Using a neutral density filter

ND filters can be used to produce some great images

Lee Filters – Big stopper neutral density filter reduces the light by ten stops. You can produce great images like this one from the video.

Sometimes you need a long exposure…

However, to take a very long exposure in daylight will mean too much light will burn out your picture. So you need to turn down the incoming light. For that you use an ND Filter. Here is how they are used.

Remind me, why do I need this?

Remember, shutter speed controls movement blur. If you want to show a car looking blurred as it goes past you might set the shutter speed to about a fifteenth or thirtieth of a second. But what if you want to capture a much less obvious movement or a really slow movement? Say two minutes? Well, normally the amount of light coming in will burn out the shot. Of course you can use a really small aperture (eg: f22) and let less light into the camera. But on a bright day two minutes will still burn out the shot. This is where Neutral Density (ND) filters come in. They are specially darkened filters that cut the light down allowing you to extend your exposure. With one of these you can do some awesome effects.

10 stop Neutral Density Filter (video)

In the video we see the making of a picture (above) by using the Lee Big Stopper Neutral Density Filter. This ND filter is very dark, which takes down the light by 10 stops. It creates a great effect on of the water swirling under the pier. This is the darkest type of ND filter.

ND filter strengths

ND filters can reduce the light entering your camera for up to 10 stops. This allowed 2 minute exposures in the video. However, there is also ND2, then ND4 and ND8. Other strengths exist, but these are the most common. They allow you to have shorter exposures so you can adjust the exposure to the needs of your shot. You can also put them together so an ND8 + ND2 gives you an effective ND10 – the strength in the video.

ND Grad.

Another of these type of filter is the graduated Neutral Density, or ND grad. The use of an ND grad is quite specific. It is used to reduce the incoming light from the sky when you have a bright sky and dark ground. If you expose for the ground the sky burns out. If you expose for the sky the ground is too dark. The ND Grad. helps prevent the sky burning out.

The ND Grad. is dark at one end and clear at the other. The two zones meet in the middle where the clear graduates into grey. Put the filter over the lens so the line of clear/grey graduation lies on the horizon, darkening the sky. Now, you can expose for the scene and get even light distribution. The next video will show you how this type of ND is used.

Mike Browne  External link - opens new tab/page
Problems?

No, filters are simple and easy to use. There are some important things to remember…

Always use a tripod. It is impossible to hold a camera steady for more than about half a second. After that your image will start to get blurry.

You need to be quite precise about lining up ND Grads with the horizon. Take a little practice before going out to do the BIG shot.

The darker the ND Filter the more there is a tendency to impact on the white balance. Sometimes you get a blue colour cast, sometimes a red one. You can remove this in post production if you are using the RAW file format. Alternatively you can test the filter with your camera and adjust the white balance setting in-camera to correct for the aberration. Most of the stronger ND filters have this colour-shift tendency. it is exaggerated by the sensor type. CMOS sensors tend to magnify the effect.

Sometimes getting the exposure right is a matter of experimentation. Take a few test shots and make sure you do some “Chimping”.

If you are buying ND filters, especially ND Grads buy square ones. You can buy adaptors for these to fit any lens and it allows you get creative in more ways than round, screw-on filters that only fit one lens.

There are many different kinds of filters which produce a huge range of fun effects in-camera. Many of these effects cannot be processed into the shot later. The square filter system shown in these videos allows you to expand your collection and develop a new set of skills without buying an expensive filter for each lens.

ND Filter set…

3 full ND filters
3 graduated ND filters
Full fitting kit for a range of camera
and lens sizes.
10 Adapter Set + 6 Filter ND2 ND4 ND8 G.ND2 4 8 For Cokin P Canon Nikon Sony LF6

Please leave any questions or comments you have about these in the comments below.

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By Damon Guy (author and Photokonnexion editor)

Damon Guy - Netkonnexion

Damon Guy (Netkonnexion)

Damon is a writer-photog and editor of this site. He has run some major websites, a computing department and a digital image library. He started out as a trained teacher and now runs training for digital photographers.
See also: Editors ‘Bio’.

3 responses to “Using a neutral density filter

  1. Thats cool! Was there a colour cast at all?

    Like it. I will give it a try as soon as mine arrives. Not here yet!
    Damon

  2. Damon (Editor)

    Yes, it is true that more expensive filters are not as bad when it comes to a colour cast. However, it depends where you are taking the shot, the weather conditions in general and the colour warmth of the surroundings. So it is not always the same colour cast.

    Removing the colour cast is not the easiest thing, but by increasing the colour temperature of the shot, and using the colour balance and curves functions it is usually possible to provide a perfectly good colour balance if you are working with a decent RAW developer application.

    You an often reduce the blue colour cast in-camera by setting the blue colour up as a custom setting to reduce the effect. This is probably not as effective as working in a good image editor. However it may be worth experimenting.

    I am dubious about the welding glass. I have actually tried it and got poor results. It had an inconsistent colour distribution leading to a mottled effect and there was a slightly green colour cast which is more difficult to remove than blue.

    Anything that interferes in the photographic process has a penalty attached. I agree that this is less than perfect. On the other hand it is like all other pieces of equipment. You have to balance the benefits against the downside. Then, when you know your tools well you can make a judgement call about how effectively you can use a particular tool in a given situation. That is part of the skill you develop as your photographic knowledge grows. ND filters are a solution to a problem – they are not the perfect choice. No solution is perfect. You have to work with the merits.

    I would be most interested to see how you get on. I would be please for you to report back here when you have tried them out.

    Thanks for commenting.
    Good luck and best wishes,
    Damon

  3. Damon (Editor)

    It is true that the more expensive filters take off the colour cast, but even they have a little. You can compensate in camera by setting the colour profile as a custom setting so it removes the blue at source. However the use of a RAW developing function in an image editor is probably the best way to do it. You can use the sliders and curves functions to help you with that.

    I am unconvinced about the welding glass. It is likely to be un-calibrated so you will have to experiment with it. I tried one once that did not have an even distribution of colour so the effect was mottled. Rubbish. It also had a green colour cast that was more difficult to get rid off than blue. At least with blue a warmer colour temperature evens out the blues.

    As with anything that interferes with the photographic process, there is a penalty. You have to off-set the benifits aginst the losses. Then, when you know your tools use them where they give the greatest effect. Using filters, like any other equipment is a skill that takes time and practice to develop.

    I would be most interested to hear how you get on. Please keep us informed. Thanks for commenting.
    Damon