[cpoc]

I recently got back into the Dobsonian world of observing (having previously had I think a 8" but had to sell that one) with a Bintel 10" scope.
I've had some lovely views through it... but wanted to try attaching my DSLR. When attempting that I got the familiar lack of ability to focus.
I removed the eyepiece adapter and attached the T ring direct to the focus mount but still not quite there.
I bought a barlow and that didn't seem to help either.
Then I read about changing the collimation bolts for longer ones, great I thought, no permanent damage to the tube and relatively cheap.
I did a quick check and found that while my locking bolts are a fairly standard m6... the collimation bolts are m7 (of which Bunnings only had 35mm varieties).

Fortunately there's a bolt specialist near home and they set me up with some 50mm and 60mm bolts.

I've swapped all the bolts over and performed a rough collimation (my eye seems to be center of the viewfinder again).
But I'm wondering how much movement I have of the primary mirror. I'm not sure how much change I've made so far though I suspect the mirror is now at least a little bit further up the tube, I still have quite a lot of thread left on my bolts that would allow me to theoretically move it quite a bit further up... but how much movement room do I have before I'd risk damaging the mirror/telescope?


If I get clear skies tonight I will try and take it out and see if I can attain focus (though there's not much that I can spot that is likely to be easy to see on my camera, planets are too low down before dark and the moon is only a slither and also low).