E-mail Received, 24 April 2006
Hello Brian,
Having looked at your website for the Museum of the Broadcast TV Camera
I was interested in your comment about the left-handed 'beer handle' for
the Mk3.
I attach a very poor quality picture of such a beast, although I have
no idea how it was achieved - all the mechanism and tube were on the right-hand
side - and any transverse shaft would have impeded the viewfinder movement.
I am familiar with the layout, as I operated this type for quite a few
years, heavy beast that it was. A couple of comments may be amusing. Marconi
in their wisdom, provided a 'dustbin lid', a black metal rubber edged
bung to stop up the tube-housing, presumably to keep dust out when not
in service, but they tended not to be used at all.
Hence, inserting the bung when de-rigging could provide some amusing moments
when next the camera was rigged. Racks operators and engineers were generally
not amused after the fruitless efforts to find the 'electronic' fault!
The ND filter, in service parlance 'The Wedge', was a two stop range and
normal practice was to set it half-way in its travel and then set the
manual irises, thus giving a crude 'stop either way' degree of control.
This was fine until you had to start swapping the waterhouse stops used
on the folded 25" and 40" OB lenses. Try that in a howling gale
on a 100 foot scaffold tower when the light suddenly changes and the racks
guy needs more light. The Mk4 was a welcome relief with its iris motor,
however you will find that the original Mk4 had a Marconi badge on the
nose of the iris motor and in later versions it was replaced with a large
rubber bung. This was to allow the operator to free the jammed iris motor
when all four lens irises failed to rotate in sync. or their clutches
jammed. The method used was to try to rotate a knurled knob situated on
the end of the motor shaft, the problem being that the motor was still
trying to push the shaft around and when freed could almost take your
fingers with it.
Your comments about safety when attempting to restore old gear, the dangerous
voltages etc. remind me of a couple of things. We were required on occasion
to operate in negative mode, this entailed pushing a button on the back
of the head amp. and then to reverse, pull the button out again. I was
never convinced by the assurances that there were no stray high voltages
floating around on the back of the tube, generally the camera was on-air
when the switching was needed, so you had to reach in down the end of
the tube housing, not able to pull the tube up towards you (defocusing
the camera), all a bit dodgy.
A colleague found-out one day that even with the covers on it still could
be a dangerous beast. The small door on the rear that covered the talkback
controls, in its open position, allowed a convenient ledge for keeping
a pencil, he was returning his pencil (silver propelling type) to it storage
position when he managed to insert it into the live pin of the F&E
mains socket, ........noise on transmission was always frowned upon!!
Best wishes
Annon.