Note: I knew I had to have a fixed distance between the rear of the scope and the camera chip. I looked and looked but could not find the correct M54 size extensions that I needed. (I have since learned that I can have these made to order - Precise Parts of Florida). I came up with the idea of downsizing to M48 - inserting M48 extensions as required (and easily obtainable) - and then upsizing to M54 again. It all looks a bit much now (as I think of all the connections) but I can verify that it works and I have continued with this rig when not using an extender or reducer. Again - all part of the steep learning process......and I suppose all part of the fun!
The original setup was for the Atik 460 EX which has now been replaced by the QSI 6120i - but the connections for prime focus imaging remain as I first put them together.
With 0.73x Reducer