are made from a thin acrylic material and come in large sheets or rolls for placing over photographic lighting. To do this conversion, a template of the filter size needs to be created. This template can then be used to cut the correct filter size out of the ND lens gel (Fig. 3.3). After measuring the diameter of the inner portion of the lens, use a compass to draw a circle of the desired circumference on a piece of thin cardstock or paper. Once the template is created, check its fit on the camera lens and trim if necessary. The template should be cut so that it fits inside the area just smaller than the edge portion of the lens (Fig. 3.4).
Fig.3.3. Lens ND template.