LUU BACKSTAGE BEGINNER'S GUIDE TO LIGHTING General Theatre Safety

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26 Νοε 2013 (πριν από 3 χρόνια και 4 μήνες)

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LUU BACKSTAGE
BEGINNER'S GUIDE TO LIGHTING


General Theatre Safety

A theatre can be a dangerous space!

During preproduction week
and a show
there may be people working overhead, live
cables may be present in unexpected places and many slip and trip hazards

may exist.


Make sure you are aware of people working around you at all times, and take care!


Some items of equipment in the theatre require special training before use


these include
the scaffolding tower
, flyrail

and the power control equipment.

If in

doubt, ask!


The Riley Smith Hall

General

The Riley is a proscenium arch style thea
tre, 26 feet (
8m
)

deep
by 36 feet (11m) wide
with a
23 foot (
7m
)

by 14 foot (4.27m)
high
opening

in the arch.

Side legs provide sight line adjustment stage left and stage r
ight.


A 26 foot (7.9m) high flying tower is provided with
3 flybars
,

each rated at 120kg inc.
bar.

We recommend that no more than 50kg is hung on each bar, as it gets very difficult
to fly much more.


A full dual
-
channel cans system is installed, with be
ltpacks and movable base station.


Sound is provided by a

2k Bose PA

System, 32 channel Multicore, and
24 channel
Soundcraft mixer
. Various players and EQs are available for this system.


Lighting

Power is supplied by a 3
-
phase 125A supply. Normally only t
he Chief Electrician
(Chief
LX)
will have access to the power bay where the isolator and trips are situated.


4 lighting bars are rigged above the stage, numbered LX1 (downstage) to LX4 (upstage)
.

These are rated at 200kg each.

Front of house

a U shape rig

is hung
, and a truss
with 3 socapex cables for power is
available
.

This

m
ay be hung as temporary rigging from the exposed concrete beam.


84 channels of dimming are available at 2.4 kW per channel.

This is broken out to a patch panel in the patch bay abo
ve stage left.


Control
is provided by DMX
512

from a Celco Explorer

lighting d
esk, which provides 96
Highest
-
Ta
kes
-
P
recedence
(HTP)
channels
for normal lighting control
and 24 Latest
-
Takes
-
Precedence
(LTP)
channels for intelligent lighting control.

(The in
struction manual for this desk can be found at
http://www.celco.co.uk/
)


Types of Light

L
ighting
fixture
s group into families and
each family gives different variations
of beam
size, beam shape, and beam quality.


Floods

The beam size, shape and quality em
itted by a flood is fixed: there are no adjusting
knobs. The light is therefore suitable for lighting skies and cloths. It is not selective
enough for lighting actors. Some units may be single or grouped in 3s or 4s for colour
mixing.



Soft Spots

Prism Co
nvex (PC) spots allow control of the beam size, and the beam may be roughly
shaped by a rotatable barndoor. The quality is even and soft
-
edged, with less light
-
spill
outside the main beam than in the case of a fresnel. In addition to the PC’s, Fresnels hav
e
a very soft edge. The beam angle is adjustable and its shape roughly containable by a 4
-
leaf rotatable barndoor. The extent of the spill outside the main beam makes them
unsuitable for longer throws, particularly from the auditorium.


Profile Spots

Profi
le spots give precise control of the beam. An iris diaphragm (for round edges) and
shutters (for hard edges) can produce shapes in all sizes. For more complex shapes,
special masks can be cut. Edge quality can be adjusted from very soft to very hard by
mov
ing the lens, while a metal pattern plate called a gobo can texture the quality of the
whole beam. The number in the profile's name indicates the beam angle.

Whereas standard profile spots have a fixed beam angle, which is narrowed by shuttering,
variable
beam profiles use a pair of lenses whose differential movement gives a wide
range of beam angles and edge qualities. The shutters are then only required for shaping.
Adjustments are faster and more efficient use is made of the lamp's output The number in
a

variable profile's name indicates the range of available angles.


Beamlights

Most lighting instruments produce a conical beam so that the spread widens as the throw
increases. Beamlights use a parabolic reflector (and no lens) to produce a near parallel
b
eam which is more intense than a lens spotlight of the same wattage. This is one of the
more important developments of the past decade. The optics are fully contained within
the glass envelope of the lamp. Various Lamps providing angles of a squashed near
-
parallel beam are available. The intensity produces a depth
-
enhancing haze in the air, so
intense that it is effective even with deep colours. The basis of most rock lighting today.


PARcans
are a cheap and cheerful kind of beamlight, which we have a lot o
f!
Gel

Gel is an archaic term for the coloured sheets of plastic placed in the front of lighting
fixtures to change the colour. Some venues refer to it as a “Filter”, but we like gel.


For nearly all shows, two main colours will be used


these will usual
ly be referred to as
“Cold” and “Warm”


cold is blue, warm is usually a straw (pale yellow)


Available in several hundred different colours, gel can be very confusing!

