Broadcast Telecine; Rank Cintel MK III

My career was with the older "twin-lens" machines "down the line" - you may wish to look those up. I spent a Sunday afternoon in TK¹ on my TA² Circus lining up a machine and then playing out a feature film to Network. IIRC the Mk. III uses a line-array CCD rather than three PECs³ as the sensor.

There is some discussion about "flying spot" scanners in relation to Test Card F other at the "other place".

In later years TK machines weren't used for direct network transmission but films were TARIFed (I'll leave that one for the reader) and recorded onto VT for subsequent transmission.

1. TeleKinematograph. Also avoided confusion with TC being the building code for Television Centre, TVC being a later incarnation (but not one I will use).
2. Technical Assistant. Someone who came into the job but didn't have a relevant degree so had a longer training course over two years with on-the-job training in between. Like me.
3. Photo-Electric Cell. However, they were in fact electron multipliers in this application.

You may also find this of interest:

I heard that sometimes telecines needed close attention, and sometimes would have problems while being live to air.  There is a You Tube compilation of off air recordings of technical breakdowns, including a few telecine related issues.  One being a film snapping during a broadcast of Star Trek!

@cathovisor I think my friend David has one of the PM tubes from one of these machines. He's a BBC continuity announcer and newsreader on radio mainly. He *may* also feature on Doz' Television Workshop 😉

Posted by: @crustytv

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Interesting to note that the test card C used, is one specific telecine line up, which also includes 405 & 625 frequency gratings, not seen that one before.

😉

@wayned 

There were still a couple of these line-up films in the  "Betacam maintenance room" at BH in Cardiff, I wish I'd salvaged them before they ended up on the skip.

Posted by: @mfd70

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@wayned 

There were still a couple of these line-up films in the  "Betacam maintenance room" at BH in Cardiff, I wish I'd salvaged them before they ended up on the skip.

This was at the beginning of a file that had been digitised from a Betacam tape that was originally on film!

Hi All, Now you are on one of my favourite subjects TK. I joined the BBC as a TA and having done my "A" course at Wood Norton BBC Training Centre I was posted to Television Centre into the TK department. There where in excess of 35 telecine machines in the department then including those at Lime Grove which were mainly used for Nation Wide which we had to man. The majority of these machines where Mk1 and Mk2 Rank Cintel machines. The Mk1's where mainly 35mm. The Mk1's had been modified to solid state and colour, the Mk2's being solid state. These machines where all CRT with Photo multipliers and and used a claw film pull down mechanism to pull the film through a frame at a time. This was quite a noisy process hence you shut the door when running. You had to be careful when loading the film as it had to be threaded frame accurate across several film cogs in order to run. The Mk 1's where metallic bronze and the Mk2's where a dull blue in colour but work the same way and had the same mechanical arrangement. I could load one of these machines in about 25 seconds. They would only play forward or reverse (X1). We also had a 16mm and 35mm polygon machines Mk1's in both cases and these had a circle of prism's so you could run film at variable speed, optically of course. The newer machines where "Hopping Patch" machines which was the introduction of the Mk3's and where fully analogue then and had a proper capstan as in the Mk3 C's shown in the film. You could fast spool these just like a VTR. These gave superb pictures so long as you got the two patches perfect which took a bit of doing! You had two crt patches scanning the film as the film motion was continuous the first patch did field one and the second field two. The new kid on the block was the Mk3C (MKIIIC). later becoming the Mk3 422 SDI out of the store. I will come back to these in part 2. Much to tell.

Hi All, Part 2. A lot of the Mk1 35mm machines where in pairs for running full feature films. Each reel would last 20 minuets so you loaded the first reel on machine 1 and the second on machine 2. When you prepared the film you stuck a bit of silver foil on the edge of the film where you also found the cue dot, these were little circles stamped in a few film frames 8 seconds before the end of the reel, you may have seen these? this is so you can start the second machine with reel 2 as it would take 8 seconds to run up to speed, the film sync cross leader allowing for this and the switch taking place then to produce a perfect switch over. The silver foil would be detected as it came to the end of the reel and auto start the second machine, you had to be ready to start the second machine in case this failed or the silver foil came off. Now it has been explained that you needed to tarif the film to correct the colour in some cases of each shot. A second engineer would be doing the colour correction in another booth in the case of the BBC, unique to them, you had two joy sticks, one for black level and one for gain. You turn the controls for master lift or gain and moved the joysticks to change the black level colour are make the whites correct with the gain joystick. In all other companies I have worked for you had three joystick controls to do Lift (Blacks) Gain (Whites) and Gamma (Light Curve). The controls where marked with R, G and B which is where you moved the control dependant on what you wanted to correct. Back to the dual TK machines you would be fully occupied getting each reel ready and loaded. Some feature films could have up to 7 reels. All film then had to be transmitted live! as copying to VTR was not allowed as it would be a generation degradation to the quality unless it was a bad piece that was so bad to tarif live would have been difficult. I have to say the best 35mm film I used to see was Dallas, it being pin sharp, low grain and almost perfect colour and exposure, always impressed me! The audio on film could be Common Optical, Sound track down the side of the film frames, normally stereo on 35mm and mono on 16mm or Common Mag on 16mm or Separate Magnetic tracks that you loaded on to a sound follower. This was also 35mm sized or 16mm and had sprockets just like the film it came with. The Mk1 & 2 TK's used Selsyn locking to lock to the TK machine. Can tell a few stories on that! Common Optical had a slit of focused light shone through the film and was picked up by a sensor under the film.

