Custom Theatrical Lighting Filter on the Cheap

I was recently asked about creating or finding a custom lighting effect for my church’s Christmas Eve program. An outline of a cross was to be projected on stage; I searched a bit on the web but was unable to find instructions on making DIY filters. I had some ideas of my own and wanted to test them out.

The filter is a low budget GOBO filter made from kitchen grade aluminum foil and secured with kapton tape which is temperature rated for 500F/260C. This can be found on-line or at some electronics stores.

Step 1: Starting

I did not start completely from scratch; I had a theatrical light fixture as we have about a dozen theatrical lights suspended for the stage. I was able to repurpose one for this effect.

Step 2: Preparation

Removing the lens assembly, I was fortunate to find inner
frame areas to mount onto. I measured the opening and determined a size for the foil filter, 4” was chosen. The aluminum foil shape was cut with an X-Acto knife after placing it on a smooth scrap board. Other cutting techniques such as scarp-booking stamps should work as well.

Step 3: Mounting

Securing the filter within the fixture was quite simple. As stated earlier there was a internal ring frame that I was able to affix to. Using only four pieces of tape ¼” in length provided adequate security for the lightweight filter. Remember, the filter MUST be mounted upside down as the image is inverted by the lenses. Also the fixture used had slide dampers to shape the light, these were used to reduce the amount of light getting to filter and provide more of a heat block. I slide in dampers till they just reached the outline of the filter with the fixture illuminated.

Step 4: Results

The result was used to shine on an empty throne (chair) and though it was only panned in for a minute at a key moment during a particular song it had the desired effect.
No color filter was added though that would of course be simple.

Step 5: Other Complexities

The lighting bar in the church was mounted too close to stage to focus the light fixture by normal means of the lens screw in the provided slot. I had to extend the lens assembly further and secure with duct tape and a safety string to the set screw.