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Old 11-05-2019, 12:19 PM
sunslayr (David)
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M8

Hi all, this is my first real attempt at some astrophotography, still getting some kinks worked out with my framing I think there might be some J2000/JNOW coordinate conflicts but I would appreciate some feedback. This is the Lagoon Nebula, shot from my backyard. Its 38x600s shot with my new (to me) QHY8 non pro camera and final adjustments done in StarTools. Ill also put the uncropped image on Astrobin.
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Last edited by sunslayr; 11-05-2019 at 01:20 PM.
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Old 11-05-2019, 01:53 PM
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alpal
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Hi David,
not bad for a first attempt.
What was the seeing like?
Did you measure the subframes as you were going
with Maxim DL to see the FWHMs?
It seems like the stars are a bit bloated for some reason?
You might not have the coma corrector spacing exact & the collimation could be a little out
combined with not having an exact focus.
What did the guide graph look like?

Are you sure the blacks are not clipped?
I would have tried some selective contrast adjustment on the brightest
part of the nebula to make the image pop.


cheers
Allan
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Old 11-05-2019, 02:44 PM
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multiweb (Marc)
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Pretty bloody good for a first attempt David. You're a natural.
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Old 12-05-2019, 09:51 AM
sunslayr (David)
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Thanks for your advice, honestly it was probably a mix of all of the above. I might give the trial of ccd inspector a go and see if I can improve my focus and collimation. I think at the time I was getting an average of 4" for my FWHM. What I'm not sure of is how to get the distance for my coma corrector right. There seems to be conflicting measurements of the qhy8 ccd distance. Is the only way to check the distance is by adding a spacer, refocusing and then checking the FWHM of all the stars and then repeating?
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Old 12-05-2019, 01:29 PM
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Quote:
Originally Posted by sunslayr View Post
Thanks for your advice, honestly it was probably a mix of all of the above. I might give the trial of ccd inspector a go and see if I can improve my focus and collimation. I think at the time I was getting an average of 4" for my FWHM. What I'm not sure of is how to get the distance for my coma corrector right. There seems to be conflicting measurements of the qhy8 ccd distance. Is the only way to check the distance is by adding a spacer, refocusing and then checking the FWHM of all the stars and then repeating?



Hi David,
4 arc seconds is never going to give you a sharp image.


I got my spacing correct using a Varilock device as per here:
https://www.flickr.com/photos/247194...in/photostream

As you said - I used a trial version of CCD inspector here:
http://www.ccdware.com/products/ccdinspector/

There is also a great trick to get the collimation right
that only requires a laser collimator & a Barlow lens.
You need a paper re-enforcement on the mirror coloured black.
You basically look for the shadow of the re-enforcement in the 45 degree
viewing face of the laser collimator.
You adjust the 3 screws on the mirror until it's central.

I found focusing was very difficult without an electric focuser.
That way you're not bumping the scope while trying to focus.
I have a motorised 2" TS 2" UNC V-Power Newton Crayford Focuser.
The QHY software has a focusing software feature
which helps.


Still - your first image is excellent compared to whatever I did.
You're almost there with a few adjustments.


cheers
Allan
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