Collimation With Al's Reticle

[Mav359]

In my head this makes sense so there is a good chance i'm wrong and thought i'd throw this out for an opinion...

I have been collimating my scope, ive my scope way out of focus and have my DSLR in so i can work on the end of the scope whilst watching the screen. I got pretty close to centre but then though how do you really know your centred, my eye for this probably isn't as good as the more experienced collimiators out there. So i took a 10sec photo of Pollux and then placed Al's Reticle over the top and increased the reticule size to match the stars outer ring, then reduced the reticule size to the next set of rings and eventually to the centre. (see attached)

In my head if your lined up with the outer circle and if you are properly collimated then as you reduce the reticule size then it should match all of the inner cirlce's because your concentric.

Have i finally contributed a good idea? Or more likely , Why am i wrong?

[Merlin66]

Al has actually developed a new reticle overlay specifically to assist with collimation!!

Al's Collaid V1.1

AlsCollAidV11.zip

[Mav359]

typical!!!

Cheers Merlin66 i'll check that out

[cathalferris]

(if the scope is a Newt) I would have expected that the shadow of the diagonal at this far out of focus to be off centre when perfectly collimated - as there is an offset for even field illumination. This shouldn't affect the just inside and outside of focus images.

If it's a SCT or MCT, then concentric should be good.. but its the in-focus star images on-axis that will be the determining factor, not the out of focus images