It may only be an adaptor but this little piece of anodised metal will let you use a range of popular astroimaging cameras with Baader’s Universal Filter Changer (UFC) on Celestron’s RASA 8″ telescope thus allowing you to swap filters quickly and easily.
Unlike the Baader UFC telescope adaptors for the 11″ and 14″ RASA’s (see image below) that are mated to the corrector lens group cell face-plate and secured with the knurled retaining ring, this adaptor screws onto the male outer threads of the lens group housing itself. So you would remove the RASA 8’s retaining, the T-2 or C camera adaptor and then the clear filter, and then attach the UFC Base with its RASA 8 UFC adaptor in place. The adaptor has female M84 threads on the telescope side and uses Baader’s S70 dovetail on the UFC/camera side for secure fitment to both the RASA and the UFC Base.
This S70 UFC adaptor itself only adds a minuscule 1.4mm to the optical path, but what is the overall optical length with the rest of UFC system in place? The UFC base is 13mm thick, and with the typical types of UFC camera adaptors (T-2/M48 etc) used being 2mm, the overall optical length is 16.4mm (1.4mm+13mm+2mm). The RASA 8 without any of the camera adaptors attached has a back focus distance of 29mm, this leaves 12.6mm so with a filter in place this configuration is suitable for use with a wide range of popular imaging cameras with ~13mm backfocus.
Below shows an example set up using 2″ mounted filter slider and with a camera that uses a T-2 mount, and the new Baader RASA 8″ UFC adaptor.