Collimation off? 10" Omegon Dobsonian.

[Battleminexl1]

Hello there! Been using my telescope without issues for months on end, managed to collimate it once which greatly improved the views (The main mirror central dot was way off). Been away from home for a few months now and just recently got back, so I took my 10" Dob with me to a field and my views weren't good at all. No where near as good as the were a few months back. Mars just looked like a fuzzy orange ball, not sure if it could've been the thin layer of clouds which was causing the terrible seeing, but still a little confused. The telescope hasn't been touched or changed since I last used it and the collimation stills looks good, the main mirror doesn't seem to be off at all.

Only thing I noticed is the reflection which I've marked in the picture below seems to be a little too "high" up? It doesn't look completely centered. 

So, my question is, does this collimation look good? Should the secondary mirror be adjusted to move the reflection I marked "down" a little more?

 

Extremely thankful for any help!

[Peter Drew]

Depends a bit on the focal ratio, if f5 or "faster" the offset looks about right if the focuser is at the bottom of the picture.  External issues are more likely to be the issue.      😀

[Battleminexl1]

14 hours ago, Peter Drew said:

Depends a bit on the focal ratio, if f5 or "faster" the offset looks about right if the focuser is at the bottom of the picture.  External issues are more likely to be the issue.      😀

Alright! Thanks a lot for the clarification, will give it another go tonight since the clouds have finally cleared up, hoping for some good views!

[Spile]

In order to make an assessment, you need to be able to see the whole of the focus tube and I would also place a piece of coloured paper behind the focuser as per…