I recently purchased the STX-16803 Ultimate package which includes the camera and FW7 filter wheel, followed by the STX-guider and the AO-X. The Optical Backfocus chart for the STX-series cameras doesn't list the STX-guider backfocus component, but the product literature for the guider says that it takes up 1.1-inches (27.9mm). I would like to confirm that my backfocus is the sum of 67.1mm (camera/FW7/3mm filters) plus 27.9mm (STX-guider) plus 26.6mm (AO-X) plus 17.1mm (3-inch accessory ring). This totals 138.7mm of backfocus. Do I have this correct? Thank you in advance!