GAM Pattern User Manual
GAM Product #PM101
Rosco Product # 250 8010 10660
burn from the concentration of heat on the surface. This
concentration at the gate is inherent in the optical design
of the ellipsoidal spotlight. Some fixtures are designed
“hotter” than others and therefore are harder on the
patterns used in them. It is important to have your ellipsoidal spotlight cleaned and aligned for projecting images.
A little maintenance will greatly improve the quality of the
images and extend the life of the pattern.
Patterns #319 Circles, #258 Daisy Pattern & #387 Concept 1
projected in Purescape retail store
PRODUCT INSTRUCTIONS
GAM strives to see that every gobo pattern you receive
meets exacting quality standards. GAM inspects each
and every pattern before it is sold. GAM also has an ongoing research program to insure that the best possible
materials; the steel, the chemicals used for the etching
process, and the best possible etching equipment are
used in the manufacture of GAM Gobo Patterns.
The design area should be free of nicks and scratches.
The pattern is only one aspect of getting the best image.
The type of pattern holder is also important. Heat plays
a critical role in the performance of a pattern. You want
to dissipate the heat from the pattern. The best type of
pattern holder is the ‘sandwich style’ holder, which firmly grips the pattern all around the design and aids in
heat dissipation. The faster heat is drawn away from the
pattern the longer it will last. The ‘sandwich style’ pattern
holder also precludes accidental dropping of the pattern
into the gate of the fixture during insertion and removal.
It also aids in maintaining a uniform focus.
The life of a pattern and the quality of the image are
dependent on the pattern itself and on the fixture used to
project the image. Stainless steel patterns can warp and
You will need to take the ellipsoidal spotlights apart to
clean the lenses and then you will need to optically align
the lamp. Every make and model of ellipsoidal is different. If you are not sure how to do this, check with the
manufacturer of the ellipsoidal or the local stage lighting dealer. One of those two sources should be able to
provide the needed information. In order to get the best
possible image and extend the life of your patterns, three
tasks need to be performed.
Clean the lenses, clean the reflector and finally, the lamp
(bulb) needs to be optically aligned. These three steps
will greatly enhance the quality of the image and extend
the life of your patterns. All of us have looked into the
lens of a light and asked ourselves “is there a frost gel
in that light”? In most cases, it is likely that the lens is just
dirty. The first step is to remove the lens barrel from the
fixture. Be careful to keep track of the knob when you
remove it. Try putting it back in the lens barrel if possible.
If that is not possible, make sure you put the knob in a
safe place. Replacement knobs can be hard to find.
Once you have the lens barrel out, take out the lenses. Make sure to keep track of where each lens goes
and how each is oriented. You will greatly affect the
output from the ellipsoidal if you put a lens in the wrong
place or the wrong orientation. Now, clean the lenses.
Some lenses have a coating on them, so only use clean
distilled water and a soft lint free cloth. Before you put
the lenses back in the lens barrel, make sure that the
lenses are truly clean, free of fingerprints, and are in the
correct place and orientation.
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A
D
B
C
E
F
G
H
J
A
I
Socket
Lamp
B
Reflector
C
Gate
D
Framing Shutters
E
Pattern Holder - Place Pattern
F
Focal Point - Rays of reflected light
G
converge here
H
Plano Convex Lenses
I
Lens Focusing Knob
J
Color Frame Holder
Now the reflector needs to be cleaned. With the lens barrel and lenses removed, open up the fixture to get easy access
to the reflector. It is important to remove the lamp (bulb) from the fixture. This makes it easier and safer to clean the reflector. When cleaning the reflector, try using compressed air to remove the surface dust. It is the safest method and minimizes the chances of damaging the reflector. However, if the reflector is very dirty, the surface dirt needs to be removed.
There are two ways to achieve this. The first method is to use a soft bristled paint brush. Make sure to use a new, clean,
soft bristled paint brush to clean reflectors. It is imperative not to scratch or leave residue on the reflector. If the brush does
not work use a clean, lint-free, damp cloth. Dampen the cloth with distilled water only to avoid leaving residue.
Once the lenses and the reflector are clean, the light can be reassembled. The last and most important step is to optically
align the lamp. Lamp alignment is the single most important factor in extending pattern life. When an ellipsoidal spotlight
is used to light actors, the lamp is often adjusted to produce a hot center and a feathered edge. When using the same
fixture to project an image, it is preferable to back the lamp out of the reflector until the field of light is even all the way
across, with no ‘hot spot’. With an even field, the heat is distributed over the whole surface of the pattern, rather than
concentrated on one part. In addition, the even field allows for a more uniform focus.
Most ellipsoidals have screws and/or knobs and socket mounting plates to align the lamps. First, center the lamp
filament in the field of light. Then, adjust penetration into the reflector. Consult the fixture’s manufacturer instructions for
more details. It is easiest to align an ellipsoidal when it is down and on a dimmer at a lower intensity. The fixture should
be focused on a flat white surface. Aligning a lamp can be a difficult process, but is worth the time; it will extend the life
of the pattern and improve the quality of the image. If the ellipsoidal has been properly cleaned and aligned, it is ready
to project your image. A little bit of work on the ground will reap great rewards when the image is focused on the stage.
ELLIPSOIDAL SPOTLIGHT
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