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B3404 Telecine

Page history last edited by David Samways 6 years, 3 months ago

 

 

 

 

1971 saw the start of the B3404 development. This made use of the automatic elements of the Mark VIII studio camera but with a number of changes to provide the specialised video processing. While the 35mm projector was standard the 16mm one was a brand new design. As the photo (taken in Sydney) shows, the whole system was now in one unit. There are two 35mm slide projectors under the desk. The cine projectors could be 35 or 16mm. I don’t think we ever sold a 35mm equipped system into the USA otherwise it would have rattled the machine to bits. The 35mm projector used the same Phillips cinema mechanism that was used on the earlier telecine systems. Here the film was driven by a Geneva mechanism (see diagram) and, as this is an interesting little bit of mechanics, I shall give a few words of description. The diagram shows the mechanism halfway through a pulldown. The pin (p) on the Driving Wheel moves the lower slotted wheel through 90 degrees each time and then the Journal Surfaces engage closely to lock the 16-toothed sprocket in position until the next pulldown. Obviously a normal 16mm projector does not need to move the film so far and the mechanism was not so complex. However we wished to stretch the capabilities to include instant start and variable projection speed.  No mechanism to achieve that existed at the time so we had to come up with something new. Two engineers were each asked to provide a proposed design. The selected design used two cams; a heart shaped one moved the claw back and forth while a surface cam moved the claw in and out of the sprocket holes.  An electro-magnet was arranged to pick the surface cam follower up at the highest position to prevent the claw from entering the film. Thus it was possible to choose when and how often the film was moved. It could run from about 1 fps to around 35 fps. This meant that the film could be held on a still frame and then started instantly. It was also possible to slightly slow motion to made news items last a bit longer. This was another useful world first.

 

We learnt a lot about projector design during this exercise. One problem is that particles of the film emulsion can embed in the gate pressure plates, making them very rough eventually. This can be remedied by “stoning” the surface with a small stone but it is best if it doesn’t happen in the first place. Hard chrome plate was tried but not with much success. I think we ended up with stainless. The edge of the film must be accurately guided to prevent it weaving from side to side. This had to be done with artificial sapphires. The film literally sawed through other materials. Another difficulty arises from the sprocket hole pitch of negative film being different to that for positive print film. The reason is that the two run over a common sprocket in the printing machine; obviously the outer one is on a larger circumference. The outer (negative) is also on a thinner part of the sprocket tooth and therefore has a smaller hole. These two points have implications in the design of the claw stroke and its thickness.

 

The first outing for the B3404 was to NAB in Washington DC. No significant union problems here but the hotel mains power supply left something to be desired. The first problem that we encountered was static charge from the nylon carpets. This had the unfortunate effect of deleting the data from the store that recorded the start and stop frame numbers for our film sequences if someone touched the control panel on the machine. It proved impossible to fix this during the exhibition and I had to resort to some very fast typing at the appropriate point. Part of our demonstration showed the ability to re-order a set of adverts. To do this both film projectors would be on and, as I was coming up to the closing slides, both slide projectors were on. At this point there was a horrible tearing noise and the film image was replaced by a blank screen. I was in the control room and could not see what the projector was doing but it was obvious that the film had been ripped up. I cut to the closing slides and my boss of the day had the task of explaining what had happened.  With all the visitors milling around there was no possibility of investigating what had happened so we abandoned the little show for the day. Once the hall had cleared we went through the routine again and everything was fine. Next morning we tried again -  rip rip! We waited until the evening but again found no fault. Next morning we were stupid enough to try again – oh dear. That evening it dawned on us; the electro-magnet that stopped the projector claw trying to run at 60fps was powered from the same supply as the projector lamps. With all four projector bulbs on the supply dropped and the magnet could hardly cope. Knowing that the hotel supply was rather poor we concluded that the supply would be even lower during the day when everyone was up and running. The spring that kept the cam follower on the cam (when not held by the magnet) was weakened. The next and last day we ran the sequence six times with no problem; wonderful!

 

 The B3404 was also fitted with a preview camera so you could set up your next film or slide.

 

That evening we packed hastily. The equipment was due in Sydney in a few days time but, more importantly; we could get to Hawaii (Oahu where Pearl Harbour is actually) for a few days rest while the telecine travelled down. We ended up at the Sheraton on Waikiki beach; excellent!

 

The above picture was taken at AWA North Ryde on the 2nd time the B3404 was demonstrated.

Both the demo sessions took place in the Bungalow at AWA ,that is why it had Patio doors fitted as that was the only way to get the Telecine in!!

In the Photo left to right are Arthur Gough Channel 7 Brisbane? Andy Fremont & Martyn Clarke, if you look closely you will notice a small Koala bear on the top of the Telecine this is Greg, he was our good luck mascot if anything went wrong he would be turned so his back was to us! he belonged to Iain Reid who was also part of the crew from Chelmsford.

 

B3404 Telecine control by the frame counter by J.H. Cox 1975 click here

 

The B3404 telecine in New Zealand by A.C. Carman 1977 click here

 

B3404 newspaper cuttings and advertisement click here

 

 

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