In this tutorial, I will give you a guide to ND filters in photography; what ND filters do, what ND filters to buy, what effects they create, and the like. I’ve also created a guide to ND filters that you can download and keep. This will help you calculate shutter speeds using our exposure calculator and advise you on what to buy.
If you are thinking of buying or using ND filters to create long exposure effects, then this tutorial is for you.
Why would you want to block the light coming into your lens?
Light is good, isn’t it? That makes the picture. It makes sense to think that if you block the light entering the lens, you’ll just create a dark, underexposed image.
When you block the light coming into the lens, you are forced to expose the camera to light for a longer period of time. You need to open the shutter longer to get the right amount of light into the camera.
Let’s see what effect an ND filter can have on an image. Below is a normal shot with no filter taken with a tripod at 1/30 second. You can see the ripples in the water and the clouds look clear, everything was frozen for that split second. Exposure details – 1/30 s, f22, ISO 400
And here’s a shot taken just after that with a 10-stop ND filter. The filter allowed me to increase the exposure time to 30 seconds. I still exposed the camera to the same amount of light, but this was exposed for a longer period of time.
When you do this, everything that is still will stay still ie trees and mountains and anything that moves will blur or blend. This shot was also edited in Lightroom to pump up the colors and contrast. If you wish, check out my other tutorial on how to edit images in Lightroom. 30 seconds, f22, ISO 400
Let’s look at them both together. The one on the left is a 1/30-second shot, and the one on the right is a 30-second shot with the 10ft ND filter on. Again, both were exposed to exactly the same amount of light, but with the ND filter on, you can let that light in slowly, which allows for a blurring of moving things like clouds, and also allows things to blend. such as ripples in water.
Also notice that only the shutter speed has changed. Aperture and ISO remain the same when taking these shots, and you must shoot in full manual mode. I cover this in much more detail in my next tutorial “How to use ND filters”.
All shapes and sizes
For those that screw onto the front of the lens, those that need to use the filter holder system and graduated ND filters it is best to use the filter holder system.
The screw types are very good value for money (around £10 or $15 each), you can get lots of different brands and they all do pretty much the same thing. If you are just starting out, I recommend getting one of these types that will fit your widest lens or your standard zoom lens, it will be great for long-exposure landscape shots.
Filter holder type
Cons – Much more expensive. This system is for the dedication to this type of photography or for those who have money to spare – the other is for practice or gaming.
Pros – Better quality. You can use them with other lenses, but you will need a reduction ring for the other lens. You can use ND filters in conjunction with other filters such as ND grad filters.
There are many brands and they are all very good. Here are some brand names – HiTech, Lee, Nisi, and Cokin, the latter being a cheaper brand.
ND Grad filters
ND Grads are mainly used to darken the sky and balance the exposure.
Below is an example of using a hard grad ND filter. The one on the left is a normal shot taken using the camera’s built-in exposure meter. The one on the right with a 2-stop hard grad ND filter. This darkened the sky by 2 stops to make the exposure much more balanced.
Different strengths of ND filters
ND filters are created in stops. Stop shooting is either halving or doubling the amount of light, eg making the image 1 stop darker or lighter. With ND filters, you always reduce or halve the amount of light. So a 1 stop ND filter stops the light by 50% or half. A 10-stop filter stops the light 10 halves in a row. You have to do it gradually, that’s important.
Remember, when taking long exposure shots, you only want to change the shutter speed. If you have a 2-second exposure with no filter, then you put a 1-stop ND filter, and you have effectively cut the amount of light coming into the camera in half.
Equipment you will need
A good sturdy tripod is a must. You will need some weight to keep the camera steady and still for long periods of time.
You will also need a cable trigger or a remote trigger. So you can use the camera in a setting called the bulb. I’ll teach you all about the bulb in the next tutorial when I’m out. You can get them quite cheaply on the internet, just type in ‘cable release for …..model of your camera.
I also recommend avoiding variable ND filters. Exposure times are harder to judge with these types, and you can sometimes see lines running through the image at its strongest setting. I would recommend getting a 10-foot and a 6-foot filter to get started.
There are many different brands and sets of ND filters. We want to recommend what we think is the best, whether you’re on a budget or not. We only have recommended companies that we or our colleagues use.