Hey Gary,
Here are a couple of photos of the setup.
Centre of reducer/flattener to sensor is ~ 100-110mm. Recommended distance for this reducer is 105mm so it seems I have just got it spot on.
Rob
http://users.tpg.com.au/en1gma83/photo1.jpg
http://users.tpg.com.au/en1gma83/photo.jpg