>A refinement just occurred to me. Your method assumes the fork arms are
>exactly paralell with the RA axis. If they are not, there can be some
>error. What about this slight revision....
>
>Place a white cardboard on the base over the RA axis as in your method,
>attached to the RA bolt so that it does NOT move when the scope is moved in
>RA. Concentric circles on the cardboard will help here too.
>
>Now, rotate the scope in RA only. Adjust the DEC and the OTA adjustment
>screws (and the fork arms if needed) so that as the scope is rotated in RA
>there is no motion of the light cone on the stationary screen.

[Paul responds to his own post]

OOPS! After some visualization work, I think I have decided that if the
OTA is parallel to the RA axis, mis-aligned fork arms will NOT affect
pointing accuracy, but WILL affect the alignment as has been described. If
you visualize the fork tilted, say, 45° away from parallel to the RA axis,
pointing accuracy would still be OK if the OTA was actually parallel to the
RA axis at 90° DEC. However, in the same scenario, aligning as has been
described would cause the OTA to be mis-aligned by 45° when the light cone
was centered on the RA bolt.

Bottom line seems to be that any fork alignment error will show up in the
final OTA alignment.


Paul Goelz
Rochester Hills, MI
pgoelz at eaglequest dot com

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