Focuser problem

[wookie1965]

My friend bought a 8" orion optics scope which had a low profile focuser on needed several extensions to focus as think it was set up for imaging. 

So bought a focuser think it's astro revelation and installed it. 

Took it out tonight put 40mm in and it focuses right near the very edge of the out focus. 

Put a 20mm in and cannot get focus even all the way in has anyone got any ideas please. 

[joe aguiar]

Sounds like u still need a extender or do u know if they moved main mirror up 2 inches for imaging?

If so can you move the mirror back down 2 inches?

joejaguar

Edited March 27, 2020 by joe aguiar

[wookie1965]

He has bought a extension the 2" one you get with Skywatcher telescopes tried it with it in and out won't reach focus. 

[Second Time Around]

The Orion Optics Dobs have a focal plane 100mm from the outside of the tube.

As Joe said you may be able to move the mirror further down to the bottom of the tube.  On my OOUK Dob there are 2 sets of holes, and my mirror cell uses the upper holes.

If you're just a little off you may be able to move the mirror enough by loosening all the mirror cell screws.

[wookie1965]

Spoke to him said the primary mirror cell is as far down the tube as possible I have just said if he still cannot reach focus move the mirror forward to the other set of holes and try that. 

[wookie1965]

Thank you all sorted moved the mirror forward got pin sharp stars now. 

Thank you so much. 

[Neil H]

Hi guys thanks again you have it sorted for me and thanks Paul for phone support

I really don't know why just by changing the focuser I had to move the main mirror forward  the new focuser has the same travel as the old one , and I put mirror back now it came out