Primary distance 200PDS ?

[leemanley]

Just a quick one, can anyone tell me the distance from the outside of their primary mirror to the outside edge of the OTA, got a feeling I have moved mine up too far when collimating, an inside measurement would be great in millimeters, any help greatly appreciated.

Lee

[Thalestris24]

Hi

I doubt if anyone knows that distance. I guess if you think you've moved it up too far then you could always just move it back again? I have a 150pds but have never felt the need to collimate it!

Louise

[Tinker1947]

If its to far up the tube the mirror will rattle as the springs that hold it steady will become loose, just wind the 3 adjusters back so the mirror is back down the bottom then undo them a turn...

[leemanley]

Just caught up with the post ! 
On closer inspection I noticed that the main locking bolts weren't touching the mirror, only the sprung thumbscrews, I found myself with a rare opportunity on Tuesday night, A CLEAR SKY !
Using liveview and Polaris I started to carry out a full collimation, secondary ( which was miles out for some reason) and primary. It took about an hour and a half faffing about in freezing temps but I persevered and can confirm that with warmer fingers and another half hour I'll achieve good collimation.
Thanks Lee