Adjusting secondary on skyliner 150p

[Steve777]

Hi All,

Ashamed to say though I've had my 'cope a while now, only just coming round to collimation!! (The views were good). Anyway, I'm pretty sure I've grasped the principle of collimation from numerous sources, but I'm just wanting to check how I adjust the secondary on my 'scope (it is not square to the focuser); I assume you have to loosen the three bolts by allen key before you can turn the centre screw? And that you then adust the three bolts again to tilt the mirror? Would greatly appreciate input.

Thanks.

[wookie1965]

That is correct the middle screw only moves the secondary further in the tube or out of the tube (OTA) the 3 screws adjust the tilt of the mirror. You will have to loosen one to adjust a different one once completed check that all are nipped up I.E not loose as the mirror would move just slightly turn screw up until it stops not to adjust, and when adjusting don't go to hard as they will leave indents on the mirror holder then it will never collimate right. I had to rub mine down then put plastic washers in collimation is a doddle  now.

[Steve777]

Thank you; do you have to loosen the three screws to move the one in the middle? (Very stiff)

[wookie1965]

Yes you do you will find once you back off the three screws the middle screw will become easy.

[AlexB67]

Another useful tip, use very small delicate turns at a time on each. When I did the first time on my smaller Dob I turned the screws too much, before you know it is like having to start afresh and the secondary is all over the place.  That is not a bad way if you want to learn staring from scratch, but usually the factory secondary setting should be fairly close and only tweaking is needed.   A small tilt adjustment can be achieved with say 1/4 turn on two of the outer screws and the other way round for the third, or vice versa so the whole thing does not get very loose in the process.

Have fun with collimation

[66mikeg]

It's a good idea to have the tube horizontal before adjusting the secondary else if you're too enthusiastic with the screwdriver / allen key the secondary can make a mess of the primary mirror