Photography - A guide to N.D. filters
Updated: Aug 19
I was asked the other day "what filter did you use for that picture", to which I replied a Lee 0.75 hard graduated filter. They looked blankly at me and somewhat confused, I asked them what was wrong, and their reply astounded me......."I've not seen that on Instagram, where do you get it from".
To say I was horrified was an understatement, so I decided to explain what a filter actually is to a photographer and not a person of the Instagram generation.
What is an ND Filter ?
A Neutral Density Graduated filter is a small piece of glass or resin (much better optically) that mounts on the front of your lens, half is crystal clear and half is darker depending on the grade you pic.
The idea is that it covers the sky portion of your picture which is usually a much brighter space than the ground. This enables you to get a more balanced and better overall exposure of the scene in front of you which as any landscape photographer will know, its an essential piece of kit.
Why Do you need ND Filters ?
Before I started using these I would have a scene that was either full of a beautiful coloured sky and everything else was so dark you couldn't make it out, or a nicely exposed foreground and a bright white over exposed sky, frustrating wasn't the word !
Then I discovered Neutral density filters and the difference was incredible ! Suddenly I was able to take balanced shots with everything exposed to match, well thats not quite how it happened as I started by falling for the biggest mistake of using a far too dark filter, but the concept was grasped and the use of filters was quickly taken up on every shot with very good results.
How do ND Filters work ?
The filter is mounted to the front of the lens with an adaptor ring that screws into the lens thread, and then a holder kit which clips to it. The filter its self slides into the holder and can be moved up and down according to the level of your horizon.
This will darken the sky according to the level of filter you have selected, they usually go up in .5 of a stop increments.
Hard OR Soft ND Graduated Filters ?
Now of course there are some scenes which have a nice flat horizon, for which a HARD ND Grad is the perfect choice, but what about those scenes where there are hills etc...and an uneven horizon, well for that you can use a SOFT ND grad filter which as the name suggests has a softer graduation so it blends a little easier, that said these will still leave a darker exposure on elements that they are covering.
The trick with filters and more importantly the shot, is to use them to your advantage, when the scene needs them, some scenes are better shot without and trying to expose for the elements that are most important for you in the finished product. Above all control the light for your situation and use it to your advantage, there are many pictures where a strong silhouette really adds to the feel of it all and the drama.
With this image above you will get the idea of how much darker each scene gets with the grad that you use, although it shows a full ND filter rather than a graduated filter.
So you will now be able to see the advantage these filters offer you in order to get the exposure you desire.
Now the hard part comes, parting with your cash for these cunning pieces of devilry, they vary in price from around £20 each for some basic ones right up to hundreds of pounds each, so is more expensive better ? Well, I would argue that if you have spent decent money on a great lens, why would you put an inferior filter in front of it ruining the crisp image you would get from your lens on its own. A very good brand of filters and one of the market leaders is Lee Filters, and that is my personal choice. These filters are all hand made and individually inspected before they leave the factory to make sure they are as perfect as can be and will enhance your picture not degrade it, they don't come cheap but quality never does and I would recommend them to anyone.
So which filter should you buy ? Now theres a question, I generally carry around 10 filters with me for most trips because you never know what light you will be up against. A 0.6 grad (2 stops of light) is a nice starting point for scenes that don't have the light source directly in shot, this tends to be a fairly good choice as an all rounder. The 0.9 grad (three stops of light) is better if you are facing direct and bright lighting although obviously won't completely quash direct sunlight.
This image will give you an idea of the effect of a filter and how it can help your scene improve, notice where the filter is placed darkening down the scene it is now much more colourful as it's correctly exposed.
A simple thing that makes the world of difference.
So why not just exposure blend I hear you ask ? Well you can do that, it's a personal choice and one that doesn't sit well with me.
Exposure blending seems to have really taken off in the past few years and the basic concept is to shoot two (or more) pictures of the same scene, one exposing for the sky, and one exposing for the ground, you then blend them together in photoshop so you get the best of both pictures. The trouble is by definition this just isn't a photograph to me, its two photographs ?
Now many pros do in fact do this and get good results, but for me I just feel it's not right to do and in a lot of cases it doesn't give a realistic picture as the light falling on details in the landscape soon gives it away. Some people however do actually do it and get very good results, but each to their own and I will be sticking with the ND Filter approach.
Why Use ND Graduated Filters ?
Once you have got to use Neutral Density GRADUATED filters and seen their merits it's a logical progression to try a full Neutral Density filter, this will slow down your exposure time and enable you to get some great dreamy effects with water and skies. These filters start around 0.6 (two stops of light) and go up to a huge Big Stopper (10 stops of light) and really can give a magic effect as seen below.
The above picture was taken with a three stop filter during quite overcast conditions but with some nice light still coming through.
The water has that silky effect because of the slow shutter speed (around 30 seconds) it wouldn't have been possible to shoot for so long if I wasn't using one.
Hopefully this will have explained a few points and helped people understand that when you say you used a "filter" it doesn't mean one of those awful image manipulating digital filters.
I hope you give filters a try and I hope you have found this helpful, as always happy shooting.
If there is a subject you would like to see covered in this blog then please ask in the comments section below and i'll do my best to cover it.