I recently bought a fast Newtonian astrograph and while I have been able to get collimation pretty close, I could never nail it. I have tried to collimate it so many times over the last couple of months it has almost driven me insane
I just could not work out what I was doing wrong.
Tonight I gave it another go and again failed.
While talking to a friend about it, an image flashed in my head of the spider and it's offset, so I had a good look and I had the sudden realisation that this OTA has been built with the spider's offset working TOWARD the focuser, rather than away!!!
The offset is approx. 5mm (154mm f3.9 with a 66mm secondary), so 10mm from where it should be.
So, before I drill 8 new holes in the nice glossy Carbon Fibre tube to rotate the spider 180 deg, my questions are.....
- How much of an effect will this incorrect offset(10mm) have on my being able to collimate properly?
- Could it also explain the halo's around stars in my images if the collimation is close, but not perfect?
It's a shame it wasn't installed correctly in the first place as the CF tube is now going to look like swiss cheese
