[Dbroz (Daniel)]

Hi everyone

I am new to this site. My name is Daniel and I am building a 18” truss telescope. The question I have is what diameter should the upper cage be compared to the 18” F/5 primary. The mirror is 457mm diameter and I made the inside upper cage at 520mm, is this too big? I’ve been reading a few diy jobs and I’ve seen that the cage should be only half an inch bigger than the mirror. Mine being 2.7” bigger I’m starting to think it’s too big and I will have trouble finding focus. My secondary is 3.1”. If I can have any feedback on this it would be much appreciated.

Thank you all in advance

Daniel