Shim

[vlazg]

Looking at my latest images, with pretty good alignment and guiding, my stars are still slightly elongated, it seems to be in the same direction so I'm thinking my camera might not be orthogonal.
How do you make and use shims to adjust this? Being a visual learner is there any links that will show this.
Cheers
George

[rustigsmed]

hi george,

i would test to make sure it isn't non perfect polar alignment. you can test this by trying shorter exposures and comparing the star elongation between them.

russ

[raymo]

With your setup polar aligned, do a few exposures of 2, 3, 5, 8, and 10 sec. With even reasonable polar alignment stars will not elongate in
such a short time. If all your resulting pics show the stars equally elongated then your camera is almost certainly not perpendicular to
the light path.
raymo

[vlazg]

Thanks Raymo and Russ,
Might get a chance tonight, will give it a go

:)