Neutral grey filters can be used on various occasions. However, they are more popular with landscape photographers because they can produce exceptional landscape images. For the novice, choosing a neutral grey filter can be a fairly complex task because not all filters are created equal. What are the different neutral grey filters available? How can you use them?
The choice of a neutral grey filter is foremost based on its density. This is closely related to the amount of light the filter allows to pass through. The calculation of the percentage of filtered light is relatively simple. One divides 1 by the number of the filter. This means that the ND4 filter, for example, allows only 25% of the ambient light to pass through (¼), while the ND1000 filter (1/1000) allows only 0.1% of the ambient light to reach the sensor. Depending on the density, a distinction is made between :
- The ND2 filter, which allows only 50% of light to pass through.
- The ND4 filter, which allows only 25% light to pass through.
- The ND8 filter, which only lets in 12.5% light.
- The ND400 filter which allows only 0.4% light through.
- The ND1000 filter which passes only 0.1% light.
This knowledge is important for long exposure enthusiasts, as density has an effect on exposure time. With an ND2 filter, the exposure time will only need to be multiplied by 2, while with an ND400 filter, it will need to be increased by 400.
Importance of Diameter
Besides the density, the diameter must also be considered. The diameter of each filter depends on the size of the lens. Regardless of the brand, there are standard sizes common to all brands. However, sometimes you can find a filter perfect in terms of quality and price, but not the right size. There is no reason to give up the purchase. An adapter will easily solve the size problem.