Learning Curve: Part 1
To Track Or Not To Track
Rob Halliday
To track or not to track… that, to paraphrase some
famous playwright, is the question…
Tracking in lighting control systems is one of those things
that many people think they understand, yet far fewer
really do – the fractional uncertainty every time they
press the record key the giveaway.
At heart, tracking is simply this: when you put a light at
a level, it stays at that level until you tell it to do
something else. The converse of which is that if you want
it to do something else – like, say, fade out at the end of
the show – you have to make sure you’ve told it to do so.
That’s actually how the earliest lighting control systems
worked. They had big levers operating mechanical dimmers.
The person running the lights would push each lever to a
level requested by the lighting designer. Eventually the
state would look nice, the LD would say ‘plot that’, the
operator – usually operators – would write down the levels
of all the levers for the first cue.
Then they’d make a second cue by moving some of the levers
to new levels. Come ‘plot that’ time, though, they’d just
write down the levels of the levers that had moved. The
others would just keep riding at the same level – they’d
‘track’ into the next cue. And so on for the rest of the
show.
The system worked well for running shows – at any given
moment, the crew only had to worry about the levers they
actually had an instruction to move – and for overlapping
cues – operator 1 could just keep moving their fader over a
one minute sunrise fade, regardless of other people doing
later cues. It worked less well when the LD needed to jump
to a cue out of sequence, since the only way to arrive at
cue 10 was to start at cue 1 and work through the
subsequent nine sets of changes. An assistant – a ‘tracker’
– would be employed to write down the changes (creating a
‘track sheet’) and, from that, figure out all the levels of
each state; when jumping to a cue they’d call out the
actual levels making up the state to the crew at the
dimmers.
In the UK, we moved away from big levers controlling
dimmers to consoles with small faders remotely controlling
the dimmers, partly so the operator could be out front and
actually see the lighting! Having small faders meant the
manufacturers could offer multiple banks of faders, or
‘presets’ (usually two, sometimes three, occasionally
more), controlling the same dimmers. Now the operator could
create cue 1 and write down all of its levels, then create
cue 2 on the next set of faders and write down all of its
levels, and so on. When running the show they’d set cue 1
and preset cue 2. On cue, they’d crossfade from cue 1 to
cue 2 and use the first set of faders to preset cue 3, then
repeat throughout the evening. It worked for complex
transitions even with large numbers of dimmers. And jumping
to any cue was easy – just set the state and fade to it.
Occasionally – on cue, a practical light turned on – it
wouldn’t be worth wasting a whole preset for the change,
with the risk of tiny level changes on other channels. In
this case the channel would just be manually added to the
active preset; the fade would be noted as a ‘move fade’ on
the cue sheet. It all worked well – unless an LD changed a
level in cue 1 and wanted to make the change in subsequent
cues – a flurry of cuesheet ammeding!
When each country moved to computer boards, they followed
their prevailing methodology of the time. American consoles
stored only the changes in each cue and relied on computing
power to figure out the actual state when jumping around
out of sequence. English consoles recorded whole states and
replayed crossfades from one to the next, with the option
to create move fades for special cases of adding a few
channels to a base state or where cues had to overlap.
Now, many consoles let you choose the behaviour your
prefer. Trouble is, tracking or not is really more than a
setup option, it’s a way of thinking. One clue: the
different ways American and British LDs (to generalise
slightly) think of ‘cue 2’: to English LDs, it’s usually
the state of cue 2, to Americans, the transition from cue 1
to cue 2 – they’re almost more interested in what’s
changing than in the states themselves. Tracking makes the
changes important.
On small shows with just a few cues, it really doesn’t
matter which approach you take. With complex shows,
tracking usually wins: want to make the same changes to
cues 1 through 10? Just change cue 1, and the subsequent
cues will also have be right, rather than having to make
the same changes over and over again. Or, with moving
lights, change the position and have it stay there rather
than wandering back to where it used to be as the next cue
runs.
Of course, with great power comes great danger. You can
make a mess of cues much more quickly in a tracking console
than a non-tracking one. To avoid that you have to really
get it, and the only way to really get it is to try it,
make mistakes – then figure out what happened and how to
fix it. Do it a few times and a mental light bulb will come
on above your head as suddenly, it all just makes sense.
There are a whole lot of other words consoles now add
around this subject – more on those another time. For now,
just remember that the light will keep doing its thing
until you tell it to do something else. So, critically,
tell all the lights, even those that aren’t on, to go to
zero in the final blackout cue. That way when you
subsequently add lights something will tell them to turn
off, saving the embarrassment of ruining the end of the
show…
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