To connect my DMK firewire camera to my Questar axial port, I use a C-mount to T-mount adapter, available on eBay for 19.95 from a vendor named alsmiley. It also has threads for a 1.25 inch IR cutoff filter. The adapter also slip fits a 2" focuser. At right is the Questar axial port camera adapter, but the male threads on the Questar adapter are not an exact match for the standard T-mount adapter. I use it anyway, taking care not to tighten the assembly too much.