Pye Mk4 Television Camera Turret close up

The Pye Mk4 used a variable neutral density filter with a range of 100 to 1 to control the exposure of the Image Orthicon tube. It can be seen through the open lens mounting position as a reflecting surface.

This technique was also used on the earlier Marconi Mk III. There is a 5 position filter ring in addition the the variable filter.
The small switch, top right, selects local or remote control for operation of the variable neutral density filter.
The complete turret can be quickly removed by undoing the large central fixing knob.

Some cameras have a motor to drive the iris on the lens, the camera in this pictures does not but camera serial number 22 does have such a drive and the lenses are adapted with a gear quadrant to mesh with the drive mechanism.