In the event that the primary suspension fails, secondary suspension must be fitted to mitigate the risk presented by a falling lantern . Uses at least one plano-convex lens , which when adjusted adjusts the focus of the lantern , thereby softening or hardening the beam edge. A second lens where fitted places the unit in the class of zoom profile. These lantern s can have the beam angle varied in addition to the slight change in angle caused by focusing the lantern. If a third lens is fitted it will be a condensor lens.
Profiles can project gobo s, or have the shape of their beam changed with the use of shutters.
They are used to produce dramatic highlights, or to provide controllable general illumination from longer throws than fresnel s. PVC tape aka insulating tape, LX tape or electricians tape.