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First Deep Sky Image and Processing - M31 - I think I need help

russp

By russp
in Getting Started With Imaging

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russp

russp

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So Saturday I went out and set the scope up in the light, got some nice pictures of the moon waiting for polaris to become visible and then after polar aligning set the scope up on the Andromeda Galaxy. Haven't tried to set up guiding yet (figured I'd try stumbling before running) so limited myself to 2 minute subs (upping ISO to 800 to compensate) and gathered 30 of them using an intervalometer and just the lcd screen for focus. Been kicking myself for not adjusting the framing better but I guess the in thrill of actually seeing something there I forgot that step! 

Tried DSS but it just wouldn't stack the images without running out of memory (probably because I'm running it on a mac in wineskin) so downloaded the trial pixInsight and just spent the afternoon working through the tutorials with my data. 

Workflow was

Batch Preprocessing to process 20 darks 20 bias and 20 flats to align debayer and register with Winsorized Sigma clipping - a nice easy process

Image Integration to combine the registered lights

Dynamic Background Extraction

Colour Calibration - although not convinced this actually did much!

Histogram Transformation to stretch

Tried HDR multiscale transform - didn't like the result so discarded that step entirely

Masked Saturation boost

Finally another Histogram transform to increase the black background

and then a rotation and crop 

Below are the images - Given that it's a first go and I'd not touched a telescope until after christmas I'm pretty pleased but if anyone can offer help or advice on the process and where I need to improve or just do things a little differently I'd be very grateful. Have I overdone it? Not done enough? Need better data? All of the above?

Image after stacking

12309617126_f54d7166a0_b.jpg

Image after DBE

12309023445_2d46f34324_b.jpg

Image after Histogram Transformation 

12309023165_9b46271943_b.jpg

And My Final Rotated Image

12309023545_c9d66c05cb_b.jpg

If anyone is interested enough the full size jpegs are on my flickr page at  http://www.flickr.com/photos/russpinder/

and here's the fit file with all the stacked info in it https://www.dropbox.com/s/1oqonj7d3iz1uab/light_BINNING_1_DBE1.fit

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Zuben Elgenubi

Zuben Elgenubi

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Framing aside, that is really good for a first go! You should be very pleased indeed. It certainly puts my attempts at imaging M31 into perspective. Capturing the data is one thing, but it's the processing skills that really make the difference (or not in my case).

Once you are guiding and have got a bit more processing experience, I'm sure that you will be producing some amazing images  :smiley:

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Christopher Davenport

Christopher Davenport

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I would be well chuffed with that image, really nice for early days.  Nice kit in your sig.

Have a read of the book make every photon count, by Steve Richards, really informative and valuable when starting out.

Some ideas on capture you could vary your exposures and use layers to recombine short vs longer exposure to balance the brighter centre with the finer outer.

i.e I would get another 30 subs at 120sec on ISO 3200 and stack separately with darks (cappa sigma), then layer the two images with a mask.

Some kit ideas, with a focal reducer, you could flatten and reduce down Fstop and get a wider field of view. (M31 really needs this.)

Your mount should easily be able to track for 180 seconds without guiding so long as you accurately polar align (I use align master.)

Hmmm not much else, sorry, I am very much a noob myself, I am sure some body more experienced will be along soon to enlighten further. :)

Keep up the good work and persevere the weather will get better soon. (I hope)

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russp

russp

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Thanks for all the encouraging comments they're really appreciated 

Framing aside, that is really good for a first go! You should be very pleased indeed. It certainly puts my attempts at imaging M31 into perspective. Capturing the data is one thing, but it's the processing skills that really make the difference (or not in my case).

Once you are guiding and have got a bit more processing experience, I'm sure that you will be producing some amazing images  :smiley:

Processing took me literally all afternoon and that was after messing around and failing with DSS - it's certainly a steep learning curve - thank goodness for online video tutorials!

I would be well chuffed with that image, really nice for early days.  Nice kit in your sig.

Have a read of the book make every photon count, by Steve Richards, really informative and valuable when starting out.

Some ideas on capture you could vary your exposures and use layers to recombine short vs longer exposure to balance the brighter centre with the finer outer.

i.e I would get another 30 subs at 120sec on ISO 3200 and stack separately with darks (cappa sigma), then layer the two images with a mask.

Some kit ideas, with a focal reducer, you could flatten and reduce down Fstop and get a wider field of view. (M31 really needs this.)

Your mount should easily be able to track for 180 seconds without guiding so long as you accurately polar align (I use align master.)

