Here are images showing the spacer ring Ben Lizdas made from PVC tubing so that he could use the Swarovski Digitial Camera Adapter for his Leica Televid spotting scope and
Pentax K100D D-SLR.
According to Ben, the inner diameter of the ring is 2.00", outer is 2.20" and the height is .40". The spacer ring slips over the eyepiece and then the bottom section of the Swarovski DCA fits snug against the ring, rendering a functional and elegant design.
If you're considering a small point-and-shoot digital camera that lacks an accessory thread, it still makes more sense to use
Leica's digiscoping adapter.
All images © 2007 Mike McDowell