C11 xlt secondary not centered??

[cyberblitz]

Hi,


Not sure if this is supposed to be like this, but the secondary mirror in my C11 XLT is not precisely centered. Is this normal??

[Merlin66]

"Commercial Tolerance"
May be good enough to perform to specifications.

[raymo]

It may work out that when the scope is properly collimated, so by
definition the secondary is in the correct position, that the support for the
secondary is improperly positioned rather than the mirror, which wouldn't
matter at all.
raymo

[Sitt]

There was a Facebook post this morning of the secondary mirror coming away from the housing. Apparently the mirror is only stuck to the secondary housing with double sided tape. This guy sent his scope back to Celestron as collamation wouldn't hold. Celestron sent it back finding no fault.

[multiweb]

That looks like a big offset indeed. Do you have issues collimating the scope?

[cyberblitz]

Yea, i did notice the double sticky pads but they seem to be holding the mirror pretty firm for me at least. I suppose this is the cheapeast way to hold the mirror. I suppose this is the problem with mass produced scopes.

[cyberblitz]

That's the problem, I don't know. You see, I have had problems with focusing objects but I'm not sure if it's to do with my lack of experience with this type of scope. I owned a 10" Newtonian for 8 years and recently upgraded to the C11 XLT. One of the main issues I have had is focusing and I'm trying to determine why. As far as I can tell, the scope is collimated, at least when viewing the airy disk. However, i have noticed the airy disk will appear non centered depending on the scopes orientation. I have since learned about mirror flop/image shift with these types of scopes, which has been extremely frustrating to experience, especially imaging at high focal lengths i do (6000-7000mm for plantery imaging).

The issue I have experienced is acclimation of the scope; cooling this scope takes an age because its a closed system and there are no vents on the back with this non-edge version.

So, im just trying to understand the scope and rule things out. I have been told that if the secondary is off by even a few mm, it can cause soft images.

[Outcast]

With respect to cooling your SCT, you might like to read this & change tack..

https://www.iceinspace.com.au/forum/showthread.php?t=172245&highlight=sct+insulation

I now own the 7" Intes featured by Mental4Astro complete with corflute insulation/dewshield... works like a charm

Others who have gone down the path of insulation rather than cooling have had similarly good results...

It's a rather inexpensive option to try

[multiweb]

If you have an alignment issue the secondary shadow will be off center in and out of focus on the opposite side. You could check that out after collimating the scope on a star next time you're out.