Quote:
Originally Posted by multiweb
Having owned that scope previously maybe I can pitch in a few things to check unless you have further modded it.
1_ Secondary is fine. No astigmatism there and the bond on the alu plate is very light. No stress.
2_ Primary is not clipped. Rubber just holds the mirror. No pinching.
3_ Focuser is as square as I could get it. Having said that this scope is very hard to collimated perfectly.
Good think is once it is it holds collimation very well. MPCC (type I) spacing is critical as well. From memory my spacing was around 58mm, not the recommended 55mm.
Regarding star shapes this is probably as good as it'll get. If you get astigmatism rotate the primary and try again until it's gone. That's how I found the sweet spot. |
Thanks for the feedback Marc. I am using a different (larger) secondary now, as I had to cut the tube short to achieve DSLR focus - the original secondary once it was moved closer to the primary proved too small. I am suspicious of the secondary i'm using now (its from my GSO dob), and am considering getting a new secondary mirror and fixing it to the secondary holder that you originally supplied.
I also want to check the primary rubbers as i wonder if they are too tight following the last time I cleaned the mirror. Rotating the primary to find the 'sweet spot' is a good idea - thanks
