The photo below shows the optical tube assembly (OTA) configured for prime focus flat-field photograhy. The secondary mirror is removed so that the light path passes through the flat field corrector and filter wheel.
Vibrations from the floor must not propagate to the telescope. Therefore, the concrete footing does not touch the floor, joists or battens. The pyramid-shaped footing is in contact only with the bedrock and the compacted gravel layer over the bedrock.