Focuser alignment

[Astrosharkey]

I think I possibly  have a focuser alignment issue with my 8' skywatcher Newtonian, I am pretty sure it is well collimated but last night after checking I rotated the laser and in inscribed a circle on the Primary.  As  a double check when I put my camera on with a CCTV wide FOV lens on it did not appear to be centralised compared to the electronic cross hairs generated by sharpcap.  Is this a focuser alignment issue or have I just cuffed my collimation (star test was ggod)?

[Waldemar]

you will have to collimate your laser before using it.
That is done by laying the laser in a V-shaped wedge and point it to a piece of paper on a wall
Mark the spot where the laser beam hits the paper.
Now rotate the laser in the V-shaped wedge. If well collimated it shoud stay in the same spot and is ready to use.
If not adjust the three centering screws on the fore end of the laser until it is.

 

[paul mc c]

Another way to check if the focuser is off,after the laser is collimated,  if you can position the ota so as the focuser is pointing straight up,ie towards the sky/ceiling and then drop the laser in to the focuser with out tightning it up, gently rotate it,put a piece of paper opposite the focuser and mark where the beam hits,if the focuser is square the dot should not move off the dot.

[Astrosharkey]

Thanks both, just checked my laser, looks a little out so will sort that then recheck the focuser and I guess yet again collimate it.  It was the video centre out compared to the electronic that had me confused, any ideas?

[michael8554]

Whether the focuser is tilted or not, rotating the laser should not scribe a circle, it should remain a spot, even if off centre.

So sounds like the laser needs collimating as suggested.

Michael