Graduated gray filter
Grauverlaufsfilter or GND filter (from the English graduated neutral density filter ) are ND filters which are quite transparent to an end. They are often used in landscape photography to avoid overexposure to the sky when the soil is correctly exposed. The effect of a GND filter can only be simulated to a very limited extent by electronic image processing , since image information is usually lost in overexposed areas.
Gradient types
The filters offered are offered in different strengths and with different gradients (e.g. soft gradient = soft color transition; hard gradient = visible color border or hard color transition). As with the ND filter, the strength is indicated by the specification NDx.
GND filter with a soft gradient
GND filter with a hard gradient
neutrality
No filter currently on the market is color-neutral. The reason for this, in addition to the actual filter material, is the fact that where the filter darkens, light in the infrared wave range nevertheless penetrates the filter unhindered. The longer exposure time often results in a reddish color cast.