At the time of 900GTO mount production, the orientation of the RA axis rear plate’s three attachment screws was not mechanically relevant. Consequently, there were some mounts produced that did not have their screw placement as shown in the linked photo. These mounts cannot use the RAP900 / RAPAS as sold. In some cases it may be possible to contact a machine shop and custom modify the RAP900 to remedy the problem. You will need to contact our technical support department for specific information.
Our Right-Angle Polar Alignment Scope can be used with the Mach1GTO and all 900 and 1200 mounts (except the original black version) when used with the appropriate mount adapter. Each mount type has its proprietary adapter. Additionally, if you have more than one of the same mount, each will require its own adapter. It is important to note that the adapters will add some dimension to the back of your mount which, if you have a carrying case, will require a small modification to the foam liner.
These adapters are push/pull adjustable for precise alignment. Once adjusted, they will retain their precision, allowing the polar alignment scope to be inserted and removed as needed (the adapter, itself, remains attached to the mount). This will also allow the polar scope to be used interchangeably with each of your mounts without further adjustment. The adapter’s alignment is what allows this precision polar alignment scope to provide consistent accuracy when re-installed repeatedly with either a single mount or when used with many different mounts.
In order to obtain extreme precision, it will be necessary to perform a precise polar alignment using a traditional drift alignment (visually or with CCD camera), or by using Ray Gralak’s PEMPro / Polar Align Wizard the first time that the RAPAS is used. Once the alignment is spot-on, the push/pull adjustment screws on the adapter are used to orient Polaris into its specific location on the reticle. For additional information see the Right-Angle Polar Alignment Scope.
The cap (also sold separately as M16106-A) is very convenient when transporting the mount, or if you wish to remove the polar scope after initial use. It provides protection and prevents dust or little critters from entering your mount's interior. It is included with the polar scope adapters.