The NiSi 150 x 170mm Nano Medium-Edge Graduated IRND 0.9 Filter is a rectangular filter that helps to darken specific areas of an image such as bright skies, while allowing for a normal, unaffected exposure in the other regions of the image. The filter is densest at the edge and tapers to clear by the middle, with a medium-edged line of transition between the dense and clear areas. A neutral density filter with a medium-edged line of transition can filter the sky while minimizing its effect on the land. It is particularly useful for images that include elements like rooftops and mountains that protrude into the sky. Neutral density filters do not affect the coloration of the image and this filter provides up to a 3-stop reduction in light from entering the lens.
The design of this filter has 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 neutrality across the visible and infrared spectrums in order to eliminate color casts and ensure cleaner, truer blacks, 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.
This NiSi 150 x 170mm Nano Medium-Edge Graduated IRND 0.9 Filter is constructed from optical glass for clarity as well as color fidelity, and measures 2mm thick.