The NiSi Cinema 4x5.65" Nano IRND Soft-Edge Graduated 1.2 Filter (4 Stop) is a graduated neutral density filter that darkens bright areas of an image, such as skies while leaving the remainder of the frame unaffected.
The camera is different from the human eye. The dynamic range of the human eye is quite wide allowing us to see detail in bright and dim areas simultaneously. While modern cameras have made significant advances in range, they are still not able to match what we can see with our own eyes. They have trouble holding detail in scenes with a wide range of tones. To compensate for this, we can use ND Grads (short for Graduated Neutral Density Filter) to selectively darken an area of the frame, such as bright skies, while allowing for a normal, unaffected exposure in the other regions of the image. The NiSi Nano IRND Soft-Edge Graduated filters are characterized by a soft transition (they change from light to dark more gradually) and are used when the transition between light and dark areas is not so clear. A classic example is a shot in a mountainous area. The NiSi Cinema Range of IRND filters is constructed from optical glass for clarity with no loss in sharpness.