The perils of using an ND filter.

Wreck, Cefn Sidan, Carmarthenshire (1/15th second at f16)

In October last year (see this post) I wrote about using a ten-stop neutral density filter at a rather surreal stretch of coastline near Aberdaron on the Llyn Peninsula. As waves came in I used exposures of several seconds to create blur and fizz from water moving amongst rather sculptural black boulders. I don’t claim for one moment that this was a new idea of mine, but I was happy to get good results from a technique that others had been using for quite some time. In fact, this kind of result has been possible since the very earliest days of photography. At first it was inevitable given the very limited sensitivity of the materials then available; there was no choice but to use long exposures. More recently apertures of f64 were possible with the large format film cameras used by certain landscape photograpers, with long exposures the inevitable result.  There are several examples in Paul Wakefield’s first book “Wales – the First Place” , published in 1982. Some photographers would use twilight only or even moonlight to obtain the same effect. But this technique really wasn’t mainstream.

Same subject, 10 stop ND filter, 2 secs, f11

Then I noticed a trend. Photographers were asking online about where to get hold of neutral density filters. For over a century and a half one of the main advances in camera technology was to make it possible to stop movement. And now people wanted to do just the opposite.  I just couldn’t understand it. I suppose I’m just a bit slow on the uptake, because images using ND filters were suddenly to be seen all over the internet.  Typically they would feature a coastal structure such as a pier surrounded by waves rendered silky and smooth by the use of a long exposure. And usually at sunset. A ten-stop filter was often used, which cut down the amount of light reaching the sensor to one thousandth of that actually available.  Lee Filters coined the term “Big Stopper” to describe theirs, while some cheapskates used glass from welding goggles as an economical substitute (….. ok, I tried that …..). Some photographs were actually very effective, but there were a much larger number of copycat images produced by the less imaginative.

Skokholm Island ; ND filter 5 secs @f11

I do now use a neutral density filter occasionally, but not necessarily when one might expect to.  An ND filter can bring an extra element of interest into a daylight seascape, for example in the image of Skokholm on the left, as well as at dusk. But there are times when I have reached for one, used it and then regretted it. Look at the main picture here. The sand snaking away from the camera in the wind is an integral part of the image, but too long an exposure removes it almost completely. Over a period of two seconds the sand particles are never in the same place for long enough to register on the sensor. Fortunately I saw the error of my ways before leaving the scene, removed the filter and had another go without it. In the previous post (click here) I described another example of NOT using an ND filter when others might have used one – in fact, were doing.

I always advise against using an ND filter to photograph waterfalls, too. I have to admit that I am a sucker for a silky waterfall shot, while others loathe them. In reality there is no correct way of making a still image of moving water, and it is down to personal preference in the end. But choose your day (cloudy, even light is ideal), use a narrow aperture (eg f16) , and a polariser, and you will easily be able to achieve an exposure of about 1/2 second – which in my opinion is just about ideal for a waterfall. An ND filter is almost never required.

So there we have it. Sometimes a little bit of subject movement will make or enhance an image , but an ND filter may remove it.  Use one at your peril!

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3 thoughts on “The perils of using an ND filter.

  1. Very nice post, Jeremy. I think I’ve only ever used a 2 or 3 stop ND filter, when experimenting with ICM, but I have promised myself to experiment more with other ways of exploiting the ND. Your advice is timely.

    On waterfalls, I was going to write no, half a second is too long, before realising that (a) this is all personal taste (how milky versus how crisp you want your water), and (b) to some extent it must depend on the speed (spate?) of the water. We’re just back from the Alps, and for one waterfall I exposed at a half, quarter and eighth of a second. For my money the eighth works best, and what’s more is just about manageable on a monopod (with a film 35mm camera, so ultimate sharpness not the issue).

    Anyway, thanks again

    1. Yes, you are absolutely right about the volume and speed of flowing water being another variable to take into account. A large volume of fast moving water will certainly require a shorter exposure (especially in sunlight). Experimentation is a very good idea (as you have found) and you will be able to choose your favourite. I was speaking in general terms from my own experience and my own preferences.

      I must say I have never used a 2 or 3 stop ND filter, but maybe I should try! I suspect mine is about 9 stops.

      Thanks for taking ther time to comment, Chris.

      1. I quite like the effect on receding waves with an exposure of around 1-2 seconds, and a 2 or 3 stop ND can often be useful for that. Not really so keen on the dead flat water effect of the 10-stop.

        The time I was thinking of above I was experimenting with both camera movement and also changing zoom during the exposure. You can get some really quite interesting effects (and also many, many uninteresting ones, which is hy it works much better with digital than film cameras).

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