Neutral Density Filters - What Are They? Do I Need One?
Neutral density filters attach to camera lenses and reduce the amount of light getting through to your camera sensor without affecting the colours (hopefully). Neutral density filters allow you to take long exposures in daylight, allowing you to flatten water and make clouds super cool, streaky, blurry, amongst other things. Neutral density filters allow you to use wide apertures in bright conditions and can also prevent you from getting overexposed photos in bright conditions.
And I have one that I absolutely love.
You can think of neutral density filters as sunglasses for your camera lens - yes, really.
And that was the answery bit. How utterly splendid.
Hi, and a very warm welcome to Episode 207 of the Photography Explained podcast. I'm your host, Rick, and in each episode, I will try to explain one photographic thing to you in plain English in less than 27 minutes (ish) without the irrelevant details. Yes, really.
I'm a professionally qualified photographer based in England with a lifetime of photographic experience, which I share with you in my splendid podcast.
Right - let's get straight into this.
Firstly, what are they? What are neutral density filters?
Neutral density filters are also called ND filters. And that is what I will call them for the rest of this episode. Saves me typing the words. Neutral means the colours do not change, and the density bit refers to how much light is blocked.
But the colours can change. With my ND Filter, I sometimes get a blue cast with long exposure captures that I have to correct. So, you will need to work out if your ND filter affects the colours or not. This is easy enough - take a photo without the ND filter and then take one with it and compare them. That is their one downside, but it is manageable if you know what you need to do and how to do it.
What are ND filters made of?
Glass or resin.
How much light is blocked by an ND Filter?
It depends.
An ND2 filter gives a 1-stop reduction in light.
An ND4 filter gives a two-stop reduction in light.
An ND8 gives a three-stop reduction.
An ND16 gives a four-stop reduction.
An ND32 gives a five-stop reduction.
An ND64 gives a six-stop reduction.
And an ND1000 gives a 10-stop reduction. And that is what I have. Yes really.
I don't love the ND2, etc term. An ND2 filter reduces the light getting through by half, the ND4 by a quarter, the ND8 by an eighth, etc. But this does not mean much to me.
I go with the stop reduction instead. Which, in my case, is 10 stops. Stops mean something to me. Quarters and eighths, etc, not so much.
A stop is a halving or doubling of light by the way. It all amounts to the same.
But whatever you use, the higher the number, the greater the reduction in light.
Filters and stops - the important bit.
This is important as we need to know what is going on with the exposure. A 1-stop adjustment can be made by
Using an ND2 filter.
Changing the aperture from f/8 to f/11, reducing the amount of light getting through by one stop.
Changing the shutter speed from 1/125th second to 1/60th second, reducing the amount of light getting through by one stop.
These adjustments all reduce the amount of light getting through to the camera sensor. And let us not forget ISO.
Changing the ISO from 200 to 100 gives the same overall effect as the changes above.
A practical explanation of using an ND Filter
This is the complicated bit. If you are in auto or semi-auto picture-taking mode, you don't have to make any adjustments, but you need to know what is going on.
Let’s take a typical exposure.
1/250th second, f/8, ISO100.
Add an ND filter giving a one-stop reduction in light, and to get the correct exposure, you need to either.
Reduce the shutter speed by one stop to let one stop more light in - so you change from 1/250th second to 1/125th second – more time, more light.
Change the aperture by one stop to a larger aperture, letting more light in - so you change the aperture from f/8 to f/5.6 - a larger opening means more light.
Or change the ISO to 200, which is one stop brighter.
But add a 10-stop ND filter and you will need to reduce the shutter to, wait for it - 4 seconds! Yes, really. 1/250th second to 4 seconds. And 1/125th second becomes 8 seconds. And 1/60th second becomes 16 seconds. 16 seconds. This is serious stuff!
Variable ND Filters
You can get variable ND Filters, with typical ranges being 2-5 stop reductions. I quite fancy one of these, but to be honest, I like my extreme 10-stop filter so much I have never got beyond that.
How do I attach an ND filter to my camera lens?
There are two different types of filters, ones that screw direct to the lens, and ones that have a holder that attaches to the lens that you put the filter into.
Filter holders are great; you can use one filter and holder with different-sized adaptor rings. My expensive ND filter comes with a holder, so I can use the same filter with my Canon 17-40mm lens, which has a 77mm filter thread size, and also on my Olympus 12-40mm lens, which has a 62mm filter thread.
This is a square filter with a square filter holder. And, not surprisingly, filters that screw directly onto lenses are round.
Yes, the big holder looks odd on the small camera and is a tad counterintuitive when thinking about reasons why you may have a smaller camera, but this is for occasional use. It’s fine, this does not bother me.
I have one filter, two adaptor rings, one 62mm and one 77mm, and one holder.
Step down rings – my top tip for you.
If you want an ND filter that screws into your filter thread, and you buy a filter for the largest lens that you have, you can then buy a step-down ring which means that you can use say a 77mm filter, with a step-down ring, on a lens with say a 62mm filter thread.
How utterly splendid.
Are ND filters expensive?
As with any question related to anything in photography, it depends. I have a Lee Big Stopper, giving me a whopping 10-stop reduction. And no, I am not being paid to say this – I bought this with my own money. Checking a well-known online retailer, this goes for around £100. Not cheap, I know. But I bought mine many, many years ago, and it is as good now as the day I bought it.
And the holder goes for around £30.
