In the third part of Angus C Clarke’s overview of film, stage and television
lighting, he looks at some of the ways in which the technology has changed over
the years.
The TV Industry in general has, over the past 30 years, undergone many
changes, but the one that has affected lighting the most was the change from
tube-based cameras to CCD (Charge Coupled Device) based pick-up devices in
cameras.
In later years, the CMOS- (Complementary metal-oxide-semiconductor) has also
been used with much success. These devices have far increased sensitivity and
the result of the increased sensitivity of these receptors meant that the level of
light required to excite the photons in the solid state unit to generate good
pictures, decreased dramatically.
Lighting and power
In the early years in TV, with studio lighting having to satisfy light-hungry camera
tubes, the major problems encountered were in dealing with the control of heat
being emitted from studio lights. Most people are aware that incandescent lights
get extremely hot and as such are far better heaters than lights. For every R1.00
of power consumed by these lights, only 11 per cent is made up by visible light.
The rest is re-distributed as heat. So with as many as 50 x 5kw and 2.5kw lights
being used, almost at full power, the heat build-up was massive. While vast
amounts of power were being used to power lights, more was in turn required
to re-cool the studios, via massive air-conditioning units. So, for every kilowatt of
power consumed to generate light (and heat) another kilowatt was required to
power the air-con units to cool the studio down.
Limitations
Added to this, a phenomenon known as video noise plagued us at every turn.
This is when the picture battled to display any detail in a dark area but rather
displayed a jumble of pixelated picture information or alternatively, lag –
whereby any bright spot, such as a light or mirror reflection that the camera
panned through, left a comet-tail of highlights dragging behind it, often
remaining on the screen for many minutes after the bright source had
disappeared. This meant that the camera could not be used until the tubes had
recovered, resulting in unscheduled tea-breaks during production.
Careful lighting control important
This era was however a magnificent training ground as it taught us about light
control and balance, and that more was not necessarily better. We learnt very
quickly that you could not use colours that were too light for costumes and sets
and that controlling the light spill was supremely important. Whites and sheens
were taboo and caused major problems in the picture composition. If you did not
carefully manage the excesses of light spillage, lights that were not necessarily
part of a specific scene could cause many unintended problems.
Technology changes
With the advent of CCD technology, the camera’s optimum sensitivity of 2000 lux
(lux being the unit of measurement for illuminance) at ƒ4 in the 1970s and 1980s
jumped to 2000 lux at ƒ5.6. This meant that the camera could be excited by 50
per cent less light to achieve the same picture quality. This started a drive to use
smaller lighting sources to achieve the same result.
In addition, the development of alternative light sources was being examined
and in the early 90s experiments were being conducted in using fluorescent
technology as a lighting source. However, the base materials used in the “florrie’
environment in conjunction with mercury, caused these lights to produce a
greenish hue which gave faces a very weird colour. This was unacceptable for
the sensitive TV camera system as, psychologically, a green face indicated either
a person being sick or being a Martian. Great if you were doing a science-fiction
programme but hopeless if you were presenting news.
Many hours of research were conducted, using alternative methods of producing
a lower power but higher lumen output type of light that could be used in film
and TV.
Technological improvements
As time and research have progressed, so has the quality of the CCD and CMOS
and, with this improvement in receptor quality, the light-level requirement has
also dropped. The advent of the HD-CCD has been one of the biggest steps in
the technology evolution as the light level required to generate good static
picture quality has dropped down to a quarter of what it was 20 years ago.
Concurrent with the CCD development, the realm of TV lighting has undergone
many changes over the past 30 years. Initially the 2kw Fresnel spot replaced the
5kw unit as the studio workhorse for the main lighting level setter.
In fact, many 5kw spot lights have been adapted to hold the 2kw CP 41/73
bubble, immediately bringing about a halving of the power output. We could
have resorted to dimming lights to reduce the output, but by doing that, we
would bring the lights’ colour temperature down to an unacceptably low level.
This would engender a red cast over all the talent. Changing the actual source
was a better way to reduce light level, as the colour temperature could be
maintained as an acceptable level.
Another point in this regard is that the larger light surface from the light source
covers a larger floor area, meaning a large area of movement can be covered
evenly.
With the new LED technology, the big advantage is that there is a reduction in
the physical size of some lights. As it’s a new technology, it is still undergoing
ongoing development as more efficient ways of applying the technology is being
further researched.
