Focuser change & collimation/frac

[jetstream]

I may change the focuser on the SW120ED. If this is done how is the new focuser lined up collimation wise? I'm thinking of a rack Feathertouch. Any thoughts are appreciated, thanks, Gerry

[Dave In Vermont]

I recently swapped out a focuser on a ST80 (not an optical equal to your scope). Pulled out my laser and checked the collimation by inserting same in the focuser, it was half a lens off through the achromatic objectives. So I got rid of the stock focuser. The new Crayford from GSO/Revelation was square-on. My point: A laser will show you if you are on the spot by seeing where the laser hits your front lens. Don't do this with a diagonal in it - that can throw it off.

With the scope you have, I would hope it's stock-focuser is quite well aligned.

Clear Skies,

Dave

[sbooder]

You can use a short tube Cheshire EP to collimate a frac too.

[jetstream]

Thanks guys, the 120ED star tests well and I think its existing focuser is centered and square. It is not designed to handle the recent heavy loads I'm placing on it so a change might be in order. The lens cell on the ED's are not collimatable ( I think) so if the new focuser turned out to be off, what are the solutions? or if this one is good the replacement would be good too? I've never had a refractor focuser off and don't want to go backwards. Great idea about the laser and Cheshire BTW- thanks.