The 150x170mm Nano IR Medium Graduated Neutral Density filter from NiSi is specially designed for landscape photographers. This filter is made from high quality optical glass (not resin) with nano coating to prevent losing any single bit of detail.
The NiSi Medium GND 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 is particularly useful for images that feature buildings, mountains and other elements that protrude into the skyline.
By using neutral density filter the camera is vulnerable to infrared light which will cast the unwanted red color to the photos when shooting at small aperture. NiSi added the infrared protection coating layer to this filter which help to eliminate the infrared light through the lens to bring back the nature colour.