Hmmm not much else, sorry, I am very much a noob myself, I am sure some body more experienced will be along soon to enlighten further. :)

Keep up the good work and persevere the weather will get better soon. (I hope)

Got the book thanks (it's been very useful as have another couple too) and a 0.8x focal reducer is on the way. Given how well it's tracked for 120secs I suspect you're right about 180 if I'm careful with polar aligning. I have the kit for guiding though and will be working on getting that going soon. I'm aligning with the polar scope - can't run alignmaster on a mac :( but there is a polar align function in eqmac which I must investigate. I do really like skysafari pro to use to control the scope though.

Cracking M31 pic. I'd be delighted with that. Telll me though - you say you didnt have guiding on. I'm just a rookie and dont know that mount - presumably you were driving, otherwise at 2 minutes you would have big trails, no?

The mount tracks I just don't have guiding via a separate camera set up yet so the tracking is only as good at the mount and the mount setup. Have to say am very impressed with the mount. 

I really need to get the camera connected to the pc for framing and focus as it's really hit and miss right now. Not even entirely sure if the image I have is focussed particularly well, some of the stars look awful big?

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ollypenrice

ollypenrice

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Very good indeed. You've learned that DSOs often grow once you give them long exposures!!

I don't think you got the absolute best out of DBE. Did you crop the edges of the image before processing? This is important because they always contain edge artefacts which confuse the histogram and mislead DBE. 

There is just a hint of edge darkening still.

After DBE I'd have been inclined to give it a shot of SCNR green.

Good stuff, nicely captured.

Olly

http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=2266922474&k=Sc3kgzc

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glowingturnip

glowingturnip

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very nicely done !

Just a humble suggestion from me, I think you could be a little lighter-handed on the histo transform.  If you look at your post-DBE image, there is a faint 3rd dust lane to the right of the core, with that bigger-than-normal star in the middle of it.  You can barely see that lane in the latter two images.  Maybe use curves transform to drop what is real background but keep all that faint outer stuff ?  Also, I think in the last two images the cores are just borderline saturated ?

Nit-picking though, they're excellent images, much better than my M31

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russp

russp

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Very good indeed. You've learned that DSOs often grow once you give them long exposures!!

I don't think you got the absolute best out of DBE. Did you crop the edges of the image before processing? This is important because they always contain edge artefacts which confuse the histogram and mislead DBE. 

There is just a hint of edge darkening still.

After DBE I'd have been inclined to give it a shot of SCNR green.

Good stuff, nicely captured.

Olly

http://ollypenrice.smugmug.com/Other/Best-of-Les-Granges/22435624_WLMPTM#!i=2266922474&k=Sc3kgzc

I din't crop the edges before DBE so you could well be right there and I'll have to revisit that - I did do a SCNR green, just forgot to include it in my workflow list but thankyou for the advice on DBE that sounds like it will be good general advice

very nicely done !

Just a humble suggestion from me, I think you could be a little lighter-handed on the histo transform.  If you look at your post-DBE image, there is a faint 3rd dust lane to the right of the core, with that bigger-than-normal star in the middle of it.  You can barely see that lane in the latter two images.  Maybe use curves transform to drop what is real background but keep all that faint outer stuff ?  Also, I think in the last two images the cores are just borderline saturated ?

Nit-picking though, they're excellent images, much better than my M31

You have a point, just the sort of suggestions I was hoping for, thankyou. I'll have a play with those ideas and see if I can get any more out of it - looks like there will be plenty of opportunity for processing over the next few stormy evenings while imaging is impossible :(  

very good! You could still play more by doing say, masked stretch, local hist eq, dark structure enhance, TGVdenoise etc. ....

I'll have a look at those tools too.. there's an awful lot of process's that I have no clue what they do!

Thanks again, I can see this hobby getting addictive!

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IanL

IanL

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Instead of using HistogramTransformation, try the new MaskedStretch process (was just added about a week ago).  It is still early days and everyone is learning how to use it so not much advice on the forums yet, but it will make a massive difference to colours in your stars.  At the moment they are basically white, but using masked stretch you should be able to get something more like this which was my first attempt with the new process:

M101 Widefield, Unmodded DSLR

You will find there is less contrast after applying MaskedStretch than you would get with a normal midtones transformation, so you may need to play about with additional transformations and/or curves. There are other (more advanced) ways of boosting contrast which I use but a bit much to explain in a few words.

Once you have done that, then you apply a curves stretch to boost saturation (Open the curves process, select the pink 'S' option along the bottom, and then drag a few points up to make the pink line curve upwards smoothly from bottom left to top right - you can make this quite a big/aggressive stretch but be prepared to also select 'L' at the bottom and gently tweak the bottom left of the L curve downwards if too much colour is appearing in the background).

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