[NeilW]

Hi,

I recently purchased a Glatter 1.25" laser collimator and TuBlug combination for my 8" solid tube dob. Using the collimator, I align the beam from the secondary in the centre spot of the primary, but then using the TuBlug to adjust the primary, when the shadow of the "donut" of the primary centre spot is correctly adjusted to fall in the centre of the TuBlug white screen, the red "target pattern" on the screen is way off.

I seem to be missing something crucial here, and it's probably quite simple, but can someone give me some guidance?

Thanks,