NiSi Explorer Reverse-Graduated IRND Filter (100 x 150mm, 3-Stop)

This filter achieves its effect with a 0.9 band of density across its center region that provides a 3-stop reduction in light from entering a lens. This band extends approximately 4mm in both vertical directions and tapers to a 0.15 density that provides a 0.5-stop reduction in light at the edge above it. Directly below the 0.9 band of density, it tapers to clear, with a hard-edged line of transition before the clear area.

The placement of a 0.9 band of density with a clear area directly below allows the filter to match the positioning of the sun when it is at, or immediately above, the horizon. In such instances, the sun can appear closer to the center of an image as opposed to the upper edge, and an increase in brightness is created that is more prominent on both sides of the sun than above it. This pattern of brightness corresponds to the density pattern on the filter. The hard-edged line of transition in this reverse-graduated neutral density filter is useful for hard transitions between the sky and land, while the 3-stop to 0.5-stop gradation is applicable to multiple regions of brightness within the sky.

NiSi Explorer filters are constructed from tempered Schott B270 glass for shock resistance as well as increased optical clarity and color fidelity. The design of this filter has also been optimized for use with digital sensors and to promote nearly flat attenuation of visible and infrared light. Due to imaging sensors' greater susceptibility to infrared light, compared to traditional film, color casts can occur when photographing darker subjects that require increased exposure times. To provide a high level of neutrality across the visible and infrared spectrums and to eliminate color casts and ensure cleaner, truer blacks when using the filter, one layer of NiSi Optical Nano Coating is applied to each of this filter's surfaces. The nano coating associated with this filter also results in an improved beading effect when in contact with water or oil for greater cleaning efficiency.