NGC4236 galaxy in Draco
Posted 11 April 2021 - 05:46 AM
finally I finished processing of a new image.
It is NGC4236, a barred spiral galaxy in Draco.
I started this last year in April but was not that happy with the data. So this year I added some more frames.
- lukasik, dswtan, lambermo and 17 others like this
Posted 11 April 2021 - 05:59 AM
Beautiful and sharp.
This object is rather dim in the outer arms and as such
can use all the time you want to expose!!
Posted 11 April 2021 - 07:43 AM
Oh man, I really like this image. Tremendous detail. Well done!
Posted 12 April 2021 - 12:10 PM
Dear Mert, Max-OP and Mike,
thank you for your encouraging comments.
Also thanks to all the likers .
- elmiko likes this
Posted 12 April 2021 - 02:17 PM
excellent image Andreas, sharp and colorfull very well done !
I have a similar telescope as yours with also the GPU corrector but I struggle to get nice stars in the corners. Which value of the backfocus did you settle with ? Thanks,
Posted 13 April 2021 - 03:27 PM
the stars in the corners of my images are also not perfect. I always have at least one dirty corner .
The distance of my chip to the corrector is around 54mm with my 8 inch f/4. On my 12 inch f/4 I add 0.5mm more.
The table below shows the recommended values for f/4 newtonians. If You have filters in the optical path, You have to take their thickness into account.
ACHTUNG, der optimale Arbeitsabstand ist brennweitenabhängig und non-linear! Der Korrekor muss auch die Bildfeldkrümmung ebnen. Besonders bei kurzbrennweitigen Newtons zu beachten!
Die Tabelle gilt für f/4 Newtons, langsamere Newtons kommen mit 55mm Abstand gut aus.
F=600mm, Arbeitsabstand = 51,66mm
F=800mm, Arbeitsabstand = 53,66mm
F=1000mm, Arbeitsabstand = 55,0mm
F=1200mm, Arbeitsabstand = 54,66mm
ab 1500mm, Arbeitsabstand 54,60mm
(Source : Teleskop-Austria)
Edited by Andreas_Roerig, 13 April 2021 - 04:06 PM.