Special characteristics which only reflectors possess, can be found under this heading.
Main mirror construction
Here, the construction type means the geometric shape of the primary mirror.
Secondary mirror heating
This heater prevents condensation on a reflecting telescope’s secondary mirror.
Secondary mirror obstruction
The shadow effect of the telescope optics due to the secondary mirror, because this lies in the optical path.
Ventilation for primary mirror
Fan for a quicker alignment of the mirror temperature to the ambient temperature.