Cbc America CBF-1 Cam Back Focusing Neutral Density Filter

adjustments when installing motorized zoom lenses. To assure that a zoom lens stays in focus throughout the zoom range, the camera must be backfocused when lens iris is wide open. The CBF-1 is placed in front Neutral Density Filter is used primarily to make the proper back focus installer. Protective case included. 3.0. The CBF-1 filter is an essential tool for the professional 4" x 4" square and made of glass - not plastic - and has an ND rating of of the lens to keep the auto-iris open during adjustment. The filter is