very happy with the performance of the telescope and mount which allow me to take 2 to 3 minute subs without noticeable trailing. My polar alignment is getting better so my subs may get longer. (I was using an LX200 SCT until earlier this year and while it was great for visual I had little success with it for deep sky photography). So I ended up biting the bullet and buying new gear more suited to what I wanted to do. This new gear, permanently mounted, has made a huge difference.
Next steps:-
Improve my polar alignment so I can take longer subs.
Take more lights to increase the signal to noise ratio.
Start experimenting with guiding - yet another "black art" I have no experience with!
Improve my post processing technique - I'm sure more experienced folk could bring out better results.
I have a thermo electric cooler which I've seen used to cool DSLRs. There are walk throughs available on Youtube. Mmmmm more DIY!
I'm considering, however, a cooled astro camera as a step up from DSLR.
Resurrect the LX200 for planetary work. This would mean longer focal lengths and short exposures - perhaps a new planetary camera .....?
I'm looking forward to the darker nights!

John B
Altair Astro 102 EDT on Skywatcher AZEQ6GT pier mounted, Baader modded Canon 700D, 10" Meade LX200 deforked, Meade DSI3 OSC. Swift Model 831, Roll off roof observatory, plus loads of bits which may come in handy ...one day...

Opel star
Posts: 104
Joined: 29 Feb 2012, 00:25
Location: Rosyth

Re: M31 Andromeda and NGC7635 Bubble Nebula

Postby Opel star » 01 Oct 2017, 22:02

Wow! Hats off to you! Your bubble nebula is stunning.
Money well spent I think.
Chris

longinthetooth
Posts: 29
Joined: 12 Aug 2007, 22:36
Location: Kirkcaldy

Re: M31 Andromeda and NGC7635 Bubble Nebula

Postby longinthetooth » 02 Oct 2017, 18:30

Thanks Chris. It's very much a work in progress. I'd love to get velvety black backgrounds and more colour! Still progress is being made!
JB
Altair Astro 102 EDT on Skywatcher AZEQ6GT pier mounted, Baader modded Canon 700D, 10" Meade LX200 deforked, Meade DSI3 OSC. Swift Model 831, Roll off roof observatory, plus loads of bits which may come in handy ...one day...

Dariusz
Posts: 27
Joined: 04 Nov 2016, 12:59

Re: M31 Andromeda and NGC7635 Bubble Nebula

Postby Dariusz » 04 Oct 2017, 21:09

Hi John
The NGC7635 looks great.... congrat. for the setup.
Lots of details but I think the M31 is little over processed and the natural colours sunk under the overexposed data.
Try to keep the levels similar. I guess you have a lot blue due to the LP filter to deal with??
Last week I've eventually put my mount back to one piece and a chance to try it was on this same night and the aim was among others M31
This is a single frame with little process.
L_0011_ISO400_240s__NA kopia.jpg
L_0011_ISO400_240s__NA kopia.jpg (2.01 MiB) Viewed 472 times


Canon unmod. 600D/iso400/240s no filters NEQ6 unguided APM80/480

Defo I need a field flattener but I was checking mostly the belt drive upgrade on NEQ6.
5 min was not as good but later I've found some alignment issues.
Clear Skies
Dariusz

longinthetooth
Posts: 29
Joined: 12 Aug 2007, 22:36
Location: Kirkcaldy

Re: M31 Andromeda and NGC7635 Bubble Nebula

Postby longinthetooth » 05 Oct 2017, 07:53

Hi Dariusz and thanks for your input.
NGC7635 is a crop, the central portion of the stacked frame. Like you I had some issues with the edges and corners despite the fact that I have a .8 reducer/field flattener in the way.
M31 I'd agree with you about the processing. It's difficult to know when to "stop"! At what point do you reach the best result possible with the stacked image you start with? Now I may get better at this with more practice but I do find this aspect of the hobby a real challenge. Also I'm not sure yet the best I can expect from my light polluted sky. I may be overprocessing because there isn't the potential to get a better result.
I'm using Photoshop CS6 and Astronomy Tools:
http://www.prodigitalsoftware.com/Astro ... rsion.html
They really simplify post processing and (theoretically) should get you a better result.
What did you mean by "keep the levels similar"? Did you mean colour channels?

I can definitely improve both the acquisition and processing of the data.
I think longer sub frames might help. I've been limited to 2 to 3 minutes thus far but I think my polar alignment is improving. I used the polar alignment routine outlined in the Skywatcher AZEQ6GT user guide. I had previously struggled using other methods largely due to my limited view of the sky - not being able to view suggested alignment stars. Drift alignment looks awfully complicated to me..... :?
There's always guiding..... I've not got to that yet!
Your 4 minute sub looks good, and at iso 400! I must give that a try.
Cheers
JB
Altair Astro 102 EDT on Skywatcher AZEQ6GT pier mounted, Baader modded Canon 700D, 10" Meade LX200 deforked, Meade DSI3 OSC. Swift Model 831, Roll off roof observatory, plus loads of bits which may come in handy ...one day...

