Projecting Wonderful Images Onto Your Stage
Can I project the wonderful designs available as Gobos using the lighting equipment in my hall? Joakim Odlander from Gobotech explains.
The gobo itself is an image slide that can be made out of various materials. Years ago I made a very effective star pattern by using an aluminium can and a nail to punch small holes in it, then slotted the aluminium into the gobo slot. That was a simple home made gobo.
There are, however, thousands of standard patterns of trees, leaves and anything else you can think of, that are cheap to purchase and can have great effect on a stage such as a leaf breakup used to give soft dappled lighting.
A basic gobo is made as a steel stencil. The limitation is that the stencil image has to be designed to hold together in some way; as an example the letter O would need to be supported by a tie line through it or the middle would drop out. Steel gobos are the cheapest option, with many designs working perfectly well as a stencil.
Glass slides are the next step. They allow intricate images to be produced with no tie lines. Even photographs can be produced using this method, or we can manufacture School Crests with a lot of intricate details that project well.
If you’re going to use glass gobos then you need to ensure that the lighting fixture you’re using is suitable. If the gate is too hot you will destroy the gobo.
Note that its not necessarily the wattage of the lamp that is the issue but how peaky the light is and the gate temperature.
An old fashioned 650W profile would often destroy glass gobos really fast, where the same manufacturer’s 1kW unit would have an even heat over the image area and there would be no issues.
It’s not unusual for us to be asked if a fixed light hanging in a community or a school hall will do the job of projecting a gobo.
The type of light required to be able to focus a gobo is called a profile. This is the light often used to focus on a lectern or solo spot, allowing you to achieve a sharply focused beam of light.
The common lights hanging in your rig that can’t be used to project gobos would be your Par lamps and your fresnels or other types of wash lamps that are designed to bathe your stage in light or wash your rear Cyc in colour.
Designs from various manufacturers vary greatly but you should soon pick out a suitable fixture if you have one in your rig.
A typical Fresnel (pictured left). Front lens has a rough texture to achieve a wash of light. You can make the beam wider and narrower with this unit but you can’t focus or insert a gobo.
A typical PAR lamp (pictured right). You can get different beam spreads, power ratings, long and short snouts and these days even get LED colour changing units, but you can’t insert a gobo anywhere and there are no lenses to focus an image.
Top image: Manchester Lane.