Do I have a Collimation Issue?
Posted 07 May 2014 - 08:38 PM
I was out last night doing some visual with my 8se and something caught my attention while I was in the process of doing my 2 star alignment. My first star for alignment was Sirus and bringing my OTA into focus I noticed my scope could be out of collimation, but I’m not too sure.
The reason for me not being too sure is (out of focus) the central donut ring looks to be quite central and good but the outer ring seems more like a 80 to 95% full moon type of effect or a section of the outer ring is missing. Is this a collimation issue? If so how do I correct this? I am familiar with the collimation process for my old newt scope as I did it every night before going out, but not so sure with a SCT. I have heard Bob’s Knobs mentioned on here plenty of times on here as a collimation aid but I have noticed 3 or 4 screws on the secondary mirror plate and wondering if it’s a matter of tweaking these screws to get good collimation?
Thanks for reading and I hope to get a reply soon.
Posted 07 May 2014 - 08:57 PM
Posted 09 May 2014 - 06:26 PM
also collimate without the use of a diagnol
Unless you normally do not use a diagonal while observing, the diagonal should be in place while collimating. Once you begin the collimation process, be sure you do not rotate the diagonal. Since the diagonal itself is probably not "perfect" doing so will alter the center of the field and change collimation.
Posted 09 May 2014 - 06:42 PM
if your diagnol isn't properly aligned then that could pose issues as well.
Posted 12 May 2014 - 08:54 AM
Then, try different eyepieces to see if you get the same result.
Try another star, just in case something is blocking your view.
Then I would make a very slight adjustment to one collimation screw, and see if it has any effect on what you're seeing. If not, reverse the adjustment.
Posted 16 May 2014 - 11:38 AM