View Single Post
  #1  
Old 24-08-2019, 10:13 AM
Paul Haese's Avatar
Paul Haese
Registered User

Paul Haese is offline
 
Join Date: Jan 2009
Location: Adelaide
Posts: 9,393
Barnard's Galaxy Test image

Well what seems like an interminable hell appears to be finally coming to an end with the OOUK AG12. It has taken a month or so to work out the spacing to the Wynne to sensor and the slight tilt on the camera. This meant driving down to the observatory a couple of times a week to make adjustments. I don't have a stable enough mount at home to bring the scope home, make the necessary changes and test, so I have had to leave the scope down there; making a change, then test the next clear night. It is a tedious arrangement but has worked in the end. Many hours of driving over the last 16 months has been due to the problems with this scope.

It would be good if OOUK would actually give accurate back focus measurements for their corrector too. I have found that it is not 79mm +/- 1mm from the last optical element. It is about 3mm less in this case. I tried this spacing before Stefan fixed the corrector and it did not even come close to producing this sort of field. Stars were like badly shaped comets or double stars on one side of the field and nice round stars on the other. In fact no matter which way I tried I could never get both side looking flat. At one point I began to question whether I was in fact collimating the telescope correctly. This caused many hours of driving or bringing the scope home to try and eliminate what I thought was my own fault. I was completely wrong in trusting this notion. I sought advice from plenty of people despite knowing I was doing the right thing, every time experienced Newtonian owners would look at the collimation and say it looks perfect. All along it was the pig of a Wynne that was causing most of the issues.

This image is really just a test; it is short of time, seeing was not great last night and it's not processed well. There is still a bit of spacing error but at least it appears to be manageable now. Another tweak should have it near perfect. Collimation could be looked at a little too, but its not that bad. I could probably live with this anyway for a while just so I can get some runs on the board with this corrector and scope. The GPU I was using is an excellent corrector but it keeps the scope to f4, has a small backfocus and small corrected field. The Wynne supplied by OOUK makes the scope an f3.8 and is supposed to have a much larger corrected field. Which means I could use a much larger sensor on the scope to do more diverse targets.

So hopefully the end of this sorry saga is almost over. I owe a debt of gratitude to quite a few people for helping me out to sort this problem and to keep me somewhat sane.
Attached Thumbnails
Click for full-size image (NGC6822 LHaRGB 70 40 25 25 25.jpg)
125.6 KB57 views

Last edited by Paul Haese; 31-08-2019 at 01:59 PM.
Reply With Quote