andrew your still missing the point. you have a CF tube cool. what comes out the back of your telescope is aluminium.... and if im not mistaken RC's inherently have a whole lot of back focus so that you can add in your filter wheels OAG's field flatteners ect ect ect.
You just shot yourself in the foot because what you just took out over there is still over here.!? I smile every time somebody does something and thinks they have eliminated it and then preaches to the world. do the whole lot properly and then you can say you have eliminated it as i stated in my previous post.
As for 45 micron, can you honestly show me what 45 micron looks like? ill tell you now that 45 micron is BLOODY SMALL. and to give you a point to think about when talking about microns, what focuser do you use? if your using a manual focuser you make me laugh as i will 100% know you haven't got a hope of making a sub 500 micron adjustment. then you have to take in atmospheric conditions wow there goes your 45 micron again! I for one can sit there on a dead still night with a ED 80 on a EQ6 Pro mount and watch my FWHM jump from 2.3 to 1.6 and back up without touching the scope! If your using a really high end focuser aka Feather touch or even better with full robotic control, you would only be looking at 100 micron adjustments maybe a little less. but in the same case as i pointed out with my ED 80 setup your chasing seeing to a degree.
IMHO unless your talking about massive optics, super fast F ratios, and getting quality only seen in really high end optics/scopes your flogging the rotting carcass of the horse. sure make things as good as you can but save your sanity as there are alot of other things to worry about before you start worrying about a 45 micron shift in 800-1 meter of tubing!
