Common questions about ND filters

Yes, these types of filters have many names. But whether you talk about grey filters, ND filters or neutral density filters, they all mean the same thing.

"Neutral" means that the filter has no influence on the color reproduction or intensity. "Grey Filter" means that the filters are greyed in different gradations / intensities.

A screw filter is screwed onto the lens of the camera, while a plug-in filter is inserted in front of the lens using a holder. Screw-in filters must always have the respective size of the filter thread of the lens (e.g. 72mm), while the holder of the plug-in filter can be plugged directly onto the lens and is relatively flexible in size.

Depends on what type of filter you prefer. If you use screw filters for your lenses, you will also need individual filters due to the different size of the filter threads or you can use so-called Step-Up rings.

So that you don't have to buy a new filter for every lens with a different diameter, there are Step Up and Step Down rings. These are adapter rings for lenses that make it possible to use filters on lenses with larger or smaller diameters.

Of course, screw filters of the same diameter can be screwed together and plug-in filter holders usually have several slots to be able to insert different filters in a row.

Yes. ND filters are normally used to reach longer exposure times. As a rule of thumb, handheld works down to roughly 1/focal length – about 1/50 s on a 50 mm lens. Long exposures with an ND filter usually sit between 1 and 30 seconds, and for those you need a tripod or the shot will be blurred. A tripod lasts for years, so it is not the place to save money.

Of course, that's possible - you simply take pictures at the late blue hour or at night. During the day it is too bright to get longer exposure times without filters. This is where the advantage of ND filters comes from: you can not just take long exposures at these times of the day, but also during the day.

Vario or variable ND filters are usually screw-in filters that combine several filter strengths in one. Turning the outer ring changes the strength and with it the exposure time. Watch the build quality: cheap variable filters tend to show a dark cross in the frame at their strongest setting.

A camera with a manually adjustable exposure time, because you want to reach 20 seconds and beyond. A lens that takes a screw-in filter or a holder. A stable tripod, because nobody can hold a camera still for that long. A spirit level, which most cameras already have built in. And a remote or cable release. On top of that, ND filters in a few strengths, for example ND8, ND64 and ND1000.

The images have to be taken in RAW, as that keeps the most image information. Open the file in a RAW editor and use the eyedropper to set the white balance. Pick a colour-neutral object, a grey stone for instance. The editor applies that white balance to the whole image and the colour cast should be gone.