[Astromelb]

Dear John (thebonz),

Thank you for your enquiry.
The system has two separate precision made Takahashi assemblies that attach to the spider and enable either a Cassegrain operation, or with the separate assembly a Newtonian operation.

The Newtonian process then fits up the included Takahashi focuser that attaches to the recess on the side of the OTA near the top where the black plastic plug is located in the pics.

The assemblies that fit into the spider are very cleverly sleeved and edge profiled - so that they only fit correctly every time and only in one configuration and attach with a simple tensioning screw.

There is no need for recollimation, as once set and with the clever design that Takahashi have utilised for this design you can change from Newtonian to Cassegrain or the other way around in just a few minutes and do not need to recollimate, as having correct collimation the system in the first place the alignment is retained.

There is no adjustment to the collimation on the primary mirror required.

Trust this assists.