When I left the BBC and joined Thames Television they had seven TK machines at Euston and two at Teddington. Most Rank Cintel Mk2's but they also had a Marconi TK which was unusual for its age as it could run 16 and 35mm film. They had one Mk3 which they ran commercials off like Corn Fakes as Kellogg's insisted these where first generation so came directly off TK as did the Thames ident. The engineers that drove these did there own maintenance, it would only be unusual faults that took a bit of solving that I would get called to. When the VTR department was rebuilt at Euston the TK machines where reduced to two, these being the newer Mk111C's. There where two engineers, Kevin and myself that would look after the maintenance of these and change the tubes when necessary. These machines where complex to say the least. They had a digital Y, B-Y, R-Y store but where still analogue at the front end. There reason for the store was the machines could be sold to the states as they could do, with modification, 525-30 and 625-50. The store gave this ability, but in my opinion the hoping patch machine did a slightly better job. The earlier TK machines scanned the film with the tube running in 625 line. The new Mk111C's scanned the film at 820 lines. This was written into the store like this and the complex side being the read cycle which was complicated as it could read out in 525 or 625. Something to get your head around. I will come back to these machines in a bit more detail in Part 3.

I remember watch a screening of Le Mans in the 1990s where the operated switched over the telecines a little too early & I was treated to a few seconds of a countdown clock before the action resumed!

Hi All, now for Part 3. With the introduction of the new MkIIIC's to Thames Euston they where a level more complicated than the previous Mk1 and Mk2 machines. As people where having a few problems trying to get them working correctly I was dispatched to Rank Cintel on a three week course. This wasn't so bad as Rank Cintel where located in Ware Herts where I lived. This was in the mid 80's and on courses then you went through all the electronics to component level. Now think about what the machine is trying to do? You have a tube in the machine that has to be positioned correctly in relation to the gate and film. It has to be mechanically set in the correct position, the electron beam has to be centred to the dead centre of the tube, using a thing called focus rock, you have to get the raster correct, height, width and H and V position. and this has to be correct to the film gate for both the 35mm and 16mm gates. Tied in with this is the capstan phase!! and the castellation led sensors in relation to the film sprockets. On the Mk3 there is only one film sprocket roller where the film exits the gate. A standard machine has one operational raster control called PAN for panning full height 16 X 9 or CinemaScope film. To get the electronic scans right you had to make the machine standard with just the PAN function. All the machines I have looked after have always had the ZOOM option fitted which enabled you to zoom in or out of the picture and PAN up & down and side to side. I have seen many an engineer loosing his head over this. I could set it up in about 20 minuets so long as the standard machine scanning had not be interfered with! If it had I would be on it for about 2 hours. Tube changes where complicated but the last three machines under my care where only maintained by me and I could do a tube change in two hours. The Zoom board is what the operator in the first film is referring to about the special BBC mod. We did the same mod on our machines to switch between 4 X 3 and 16 X 9 3 years before the BBC!

I hope you can see now the items that have to be correct, tube mechanical position, tube electrical centre, tube scanning, film gate to film sprocket position, mechanical and electrical, and then the Zoom board operation. On top of this you have the film mechanical focus to take care of. Do one thing incorrectly and you will never get it working correctly. When I left Thames to join BSB/SKY it was my Telecine and 1/2 inch tape knowledge they where after. There is also the common optical audio to take care of. These where two 6 volt lamps facing the capstan, one for 16mm and one for 35mm com opt. The large capstan had two groves in its circumference to mount the two audio pickup sensors which where held in position by two long thin arms under the film. The sensors had to be within the capstan diameter as this is where the sound is in sync with picture. The lamps when changed had to be set up to get the filament lined up with the optical slit and focused on the sound track. This could be a variable aperture or variable density track. Variable area worked best, there was more distortion on variable density sound tracks. The 35mm pickup was stereo.

