Kase Wolverine KW100 100x150 Double Grad Soft GND0.9 + Hard GND0.9

Kase Wolverine KW100 100x150 Double Grad; Soft GND0.9 + Hard GND0.9
This filter is specially created to compensate for the uneven exposure caused by the light difference between the top and bottom parts of the photo during the shooting process.
The soft GND0.9 and hard GND 0.9 are used to balance the air and ground.
 

GND (Graduated Neutral Density) gray gradient filter
GND gray gradient filters have a gradation (gradient) that varies in strength and density across the surface of the glass filter. The filters are often half ND gray filter and the other half is clear. When photographing with long shutter speeds, it is important to be able to control the light. Depending on what you want to block the light from, you can place the gray gradient filter in the correct position. A GND gray gradient filter is often used together with an ND gray filter.
The gray gradient filters have different types of transitions, with different application options.
A soft edge S-GND gray gradient filter is best suited for mountainous, forested or urban environments, where the horizon does not have a flat straight transition.
A medium edge M-GND gray gradient filter can also be used in similar areas to the S-GND, but care must be taken as you need to watch out for dark lines that may appear over trees or buildings.
A hard edge H-GND gray gradient filter is best used in open areas where there is nothing on the horizon, such as coastlines and open plains. With a hard gray gradient filter, the transition from light to dark is clear and fast and is ideal for sea and desert landscapes.