Fixed vs Variable ND Filters for Long Exposure Photography

This post is by Angela Andrieux from PictureCorrect

This article is based on concepts from The Advanced Photography Action Cards which are currently 71% off if you want to check them out.

A key piece of gear that is necessary for long exposure photography in bright daylight is the neutral density filter.

guide to long exposure photography

Types of ND Filters

There are fixed neutral density filters, meaning the amount of light blocked from passing through to the lens is a constant.

There are also variable neutral density filters, meaning the amount of light blocked from passing through to the lens can be adjusted, usually between 2-8 stops of light loss.

water long exposure

The temptation for purchasing a variable ND filter is convenience. You can get all of that range of exposure options using just one filter which is very nice.

However, there is a downside, and it’s important for you to realize that before you plunk down hundreds of dollars on a new variable ND filter.

  • A variable ND filter typically costs more than a single fixed ND filter.
  • Variable ND filters are round screw-on type filters. Therefore, you would need to purchase one that fits your largest diameter lens (more cost), and then purchase step-down rings so that it would fit onto smaller diameter lenses.
  • Step-down rings are notorious for seizing up and can be extremely difficult to separate.
  • Variable ND filters are thick and they will usually begin vignetting around the edges of the frame with any lens wider than a 28mm focal length.
  • Variable ND filters are known for leaving strange crosshatch looking artifacts in broad open planes of color—most noticeably the sky. This can be a real problem, as your long exposure photographs will often include the sky.

With a rectangular ND filter system, it makes it easy to stack filters (including graduated ND filters), as well as …