An ETC Source Four Enhanced Definition Lens Tube – 19º is a fixed‑beam lens barrel designed to produce a crisp, well‑defined light field with minimal edge distortion in ETC Source Four ellipsoidal fixtures. The 19º beam angle provides a medium‑tight spread that works well for isolating performers, highlighting scenery, or creating precise specials from moderate throw distances. Enhanced Definition lenses are engineered for sharper focus, improved contrast, and more even light distribution compared to standard lens tubes, which helps reduce color fringing and soft edges. This lens tube easily swaps into compatible Source Four housings, allowing designers and technicians to fine‑tune beam spread while maintaining the fixture’s familiar performance and reliability.