The ETC Source Four 19 Degree Lens Tube is a high-quality optical accessory designed to attach to any standard Source Four ellipsoidal spotlight body, providing a narrow 19-degree beam spread ideal for long-throw applications, key lighting, and precise pattern projection in theatrical and event settings. This lens tube transforms the fixture into a specialized instrument, capable of delivering a bright, crisp, and even field of light.

The lens system typically features advanced, dual aspheric lenses with anti-reflective coatings, which help in increasing light output and ensuring superior image quality. When used with a Source Four fixture, which utilizes a faceted dichroic reflector to remove about 90% of infrared (IR) heat from the beam, the lens tube helps keep the beam cool, extending the life of gels and gobos. The result is a clean white light and unparalleled imaging potential, making the 19-degree an industry staple for professional lighting designers. The tube simply slides into the fixture body and can be easily removed and replaced with other interchangeable lens tubes (e.g., 26°, 36°, 50°) to achieve different field angles. The lens barrel is focusable, allowing users to adjust the beam edge from a hard to a soft focus, with an integrated mechanism for smooth operation.