I recently acquired this tripod and was wondering what this screw is and what I need to do to make this tripod usable with a DSLR.
The screw seems to be a bit wider than half an inch.
What kind of adapter might I need to fit a common tripod head?
Basically they sell you either a incomplete tripod or you just need to buy a tripod head:
There are several options to choose from and some brands sell the tripods and heads as separate parts.