Newbie M101 Processing

Questions and answers about processing in StarTools and how to accomplish certain tasks.

Newbie M101 Processing

Postby Astrowebby » Wed Mar 15, 2017 1:27 am

Hi everyone
As a newcomer to astro processing, I am very interested in StarTools as powerful yet straightforward imaging solution.
Have used it a couple of times to evaluate and achieved (with my basic equipment) files I was happy with.
However, this new file presents all sorts of issues I have never come across before and cant seem to resolve.
The image was taken in a (not too badly) light polluted backyard, but the moon was out
The stack is about 1.5 hours of subs, stacked in DSS (with darks, flats and bias frames) using the standard methods mentioned many times on this site.
Is it possible that this image is too poor to process?

When I process the image using Autodev, bin, crop, wipe, autodev at this point the image looks awfully grainy and nothing I can do will recover.
Can someone with more insight into StarTools give me some pointers on what to do to process more effectively?
Or where I might have gone wrong previously with stacking the images?

The FTS file is available as follows:

The frustrating thing is that I can see there is data available, but I lack the experience to be able to tease it out.

Many thanks for your anticipated assistance
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Re: Newbie M101 Processing

Postby admin » Fri Mar 17, 2017 3:58 am

Hi Andy,

Thanks for uploading the data. I had a look, and it is very challenging data indeed.
What sort of exposure times and settings/ISO were you using? Could you tell us a bit about your setup?

Galaxies like these have very low surface brightness, making even more important to make every photon count - imaging with the moon out is detrimental in that case.
As a result, there is indeed very little deep data to tease out.

If you ever watch a video on astrophotography, let it be this one.
(don't watch any other videos of this expo though - they are of markedly less quality!)
It's an absolutely brilliant presentation by Craig Stark (the author of Nebulosity amongst other things), expertly explaining - amongst other things - to you how/why signal to noise is a lot worse when there is added light (for example when the moon is out).
Ivo Jager
StarTools creator and astronomy enthusiast
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Re: Newbie M101 Processing

Postby Astrowebby » Fri Mar 17, 2017 2:07 pm

Hi Ivo
Thanks for looking at my poor attempts!
I have spent a long time digesting and reading up on short exposure astrophotography as my current setup is somewhat limited.
This was the result of an evenings work, with my Canon 50D attached to my Skywatcher ST102.
As mentioned, the moon was almost full, and I expected that there would be some effect on the resulting image,
I used BYE to manage the exposures, and took 150 lights of 45s duration at ISO400 (selected as it appeared to give a better live view image in the conditions, and is the suggested ISO value for this Canon model after which dynamic range decreases with higher ISO values).
At the same time I took 40 dark subs at same duration and ISO setting, and 40 bias shots at the highest shutter speed.
I used flats taken previously which were at ISO800 (having gone over it again, could this be an issue?)
All combined in DSS (v1.3 - had some issues with the later version so had to revert back) keeping 80%.

With all of that, I managed to work with StarTools to obtain an image which, while it has its problems, I am fairly chuffed with!
2017-03-16.jpg (67.75 KiB) Viewed 104 times

Couldn't have done it without StarTools simple sliders to review in live what actions are being performed.
However, realise that I still have much to learn, and am looking forward to reviewing the video you have suggested.
Any comments/recommendations for improvement warmly welcomed.
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