I say around because there are many different products and prices, but you get the idea.
And there are many pretty good, cheaper brands these days – check them out if you fancy buying one of these splendid accessories.
I always say buy the best gear you can afford, look after it, and it will serve you well for many years. I have had mine for well over a decade now.
But, if you are not sure, buy a cheap one and give that a go and see if this is for you. But there is a higher chance of getting a colour cast with cheaper filters. And a reduction in image quality, so choose carefully.
Graduated ND Filters
These are part clear, part ND, typically half and half with a transition from one to the other in the middle. You can use these to balance out an exposure when taking a photo with a dark foreground and a light sky, or a sunset over the sea. Or similar.
There are lots of different types, strengths, locations and hardness or softness of transition. And you need holders for these.
What can I do with an ND filter?
Take super long exposures in broad daylight. This is what I love to do. I use my ND filter to take long exposures of any kind of water. And let’s not forget clouds.
Long exposure photography in broad daylight
This is what I use my ND filter for. 1/250th second quickly becomes 4 seconds. And you can quickly get down to 8, 16, even 32 seconds. And this is a complete game changer.
Long exposures in broad daylight. And even longer exposures in low light, let’s not forget.
I have photographed many things with my ND filter, including
· A jetty on a Greek island with a super flat sea.
· A building with dreamy moving clouds.
· Various rivers with super flat water.
· Waterfalls with lovely blurry water.
· Moving vehicles.
· Moving trains.
· All sorts of stuff.
So, think of any photo with something moving in it, and how you can transform that photo by making the exposure loads longer. The possibilities are endless, so give it a go and let me know how you get on.
And if you have a 2-stop and a 3-stop ND Filter, you can stack them to get five stops, but the more things we put in front of our lenses, the higher the chances of a reduction in image quality.
Shallow depth of field
Sometimes you can’t get shallow depth of field because the light is too bright, and if you use a large aperture, your photos will be overexposed. An ND filter quickly fixes this. Same if it's so bright, your photos are overexposed.
Here’s something for you to do
Get a cheap ND filter that fits your favourite lens and get out there and have a go, and see what you think. To get the most out of one of these, you will need a tripod, though. But, if you don’t have a tripod, don’t let that stop you – you can use anything to rest a camera on.
Back in the day, I used to own a bean bag, and that worked just fine. There is always another way, so like I say, don’t let not having a tripod be a barrier. Get creative. And let me know what tripod substitute you come up with.
What if I use a phone to take photos?
Hmmmm. Well, I don’t know. So, I had a look. And guess what – you can get clip-on ND filters for phones. I don’t fancy doing this myself, but if you do, why not give one a go? I believe you will have to get an app, though, to have control over the shutter speed.
Not for me – too fiddly. I have cameras for all that faffing around, of course.
What do I do?
I use a 10-stop ND filter and absolutely love it. I have one filter holder and two adaptor rings for the lenses that I use with my ND filter.
I look after my ND filter with the same care I do all my gear, which is why this filter has lasted me so long.
But there is an issue with using a 10-stop filter. Put that on your lens, and you can’t see much. It is virtually impossible to compose a photo as it is so dark. And focusing becomes more of a challenge too.
Which is why when I am using my 10-stop ND Filter, I put my camera on a tripod. I compose and focus without the filter in the holder, then slide the filter in and then take the photo. I am using AV Mode, so I have set the aperture, and the camera chooses the shutter speed.
I also use back-button focus when I am taking photos using my ND Filter, and the built-in camera self-timer to make sure every long exposure photo I take is still nice and sharp.
So, all good.
But this is one time when I might well use manual mode and work out the settings myself, with the aid of an app, of course. No need to work this out the hard way these days!
Now how you do this with a screw in filter I have no idea.
And that is what I do.
Some thoughts from the last episode
21 composition tips to help take better photos of buildings. How utterly splendid. These were the things that came into my head as I wrote this episode. It was never planned to be 21; that is what I ended up with. And what an excellent episode it was, too. If I do say so myself.
Next episode
Same question, but this time about polarising filters. The other filter that I have. Yes, I have two filters and two filters only.
A quick plug for me and what I do.
Well, why not? If I can't plug myself on my podcast, where can I?
You have found this podcast, so why not check out the podcast website photographyexplainedpodcast.com? I have another photography website, rickmcevoyphotography.com, where I write blog posts about my photographs of buildings and other good stuff. On my courses page, you will find my course, How to Become A Real Estate Photographer. You can also find me on YouTube talking about my podcast and my blog - type my name in, and you will soon find me.
Get an email from me.
If you want a weekly email from me, fill in the box on any of my websites, and every Friday, you will read what I am thinking about photography-related.
That's enough of the self-promotion.
Ask me a question
If you have a question you would like me to answer or you just want to say hi, email me at sales@rickmcevoyphotography.co.uk, visit the podcast website, or text me from the podcast feed.
It is always lovely to hear from you, dear listeners.
This episode was brought to you by a cheese and pickle sandwich and a bag of salt and vinegar crisps. Yes, I consumed it before settling in my homemade, acoustically cushioned recording emporium.
I've been Rick McEvoy. Thanks again for listening to my small but perfectly formed podcast (it says here) and for giving me 27 minutes of your valuable time. I reckon this episode will be about 20-22 minutes long after I have edited out the mistakes and other bad stuff. Blimey – a short episode which makes a nice change.
Thanks for listening
Take care and stay safe.
Cheers from me, Rick
