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)