When to use a Neutral Density Filter

A common question I often get is “When would I use a Neutral Density filter?”  Below are some places and situation where I would use it.

  • Waterfalls – Wispy water
  • Landscapes – Wispy clouds
  • Portraits – To get a smaller depth of field/separate your subject from background
  • Anywhere where you want to get some motion blur

Wispy water at natural Bridge

A few weeks ago we were out shooting some waterfalls with my brothers and my dad, when one of the brothers pulls out a 10 stop Neutral density filter and screws it onto the front of his lens.  Wizardry…..Up til this point I had been struggling to get less light to enter my lens by shutting down my aperture and setting a low ISO which in turn would slow my shutter down to the point that I could get some wispy water falling down the falls. He in turn shot some amazing shots easily with this new fandangled filter. (he even let me use it for a bit! Sweet)

Multnomah Falls in Oregon

The drawback of reducing light the way I was attempting to do, was that my aperture was set to f22 ISO of 50 just to get a shutter speed of 1/10 of a second.  When you set your aperture down like this you can see any sensor spots and any water spots or dirt on the front element.  With the neutral density filter you can set your lens where it is sharpest say f8 or so. which would be a better place to have the f stop as the water spray hitting the front element if you are close to the falls will not be as noticeable.

There are many different neutral density filters on the market today from a Variable  ND filter all the way up to a 15 stop neutral density filter.  A 10 stop neutral density filter will block 1000 times the light coming into the lens so you could do some really long exposures with that one. (If without a filter you were 1/1000 of a second, with the 10 stop on it would be a full second for the same exposure) I think a neutral density filter of 6 would have been perfect for shooting the waterfalls that we were shooting the other day.

Normal exposure vs 10 stop ND filter

  • 1/1000 =  1
    1/500 = 2
    1/250 = 4
    1/125 = 8
    1/60 = 16
    1/30 = 32

A fun project might be to try to diy your own ND Filter. I have not done this but I have talked to some that have and they had some mixed results. I will try to build one and report back with my results.

Here are a few Neutral Density that one can pick up from Amazon.