Centring focuser/secondary

[jason.p]

I've been trying without success to centre my focuser and secondary. I can get the mirror pretty well circular but no ammount of adjusting either the central screw or the three adjusting screws will move the position of the mirror in the focuser. As far as I can tell by "rough" measurement the secondary is central in the tube. (I'm using a Catseye cap). I'd be grateful for any advice.

Thanks

Jason

[boabsta]

Perhaps your focus tube is off angle?

[Neil I]

Looks like the secondary is too far down the tube. Easily fixed by carefully unscrewing the 3 secondary adjustment screws slightly and the tightening the central secondary screw to move the secondary towards the spider. Smaller side to side adjustments can then be made with the 3 secondary screws. Make sure to make all adjustments with the ota tube horizontal so that nothing can roll down the tube and hit the primary. If you search SGL you'll find some very good instructions that explain the process much better than I have ;-)

[LeeB]

If you have done the above and there is no more travel up the tube, a meade 10" lightbridge I fixed had the fins of the spider the wrong way round. The tal should have the travel though.

[jason.p]

Looks like the secondary is too far down the tube. Easily fixed by carefully unscrewing the 3 secondary adjustment screws slightly and the tightening the central secondary screw to move the secondary towards the spider. Smaller side to side adjustments can then be made with the 3 secondary screws. Make sure to make all adjustments with the ota tube horizontal so that nothing can roll down the tube and hit the primary. If you search SGL you'll find some very good instructions that explain the process much better than I have ;-)

Thanks Neil . Seems like the secondary was miles out. I've pulled it back what seems like a heck of a lot and got it more or less central now. Just a bit more tweaking and it should be as good as I can get it

Thanks again

Jason