I found the solution thanks to Vincent at High Point Scientific... Thanks Vincent ... Hopefully this might help another Takahashi and Atik owner. Item Part # Backfocus remaining Takahashi TCA1020 55 55 Takahashi Wide T-threads Takahashi TCD0012 13.7 41.3 Takahashi Wide T-threads to T-threads Baader T2-25C 7.5 33.8 T-thread to T-thread extension Tube Atik MFW 19.5 14.3 Telescope side (female T-threads), Camera side (male T-threads) Atik Filters -1 15.3 Assuming 3mm thick filters (1/3rd filter thickness) Atik Flange 2 13.3 T-thread flange on filter wheel (comes with filter wheel) Atik 414EX 13.5 -0.2 Ends in female T-threads All numbers are in Millimeters This system chart shows you the backfocus form the TCA1020 that you already have. Then the adapters needed as well as the parts from Atik and the distances they take up. Note that we're off by 0.2mm's which is not an issue. There will be tolerance issues that will compensate for this, but also the filter wheel flange allows for a slight bit of adjustment, which should be enough to allow you to reach optimal correction from your reducer.