Ric,
it is a bayonet type fitting. I can't answer the question about it fitting onto the C8 back. I'll have a look later today and let you know some more info..
More info: was bought for a Minolta X-300 model film SLR, the fitting is an MD bayonet (I think). A 1.25" nose piece from a Meade camera adapter screws into the t-ring without a problem, so it should screw onto the C8 as well
cheers
Mark