Hi, I'm finishing building a 6 inch f/5 binoscope but I'm unsure about size of secondary mirrors. Bino is calculated for 1,25 inch diagonals for now but it has 2 inch focusers. Of course I shortened the primary-secondary distance by factor of length of the diagonal light path which is about 75 mm (about 3 inches).
I'm pretty sure that stock secondary mirrors won't be able to deliver 100% of light and the bino will need a bigger secondary. Can you help me calculate size of the secondaries?