The 4 x 4" White Balance System is an over-the-lens filter to help obtain proper white balance settings in-camera regardless of the light conditions you are working in. By attaining proper white balance in-camera, you can avoid potential image degradation that can occur if heavily manipulating an image's color balance during post-production.
By placing this filter over your lens and pointing at the main light source, you can create custom white balance settings that are accurate to within ±50K of completely neutral. The diffuse quality of this filter is able to account for the actual color of the light versus the color of the subject matter itself, which is often a consequence of using a camera's auto white balance settings. Additionally, this filter can be used to identify a specific lens' vignetting and illumination properties and aid you in creating an LCC (Lens Cast Correction) profile for your specific lenses.
This translucent filter measures 4 x 4" and has a circular opening of 2.5" to accommodate the use of standard diameter lenses. Even though the circular opening of the filter is 63.5mm, it is compatible with lenses with filter diameters between 25-95mm. A soft, quality fabric bag is included to protect the ClearWhite filter.
Also included with the ClearWhite System is an 18% neutral grey card, which enables you to select a precise, constant tone from which to further obtain proper color or tone balance. This 4 x 6" polystyrene card has a white backing and a non-reflective grey surface for use in a variety of lighting conditions.