[Joshua Bunn (Joshua)]

Thanks Jase,

I agree, it should hold. I recently put some more tension on the spider vein screws so i will see if that makes a difference.

having to refocus due to temperature changes - yes, but not focuser movement, thats not right. i mean the focuser is always pulled down by gravity.

im going to do what PW say and refocus where i want to image and see what the results are. There are also 2 alen head bolts on the focuser that are used as hard stops for focuser travel. im going to clamp them down lightly on the focuser draw-tube so it cant move and try the images again.

Jase, i really cant be sure whats moving, the secondary support or focuser. The above paragraph should eliminate the focuser and i was going to strengthen the secondary supports so i could tighten the spider veins more, but i can see you point, and for now, you probably right. however i can see where the secondary could do with some strengthening just to totally eliminate the secondary - but for now i will leave it.

there is evidence of astigmatism in the scope. see the zipped folder bellow for the document which shows a series of images on one side of focus, through focus then to the other side. what this is due to is another matter. it could be from shifting collimation from the secondary as i slew to a low altitude. I should perform this test at the zenith hey.

PW said its probably less than 1/4 wave astigmatism but hard to tell with the test images i provided. they would need to have it in their workshop to be certain of a result.

Josh