the mk3 MPCC has the removable T-mount thread so you can screw straight into the M48 thread behind makes it 57.5mm backfocus instead of 55mm
the spaceings are as followed
15mm CCD
25mm for Filterwheel minus one side thread because the OAG attaches directly to the SX filterwheel)
13mm for OAG
4mm for the MPCC to OAG adaptor
15+25+13+4= 57mm
add on .66mm for the 2mm thick baader filters and you get 57.66mm optical path