The Sky TK machines where special as they had RGB high definition digital stores running at 80Mhz sampling. If you think about the standard Mk3C's scanning the film at 820 lines somewhat faster than 625 line the analogue RGB chains had to have a bandwidth of more than 5.75Mhz it being just over 7Mhz. Our machines used this and ran the raster at 625 line so that gave you nearly 7.5Mhz video response. The output was recorded on special modified Betacam SP machines these being WBR-700's so they could record this wide band signal. We would record a 16 X 9 signal off the TK into the WBR's It meant we could then take a 4 X 3 picture from the 16 X 9 recoding without losing resolution. 

Just to go into some more detail on the Mk3C's if you where running 16 X 9 and adjusted your Zoom control so you got the full film height and width due to the movement of the film your CRT raster would be a single line!! 625 lines all in the same place, the scanning being done solely by the film motion. This was indeed normal but built into the frame scanning was a thing called slow scan. This moved the raster across the CRT faceplate taking seconds to do the movement and the phase of the capstan was moved in line with this so the scanning look correct off the film but stopped the tube burning. In the first video he shows you the CRT raster, just above this is a burn PEC. This produces a level corresponding to the brightness coming off the CRT faceplate. In other words burnt areas of the tube would give a lower light output. This was added back in the RGB channels which corrected for CRT burn. Another complicated setup to carry out but it gave you a much extended tube life. We used Brimmar Tubes and these where £5500 each.

Due to consumer CRTs not having a linear voltage to light output broadcast gear had to apply the "gamma" correction to make the CRT's look correct, this being done in the Cameras and Telecine machines and the variance with film density and sensitivity this has to be set in the TK machine channels too. I have only just touched on the complication of these machines but I have loved looking after these in my broadcast career for many years

Hope you enjoyed this, I could go into much more detail but I'll let you off.

Adrian

Hmmmm..... not quite enough room in the workshop, though tempting?

https://www.broadcaststore.com/store/model_eq_list.cfm?intModelID=5389&bitCompare=1

p.s. I note P.O.A  I bet they are scary prices.

Seriously though, Adrian, many thanks for the enlightening and fascinating three-part post. Quite a remarkable leap from consumer TV servicing to broadcasting, halcyon days for you and many, I think.

Hi All, Thanks for your kind note there Chris. I thought I had better add Part 4. I have mentioned everything to do with the light source, the CRT but what happens after? The CRT face is one point of focus the other being the film itself. After the light has passed through the film it enters a rather large box where the PEC's reside. Photo Electric Cells which are actually Photo Multipliers. This is very similar to a three tube cameras dichroic mirrors and prisms, it is the same in the light box but somewhat bigger, in the video it sits behind the "4 2 2" plate, it is a large item and goes quite deep into the machine and completely sealed against light except what has passed through the gate. The photons are split via the dichroic filters and prisms arriving at each Red, Green and Blue Photo Multiplier. These are multi anode (dynodes) devices so photons enter the device hitting the photocathode which then releases electrons which are then focused onto the 1st dynode which when hit by electrons releases more secondary electrons. There are many of these dynodes (anodes) which do the same so you get a nice gain by the time you reach the the final anode. The dynodes and are all connected in series by a number of resistors so you have a potential of 50-100 volts between each dynode up to the final anode were there is an FET amplifier. The final anode will be operating at about 700 volts. In the film he is adjusting the gain for 700mV with an open gate. The adjustment he is carrying out will be the gain off the photo multiplier by adjusting the final anode voltage. You do this by setting the green at 700mV and then differentially adding red and then blue and adjusting for "0" so the gains are then perfect, the waveform monitor will be set to X10 gain so you will see any difference immediately. After this the Red Green and Blue signals will go through their respective "afterglow" correctors and then the gamma correction amplifiers, correcting for the film and the viewers display CRT.

When we got the MkIIIC's at Thames it was a bit of a struggle getting them correct hence being sent on the course. I like to get hands on before a course then you are armed with the correct questions and procedures you need to know! Cintel brought out the URSA Telecine after this, much the same but with some enhancements on the Mk3 but still based on the Mk3 and yes still using a CRT. After this came the CCD line array telecines, again three CCDs. Somewhat simpler in operation with a light source on the film as the film was driven over the CCD's this being digitised and read into a store. The store is where you did all your correction. The modified down HD machines we bought at Sky where £250,000 a piece so not cheep. In the 70's you pay that for a 2" cassette based commercial machine. These were Ampex ACR25's and could lock an run in about 400mS or better. 2" quadruplex machine would normally take up to 10 seconds to lock. Yes these were special 2 inch quadraplex machines with vacuum coulombs, vacuum capstan and guides. Two of these transports per machine, a 24 cassette carousel driven by a 1/2 horse power motor, reel motors and trombone cassette loading unit in one cabinet the second cabinet housing all the control electronics, most being TTL IC's. When you turned these on they pulled 100A then dropping to 25A. Take a look at Youtube, these are a beast and Thames had four of them. Spent many hours fixing these.

Enjoy