The telescope-side of the UFC-base carries a receptor with 6 clamp screws in 60° spacings, to mount all the Baader S 70-dovetail-adapters and spacers. A number of rigid UFC-S 70 extensions is available in 5/15/40 mm length, as well as an ultra-stable S 70 VARI-LOCK extension, engraved with millimeter scale and being seamlessly adjustable from 15 to 20mm. These four extensions will allow precise adaption with almost any backfocus situation.