Marconi MkIII Television Camera type BD687
The Marconi MkIII Image Orthicon camera
was available with either 3" or 4.5" tubes. The tube was installed
from the front of the camera, the complete turret assembly could be
removed by slackening the 4 large bolts in each corner of the turret
housing. In operation the irises on the lenses were preset to the same
value, say f5.6, this gave the same depth of field for each lens and
the exposure was controlled by means of a motor driven graduated neutral
density filter. The turret was operated by a crank handle at the rear
of the camera and the "beer pump" handle moved the tube and
its yoke for focusing. It was possible to move the focus control to
the other side of the camera, but I have only seen this done once.
The "Taking" lens is the bottom left position near the red
cue light.
The complete camera channels are Studio = BD808, Mobile = BD809