Hello,
I am having some trouble collimating my 12inch f4.5 truss dobsonian and getting different results between the Cheshire and the laser method.
Everything looks very aligned through the Cheshire key (picture attached)...however if I then insert the laser, everything is not aligned, the reflection of the secondary is not hitting the centre of the circle of the Primary and the reflection of the Laser is way off....(pictures attached)
I have been told that 'the reflection of the secondary in the primary will not be centered with the other reflections, but that ok, as the secondary itself is not exactly centered on the optical path (there is a tilt, which is due to the focal ratio ( fd 4,5). If it where fd 5 or more, it would be centered, and there would not be any tilt'
If this is the case, then I guess it is normal for the laser not to be aligned or am i missing something ? Thanks a lot for the help :)'