Dariusz
Posts: 27
Joined: 04 Nov 2016, 12:59

Re: M31 Andromeda and NGC7635 Bubble Nebula

Postby Dariusz » 05 Oct 2017, 14:59

I try to keep the processing as simple as possible. Keep an eye on the histogram (seen after ctrl & L) the graph should be smooth if you push too far it becomes divided by lines. The background levels should be as close as possible R,G,B min value about 30 , in your photo, something bad happened to G chanell. Half of it is overprocessed and I cant sort it back.
When using LP filter it means that for start you have to extend exposure time or ISO in order to compensate the lost of light. I have this same LP filter but haven't got a chance to use it yet.TBH the only good solution for LP is to go to under as dark sky as possible.
I use the polar scope for polar alignment since I had the first scope and so far it works quite well, just make sure the polar scope is aligned its self.
The mod. of your canon sounds quite interesting and I'm wondering what is the max sensible exposure time until the noise is too nasty?
Personally, I think Canon is enough for unguided shots too max 3-4 min and later the S/N ratio is unacceptable. It might be different in your moded Canon. Could you post any photos of that MOD plz?
Guiding
In my case, I like the idea of QHY mini guide scope plus my QHY5LC as its light and easy to use It is just fine due to the relatively small aperture of my scope 80mm. That setup might not be enough for 100mm due to required better tracking resolution.
As Canon is not an option for 20min or longer shots if you are going to use narrow bands filters the next step is cooled CCD, colour or mono is a neverending dilema. The best is decide what do you want to get from your work. The difference is lower resolution-quality in one shoot colour CCD compare to mono used with RGB filters and..... cost LoL. I think that the required time to collect the data is similar as eventually instead of 60x colour shots you need 20x RGB to get similar signal.
Clear Skies
Dariusz

longinthetooth
Posts: 29
Joined: 12 Aug 2007, 22:36
Location: Kirkcaldy

Re: M31 Andromeda and NGC7635 Bubble Nebula

Postby longinthetooth » 05 Oct 2017, 16:53

Hi Dariusz - interested in your comments re colour channels. My colour perception is not very good - something my wife points out frequently! I've watched youtube videos showing astro photo processing (Deep Sky Stacker and PS) but I've always thought they would likely be starting out with a better image to begin with! I haven't yet worked out just how much is possible under my sky with my kit. I live next to a council car park which has tall, bright lighting which spoils my eastward horizon. It is a constant source of skyglow. Both M31 and NGC7635 were, however, high up in the west(ish) when I imaged them so I can't blame the LP for every blemish!
I'd be happy to make the raw stacked image available to you to process - interesting to see what someone else could make of it. Maybe you'd need the whole stack to start the process from the beginning? If you're interested perhaps that could be arranged.
On polar alignment - the AZEQ6GT has a polar scope but the reticle markings are not the usual ones, and, the reticle does not turn with the RA axis to "put 0 at the highest position" (which I think it should). I reluctantly decided to polar align without the polar scope. I won't go into the details here but my alignment has improved and next decent night I'll try longer subs.
The ISO setting I used was 1600 - being the first night out with the modded 700d I wanted to compare results with photos I had taken previously with a similarly modded 450d. I think noise is a little less, and maybe a little more detail. I also want to try a lower ISO.
I had the 700d modified by:
http://cheapastrophotography.vpweb.co.uk/
and the details of the Baader mod are there.
If the mod interests you, you could have the 450d to try out since at the moment it is surplus.
Neither camera is currently cooled but I have most of the makings for a peltier cooler mod which I saw on Youtube (google Martin Pyott canon 600D peltier mod). I've not decided yet whether to do this....maybe aye maybe naw!
Guiding - I have a DSI3 bought many moons ago which I'll try as a guider. My AA102EDT scope is fitted with a 60mm finder which I think I can guide through - in theory I know roughly what to do but, as we all know, when it comes time to try for real, something always goes wrong!
Cooled cameras - these look interesting....
https://www.atik-cameras.com/news/atik- ... ta-launch/
8)
Cheers
John B
Altair Astro 102 EDT on Skywatcher AZEQ6GT pier mounted, Baader modded Canon 700D, 10" Meade LX200 deforked, Meade DSI3 OSC. Swift Model 831, Roll off roof observatory, plus loads of bits which may come in handy ...one day...

Dariusz
Posts: 27
Joined: 04 Nov 2016, 12:59

Re: M31 Andromeda and NGC7635 Bubble Nebula

Postby Dariusz » 10 Oct 2017, 18:34

John
How big is the stacked file, do you think you could send it through an email?

longinthetooth
Posts: 29
Joined: 12 Aug 2007, 22:36
Location: Kirkcaldy

Re: M31 Andromeda and NGC7635 Bubble Nebula

Postby longinthetooth » 11 Oct 2017, 08:29

Thanks Dariusz. It will be interesting to see your result. For the 700d the stacked image is 106mb. (For the 450d they're about 70mb). If you have a gmail address you can access my google drive. I'll place the stacked image there and pm you.
Best
JB
Altair Astro 102 EDT on Skywatcher AZEQ6GT pier mounted, Baader modded Canon 700D, 10" Meade LX200 deforked, Meade DSI3 OSC. Swift Model 831, Roll off roof observatory, plus loads of bits which may come in handy ...one day...

Dariusz
Posts: 27
Joined: 04 Nov 2016, 12:59

Re: M31 Andromeda and NGC7635 Bubble Nebula

Postby Dariusz » 14 Oct 2017, 20:11

HI all
Got some time to work with data of Johns' M31
I've stacked and did
some basic process with PS and for the background I've used fitswork4 as it was quite uneven.
TBH Despite the fact that there is still a lot to do with the details I like the result.
I'm happy to answer any questions
Clear skies
Dariusz
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