A variable ND filter is an essential bit of kit for outdoor portrait photography, especially if you don’t have much time and need to work quickly to get the shot, such as when capturing outdoor candid shots.
Variable ND filters get a lot of bad write ups and reviews and many buyers are disappointed with the image quality when a variable ND filter is used. I should point out that most of these bad reviews are from photographers who bought the variable ND filter for long exposure photography and not for outdoor portrait photography.
Variable ND filters are not suitable for long exposure photography and if you push an ND filter to its extremes, i.e. at its darkest, the image quality is terrible. I have tested a few variable ND filters for capturing long exposures in the past and the results were very disappointing. The bottom line is variable ND filters are no good for long exposures. If you want to take long exposure photos buy a strong single strength ND filter.
If you use a variable ND filter to slow the exposure by one to three stops there is a slight reduction in image quality, but no more than you would get with a single strength ND filter over the lens. Variable ND filters are more versatile than single strength ND filters, and this is what makes a variable ND filter more useful, more appealing and a better buy than single strength ND filters. There are many advantages using variable ND filters, and these are:-
If you have never used a variable ND filter for outdoor portrait photography I have to ask the question “why not?” If you have never used a variable ND filter for outdoor photography because you have heard and read “bad things” about variable ND filters and how the image quality isn’t very good I recommend you ignore these write ups. Trust me, the reduction in image quality using a variable ND filter up to three stops is no different than using a single strength ND filter. At four to five stops the image quality reduces but the images are still usable. Anything over five stops the image quality is significantly affected, however you will never have a need to use such a strong ND filter because the shutter speed would be so slow sharpness would be an issue.
It is easy to see that there are many advantages using a variable ND filter for outdoor portrait photography and I wouldn’t be without mine.
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Keen photographer addicted to cameras, lenses and everything photography related. Feel free to follow me in my photography ramblings, and if you have any thoughts, comments, queries or anything else to add I would love to hear from you.