Quote:
Originally Posted by JC17
Hi Marc (and anyone else!)
I will upload a few images to show what I am seeing. Clearly the star donuts are brighter to the bottom left - both inside and outside of focus. The secondary shadow is also offset to the bottom left. So now to work out what that really means and how to fix it so any tips would be welcome.
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Yup clearly out of collimation - the DSI method is your friend (in fact I've come to the conclusion that once you've roughly centred the axis and spot, throw away the Tak and go DSI - it's surprisingly quick once you've got the hang of it).
As a few have mentioned, if yours in the older solid tube model with the primary attached to the focuser, then you might have challenges keeping it in collimation - if you send a photo of the back plate through, we can probably figure that out.
The GREAT thing about these scopes is that once you've mastered collimation a). pretty much everything else is easier after this and b) as Paul mentioned, you will get some LOVELY images!
Once you've reached final collimation you will want to check the spacing - preferably with a Ronchi, otherwise plate solve to determine your actual focal length and compare that to the stated specs (2000mm from memory) which can then be adjusted either via the knurled ring on the secondary or careful adjustment of the primary (moving all three screws in/out the EXACT same number of turns) or getting really courageous and adjusting the central screw on the secondary (VERY MUCH NOT RECOMMENDED UNLESS YOU ARE BRAVE/FOOLISH).
Chris Woodhouse book has an excellent section dedicated to the fine art of RC collimation, I would consider it mandatory reading. (the whole book in fact)