It's not the mount.
It's the OTA and it's dovetail bracket, rings, focuser,
diagonal, adapters, flexure and collimation.
We are squaring the DEC axis with the OTA's optical
axis.
1. Make sure everything about the
OTA/focuser/rings/dovetail/etc. are tight and smooth. No flexure
anywhere.
2. Do a careful collimation, as appropriate for OTA
type.
3. Evaluate flexure as described in the AP
manual.
4. Shim one of the ends of the OTA's rings/base/dovetail with
appropriate material, such as cuttings from the side of an aluminum pop
can.
5. Only one
end will ever need to be shimmed, not both.
6. Go back to
step 3 and repeat until error is minimized.
Note that
future collimation changes will effect orthogonality.
Also note
that when polar aligned and the OTA has no flexure, orthogonality-induced
pointing error will only be in the E-W direction. This can help to
find objects quickly in spite of suffering from orthogonality
error.
I hope this
helps.
Christopher Erickson
Consulting Engineer
Summit
Kinetics
Waikoloa, HI 96738
www.summitkinetics.com
Yes, if I recal on the other side of the meridian, it points well.
Do you have any perspective on how to address non-orthogonality on the AP900?
Mike