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Old 16-02-2019, 01:08 PM
Startrek (Martin)
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NGC 5139 Omega Centauri

Captured some lunar images between 9pm and 11pm then waited until 1.00am for the sky to darken then captured Omega Centauri. Finished subs at 2.30am, set my darks, put the cover over the scope and went to bed
30 x 3 minute subs
15 x darks
ISO 800
PHD2 guiding
Stacked in DSS
Processed in Startools
My stars on the right hand side of my recent images keep flaring a bit. Iíve pulled apart the OTA, collimated and aligned with a Cheshire and 2 different lasers secondary and primary and looks ok to me nice and concentric. My test images on small and big stars before I image are really good, clean, sharp and nice diffraction spikes.It canít be focus as the test stars are tight and sharp and if it was coma you would see it on both sides ?
Must be a bit of flexure or something as itís only on the right hand side off axis
It is a budget Bintel GSO $299 OTA
A bit annoying
Cheers
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  #2  
Old 16-02-2019, 01:26 PM
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rcheshire (Rowland)
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Still a nice image. Could it be camera tilt?
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Old 16-02-2019, 02:45 PM
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Gee Martin I would be very happy with that image...it really is excellent in my view.
Dont let the very minor issue of those stars take away from all that has turned out very well.
...crop it a little ☺

Great effort no question.
Alex
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Old 16-02-2019, 03:54 PM
Startrek (Martin)
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Thanks gents
Rowland
My DSLR t ring adapter inserts into the focuser pretty square and tight with just a nip up of the locking screws plus GSOís have better focusers than Skywatcher and other brands , so itís a very remote possibility that itís tilt
It must be my OTA optical train somewhere canít be anything else
Alex
You always give positive feedback and encouragement, I like to squeeze as much out of my little budget set up as possible to try a get a better image. I do like this image but we can always improve.When itís heading toward 3am in the morning you just want to finish up and get some sleep, just in case you trip over the tripod or something
The moon may be a hindrance to AP but you can work around it or do as I did use it to your advantage and take some really cool lunar vistas which I still have to process
Thanks again


Thanks again
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Old 16-02-2019, 06:04 PM
Paulyman (Paul)
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That looks great, I love the different coloured stars throughout the cluster.
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Old 16-02-2019, 06:19 PM
raymo
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Could still be tilt between the T ring and the camera. Try inserting a very thin
shim of whatever material you have between the T ring and the camera in
the same direction as the star elongation; it will either make it much worse or much better if it is tilt, or almost no change if it is not.
raymo
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Old 16-02-2019, 09:01 PM
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ChrisV (Chris)
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That's really a beautiful image Martin.

Definitely tilt and probably with the focuser. I had same with my GSO. Shims up a side of the focuser. Just write notes on which side you put the shims and which way it changed the flaring. Yours doesn't look as bad as mine was. It takes a surprisingly lot to get it right. I had to shim mine by about 2mm - it still needs a bit more.
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Old 16-02-2019, 09:49 PM
Startrek (Martin)
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Thanks

Iím out imaging IC2602 Southern Pleiades and noticed on the first couple of 2 minute subs that the off axis stars flare away to the outside borders on all four sides now ( not just the righthand side ) all the on axis stars including the main stars are ok nice and round
Any ideas ??
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Old 17-02-2019, 01:02 AM
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Ant0nio (Tony)
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That is a lovely image of one my favourite objects Martin, perfect star colours in my view.
Tony
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Old 17-02-2019, 01:43 AM
Startrek (Martin)
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Tony
Thanks for the kind comments, appreciate it
Iíve been guiding for about 8 months now and it makes all the difference even on Star clusters like Omega as you can gather so much more data to work with
Prior to guiding I was struggling to get 50 or 60 sec subs which doesnít expose enough
Cheers
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