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This isn't really aimed at you, but I've never worked out why those things are called "lenses". They don't refract light in any significant way and are not shaped at all similarly to a lentil. Why aren't they "colour filters"? Is "lens" a techie theatrical-lighting term for them? (A near-erased memory from deep, deep offline storage tells me the theatrical term is "gobo"...)


A gobo is a small piece of metal sheet with a shaped hole cut into it. You insert them at or near the focal point of a profile spotlight and it projects the silhouette of the cutout.

Cheers, John