ZOMEI 40.5mm Slim Gradual ND4 Filters for Sony A5000 NX1000 NEX-5T 5R 16-50 Lens Graduated ND filters can be used to darken a bright sky so that both the sky and subject can be properly exposed. They can come in a variety of shapes and sizes and densities and can be used in all types of photographic applications from still photography, motion photography and scientific applications. It is necessary or desirable to balance the light intensity in one part of a scene with another. This is especially true in situations where you don't have total light control, as in bright contrast landscapes. Sometimes it is also desirable to add color to part of the photograph. Fabricated from our high-quality color graduated filters which are color toned in one half of the filter and are smoothly graduated into the clear portion.