Source Four Fresnel, ETC combines the efficiency of the HPL lamp with the singular optical qualities of the fresnel optical system to create the truly advanced ETC Source Four Fresnel. Traditional fresnel optics provide a unique quality of blending wash light and beam shaping via barn doors for well-defined, soft-edged area lighting. Source Four Fresnel combines this classic system with unique reflector design enabling the HPL 750W equipped Source Four Fresnel to equal the lumen output of other 1000W fresnel fixtures. Spot-to-flood focus is accomplished by large, easy-to-use knob for quick adjustments in inconvenient positions. The unique quick exchange socket design permits re-lamping from underneath the fixture without breaking focus in most situations.