Cue Dots

I know we have cue dot discussions semi-regularly here and I haven't seen one (a discussion ) for a while, since 2014 according to the search

Spotted on a very old episode of Rainbow, skip to 17:02 (warning, scary looking Bungle alert):


Notice a rather fat looking cue dot top right at 17:02. It appears to be two dots one on top of the other slightly off-set and its rolling bottom right to top left. At the cut to black the dot is suddenly rolling slower in the opposite direction. On the Thames end-cap two cue dots actually disappear at 17:42 one after the other.

I think we established in previous threads on these things why they roll the way they do, though I'm perplexed as to why there appear to be two cue dots here, unless it's the way it was added/generated, and as to why the rotating direction changes with the cut, though that may simply be the credits for that episode were redone for whatever reason. I'm sure somebody here said cue dots weren't added at production stage but added later, though that wouldn't explain why they change direction instantly in this case.

This doesn't appear to be an off-air recording, so it does seem there were two cue dots on the tape.

It wasn't uncommon to see two cue dots - but one was normally generated live. Sometimes there'd be a cue dot on the tape, disappearing 5 seconds or so before the end of the programme, and another added live by the company playing it out if they were networking a promo or publication anno after the programme (eg. 'a Rainbow cassette is available' or 'Emmerdale Farm paperbacks are available'). The second cue dot would disappear 5 seconds before the end of the promo/anno - as that was the real cue for the regions.

Thanks Si-Co

I presume the cue dot added live would typically sit on top of the one on the tape so the end picture would only be one cue dot.

Not really! Cue dots weren't always the same size (or shape!) so didn't necessarily sit on top of each other neatly. I've seen quite a few examples where you can clearly see the two dots simultaneously.

Sometimes a programme was re-edited after the original production cue dot had been inserted, and when that happened a second dot was sometimes overlaid. While we're on the subject, programmes sometimes had a commercial break edited out so a cue dot would appear in the middle of a programme then suddenly vanish. This information was always contained on the TX form provided with the transmission tape. If a cue dot appeared unexpectedly by mistake, the network playout company would add another one and keep it there until they had used the red phone to tell everyone to ignore it!

I was going to say, that first episode of Rainbow looks a bit remastered in a way - I can't quite put my finger on it but I'm pretty sure I've seen another early episode where the credits aren't as clear or dynamic as that.

I'm not entirely convinced that is two dots to be honest (in the specific case of the Rainbow clip above). It looks more like an artefact of the technology used to key the dot onto the video to me. The 'two' dots are in sync with each other visually (appearing immediately at the point where the camera switches to Bungle) and disappear within a frame.

I agree, the movement on the 'ghost' cue dot is in exact synchronisation with the 'main' image. It could well
be a de-interlacing artefact of the You Tube upload process. The delay between the two apparent cue dots vanishing is likely to be a field (half a frame) .

That's not to say double cue dots didn't happen, they did (and still do !)

I think you've hit the nail on the head there. The spec for the (ITV) cue dot was quite lax with regard to the positioning and the frequency of the moving stripe (it didn't have to be moving at all if you didn't want it to). The generator for generating the stripe was deliberately set so that it was just a shade off of a multiple of line frequency - it could be slightly higher or lower, but it ensured the stripe moved within the dot and was therefore visually eye catching which was the intention. It was quite possible at the time for the stripe to move in one direction, slow down to a standstill, then move in the other direction. No two generators would be same, and certainly not any any given moment in time. The chances or two independent cue dots overlaying each other and the moving stripes being in sync are, well, extraordinary. So as you say, I suspect it was just a video keying artefact or some sort.

Those of us who were a little bit sad (ahem), could tell the originating station from the dot a lot of the time. Anglia and TVS used a non-moving two vertical lines (TVS's was bigger), Granada's was slightly edged in to the left (not exactly in the corner), Central's was huge and moved quickly, Tyne Tees's was exactly square and the diagonal stripe moved at a fairly slow, constant rate, Thames's changed speed and direction etc etc.

Do I win the prize for biggest anorak on this forum?

Also I've seen cue dots on some very old American shows recorded live at the time. They tended to just be a single, fairly large square and flashed 3-5 times about 10 seconds before the break, quite clearly someone literally hitting a button on the mixer a few times to bring it up.

Looking at that Rainbow clip, surely the most important question is, what's the point in flashing a cue dot up the second the presenter has just said goodbye?