3.1 Primary Focus
With the Cassegrain optic the primary reflector focus is usable only if the secondary reflector is completely retracted. Behind the mirror a movable positioner is installed, equipped with 3 receiver bays.
Fig. 3.2 : Primary focus feed positioner
The primary mirrror focal length is nearly 10.3 m, therefore the focal ratio is F1/D ≈ 0.32.
Fig. 3.3 : Primary focus (dimensions : mm)