The distinct filter is designed to block the wavelengths of light created by mercury vapour, sodium and other Low CRI lights that are often used as streetlights. These lights are usually yellow/orange and are the primary cause of light pollution around cities. This makes capturing beautiful nightscapes near cities very difficult.
If you are an ight photographer then you almost certainly have run into the horrible yellow glow of light pollution or the ugly yellow cast that street lights spread over urban nightscapes. This light pollution and yellow cast can hide stars and mess with the white balance of your scene.
Without Natural Night Filter
With Natural Night Filter
Keep far away from light pollution
when enjoying the wonderful night
As you can see there is a significant difference in the yellow cast caused by the lights of the city. You also have an increase in the contrast of the image, especially in the areas that were washed out by strong nearby street lights. But you will also notice that you have a more magenta sky. Personally, I prefer the magenta sky over the yellow/green sky. But that is also an easy adjustment in post-processing.
The night filter is a glass filter that is coated with a double-sided multi-layer waterproof and oil resistant coating. This reduces ghosting and flaring and also prevents the natural oils on your skin from sticking to and smearing the filter.
The filters are available in a variety of sizes to fit multiple filter holders.