To help with this, all gel colours have a number and a name.


For example, two gel ofte
n used for a warm wash in the Riley are:

009


Pale Amber Gold

103
-

Straw


As there are many very similar colours, when cutting gel to fit into lights it is
recommended that you write the number on the gel with a chinagraph pencil or
permanent marker.


Ch
oice of gel is down to the lighting designer

(LD)
, and these will be noted on the
lighting design.


Gel is mounted into lights using a gelframe


this is a piece of metal or heat
-
resistant card
with a slot in it to fit the gel into. They come in many diff
erent types, so be sure you’ve
got the right one for the light


if you’re not sure, ask the Chief LX or LD!


When cutting gel, use a sharp knife on a wooden surface or a sharp pair of scissors. It’s
easiest to cut around a gelframe for the light you’re m
aking it for, as that will make sure
you get it the right size.

For the Coda series and other powerful floods, the gel should be cut ½” to 1”

larger than
the frame as it will shrink under the heat.


Rigging

Rigging is one of the most important aspects of
safety in a theatre.

If you get this wrong you may end up
seriously
injuring or
even
killing members of the
public, which is infinitely worse than mere cast or crew.


To rig a light safely:

1)

Ensure all parts of the lighting fixture are secured to the light,

and the light is the
right way up


gelframes and barn doors can fall out of upside down lights!

(If anything looks broken, check with the Chief LX.)


2)

Hang the light onto its bar or truss using the hookclamp.


3)

Clip the safety chain around the yoke or the
safety chain point(s) on the light, and
around the lighting bar or truss.


4)

Tighten the hookclamp screw.


5)

Check that the rotate (left/right) screw is loose enough to allow the light to be
moved easily, but tight enough to prevent the light wobbling.


6)

Check
that the up/down locking knob(s) are reasonably tight, but loose enough
that you can undo it one handed.


7)

Plug the light into the relevant socket(s)


often the LD won’t have told you
which socket (s)he wants each light in, so decide yourself

and make a no
te on the
plan.


8)

If necessary, tidy the cable up on the bar using LX tape. There should be enough
to allow free movement of the light, but never allow a cable to sit directly in the
beam of a light.


No light should ever be rigged to light
anything

closer

than about 2
-
3 feet due to the
possibility of fire
.


Patching

Patching is plugging all the lights in the rig into the dimmers so they can be controlled.

The LD may have produced a patch plan, but the basic guidelines are simple:


1)

Never patch live


ie wit
h the power on.

2)

Be careful not to touch the pins on the plugs.

3)

Never put two or more different phases down the same multicore cable (Socapex
in the Riley), or on the same lighting bar. (The FOH “U” is all the same bar)

4)

Make a note of what is plugged in whe
re!


Remember that you are connecting to a
3
-
phase electricity supply


it’s much bigger than at home!


Dimmers

Dimmers are electronic devices that control the amount of electrical power passed to the
lights. The ones in the Riley are controlled by a DMX5
12 digital signal, and can be
programmed to give different dimming curves.

The most useful curves are:

Tungsten, where the curve is adjusted for near
-
linear brightness of normal lamps.

Switching, where the dimmers become remotely
-
controlled on/off switches
.


Lighting Desk Operation

The lighting desk in the Riley is a Celco Explorer.

It has 96 HTP channels for normal lights and 24 LTP channels for intelligent lights.


The components of the desk are:

Monitor





Shows what’s happening.

96 Channel faders




C
ontrols the level of the channel.

48 ”Flash” buttons




Allows you to flash a channel.

12 Sub
-
Master faders




Stores lighting states, known as “Cues”

2 Wheels





Used to alter Cue/Sub Master pages and for input.

Memory system




Used for programming sho
ws.

1 Stack fader/ “Go” button



Used for running programmed shows.

Sequence controller




Used for running chases.

2 Preset Masters




Controls overall level of channel faders.

1 Grand Master




C
ontrols the overall level.


The desk also includes the abil
ity to soft patch (patch inside the lighting desk) and alter a
few other
internal settings, such as using dual
-
preset mode.

These extra features

are
accessed through the right
-
hand

LCD, soft buttons and wheel.


To store a cue:

Set up the state required usi
ng the channel faders, ensure that the cue page is correct, pull
the relevant sub
-
master below 0%, and hit the Record button.

Cues can be named using the keyboard while the submaster is pulled, but no changes will
be made to the stored levels without hitti
ng Record.


Once that has been done for all the cues, the show could be run by crossfading the
submasters in turn. Obviously that’s a bit fiddly and prone to mistakes, so the desk
allows you to stack the cues up so they run in order using only one fader,
or just one
button!


To create a stack,
navigate the main menu using the soft buttons to [Store] > [Stack],
adjust the stack number and start cue number to the correct values, then hit [Make]

100 cues will then be added automatically in order, starting wit
h the first one.


For further information:

See the Celco Explorer manual, which can be downloaded from
www.celco.co.uk

Or ask! We are always happy to help.