I'd like to order a custom made ring for a field flattener compensated for a total distance from the frontal part of the adapter plate of OAG-8300 attached to STF-8300M camera with FW5 filter wheel - to the CCD plane. I'd like to know your best evaluation of this distance (and also without OAG-8300). There are some contradicting figures I've found in the manuals which do not line up with my attempts to measure it. Thank you.