Neutral Density Filters
May 13th, 2009 by Keith Chaloner
I got involved in a conversation last evening about polarising filters and graduated neutral density filters and it occurred to me that the topic might be of interest to others.
I have both; a circular polarising filter that fits a couple of my lenses and not others and a set of Lee graduated neutral density filters.
The polarising filter was horribly expensive, I tried to use it once and couldn’t really see when it was doing something. I may have another go sometime; I really ought to.
The ND filters and holder came with a range of adaptors to allow its use with a number of lens diameters. Although the holder came with an elaborate lens hood it didn’t seem possible to use the hood with the filters; not sure why I was sold something that didn’t serve a useful purpose, or why I didn’t make sure it was worth buying in the first place. It is a very nice lens hood but I already have them with the lenses I bought.
I think I used the ND filters once when I bought them but it seemed such a hassle getting them out and attaching all the bits and bobs that I decided life was too short and they could keep my polarising filter company; and I would try not to think too often of what they cost me.
Then maybe six or ten months ago I got fed up with over bright skies and decided to have another go. And what useful things they are! I use them most of the time I can bother to assemble the bits, which is quite often. I know the theory is that you should take a reading from the grass (say), then a reading from the sky, work out how many stops you need to correct for and then select the correct value ND filter, and away you go. Only I don’t do that! I start by sticking the .9 ND filter in (I believe it corrects for 3 stops but I don’t know how .9 = 3). After I have tried the shot, if the sky is still too bright, I stick another ND filter on (the holder takes 2 at a time and I think can be adapted for more). I generally put the .6 in (2 stops) to give me 5 stops in total. This generally does the trick although I maybe reduce the exposure a bit as well.
All in all I have found it definitely worthy doing and I recommend those of you who haven’t tried it have a go. I checked on the web this morning and it looks as though a Cokin set is available for just under £50 which seems reasonable. I used Cokin filters 30 or so years ago but have no current knowledge of them. Perhaps other members of the club can comment on their efficacy to help those who may contemplate purchase.
Anyway the point of my rambles is that ND filters are well worth acquiring and using, particularly for landscapes.
I have circular polarisers for use with my lenses and they can be helpful but, if it’s skies that they are being used for, then the effect is most noticable when shooting at 90 degrees to the sun. By definition therefore, they give a variable and unsatisfactory effect if one is using a wide angle lens. But wide angle lenses tend to require large filters and the larger the filter the greater the price - and the less effective they become for this purpose!
Nevertheless they are also very good for reducing specular reflections from water and hard surfaces and they also have the effect of a low-powered ND filter.
I also use Cokin variable density filters and they seem to work well.
I recently purchased a set of the Cokin filters and used them for a recent trip to Exmoor. I was really pleased with the results, I to was fed up with washed out skies.
I used ‘Live View’ on my camera to see the image I was taking and had the histogram showing as well so I could adjust exposure while keeping an eye on the histogram, which as a novice I found useful. And the results, yes I was pleased with them as well.