The F10 Fresnel is specifically designed for the Aputure LS 600 series LED heads. The large 10″ (25cm) glass fresnel lenses gives a smooth edge transition and the beam is focusable from a narrow 15° to a medium flood of 45°. At 15º there is an exposure gain of 1.5-stops so great if you want to throw the light further or emulate sun through a window etc. The Fresnel’s design has ventilation vents to prevent overheating and the accessory barn doors give even greater control.