The Neutral Density Effect (May the froth be with you.)

Guest Post by Gary Lapslie

As a photographer myself, I often set aside time to check out work by other photographers on the internet ………….

No, not those sort of photos!

I have noticed something of a trend at the moment, where images of moving water appear to have a smokey almost ethereal quality to them. I am always curious to learn a new technique so I thought I would give it a go and report back to you guys with what I found.

Neutral Density or ND, what is it and how is it done?

Well, put quite simply it is a filter effect added to your camera lens which while not effecting the colour reaching the sensor of your DSLR. It does cut down the amount of light. This allows a longer shutter speed than normally possible in daylight.

All sounds like complicated hey, not at all….  Keep reading.

If by adding this magic filter we can have a longer shutter speed than would be possible without ending up with an image which is over exposed (too white). This means that what we end up with is a result where anything that moves while the shutter is still open appears to have a slight blur and objects that remain still are sharp…. Coolio.

That’s my simple version however if you want more technical stuff check out the web …. it is full of info on the subject..


Now you all understand the basic principle, you will want to choose a filter to buy, and now the fun begins.

You will need to decide which lens you want to use from your collection, my advise would be to choose the lens you would normally take on a walk with you, in my case i picked a trusted Nikon 17 to 55mm which covers most general eventualities, plus it is not in any way specialized so you will probably all have something similar (even you Canon types).

Somewhere on you lens will be marked the filter size which is the size of the thread at the front of the lens, in my case 67mm.

Now time to raid the piggy bank, the selection out there of ND filters is vast and all claim to have great optical qualities. Some come in kit form with a number of filters from 2 to 10 which is basically an indication of the darkness of the filter glass. Others offer a variable alternative with a rotating ring to set the graduation of the filter all in one piece similar to a circular polarizing filter .

The most alarming thing is the range in price, anything from a few pounds all the way up to silly money for the average enthusiast.

As I intended to go looking for a stretch of fast moving water to try this out I opted for the all in one variable version as I had visions of juggling multiple filters near fast water and dropping at least a couple of them in the drink, followed by me trying to catch them (not cool). As for the cost, given I intended to write this post and for you all to have a crack after i opted for a budget version around 20 squids which I could justify for something I would only use now and again.

Armed with your new addition to the family screwed firmly to the front of your camera and some sort of support device for your camera (tripod, wheat bag, gorilla pod to name but a few) as we will be using around a 1 second shutter speed making hand held a non option.

So with everything prep’d and ready, its off to take some pictures we go.

First frame your shot and take a couple of images on auto with the filter set to minimum effect just to make sure you are happy with the focus and the shot framing in general. Its worth a mention that with the filter set on full effect (i.e. max) your auto focus will most likely not work, as hardly any light will be getting to your sensor. This is possibly another good reason for using the variable version as I found i did have to keep turning the filter back to minimum to check my focus.

You will need to set your dials on the camera to full manual as shutter priority (Most commonly TV) will try to compensate for the lack of light and give you the minimum depth of field possible in a vane attempt to make up for the filter effect.

In my case I had a fairly bright day to play with so for my first go I opted for a 1 second shutter speed, a mid range F-stop, maximum filter effect, ISO set to around 200 and no zoom on the lens.

This I found to be a fair starting point from which I could either loose some filter effect if the shot was too dark or raise the F-stop if things where a little too light without having to deviate from my 1 second shutter speed.

To be fair I doubt I would like to try this technique on a film camera as there is an amount of wasted images before you get the result you are happy with, in other words you will kiss a few frogs before you find a prince or princess depending on your preference.

One useful tip which I found which may seem obvious to you all. However I only found this through failure, is that should you choose a scene similar to those I tried i.e. trees and water then it is quite important to ensure you do this on a day when the wind is not moving the trees too much otherwise they will cease to be the stationary element of your image and will take on the same blur effect as the water which in effect makes the whole image just look a little out of focus.

In conclusion I would recommend that you all have a go at this as the results can be quite rewarding for a fairly low cost and I feel sure you will find many other applications for the technique, the only restriction being your own imagination.

For those on a budget

During the course of this trial I also found that for those who simply can not justify the cost of a filter there is an alternative which although it does not produce the full effect it will give you something quite close as follows.

With no filter attached, set your camera to shutter priority which will allow you to set you own speed manually and the depth of field (F-stop) will become automatic.

Point you camera at the subject, focus as normal and gradually reduce the shutter speed. As you do this you will notice that the automated F-stop (or aperture) setting will go up in order to compensate for the length of time the shutter will be open.

At some point you will reach the maximum depth of field possible after which it will not get any higher.

Now you are at the optimum achievable without a filter before exposure issues start to occur. In my case I could get to around 1/5th of a second on a clear day which for faster subjects like flowing water produces a similar effect as can be see in the images below. The first of which is fully automatic and the second employing the shutter priority technique described above.

No doubt there will be those out there who use various photoshop type packages and will no doubt tell you this effect can be added during processing however for me there is no feeling quite as rewarding as using the camera to produce these type of effects without cheating.

I do hope you all have hours of fun with this, just as I did. Happy snapping.


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By | 2016-11-25T09:42:46+00:00 May 18th, 2012|Photography|0 Comments

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