How to choose an ND filter for long exposure photography?

This article is the second in the series of articles on ND filters. The first article explained what an ND filter (or neutral density filter is), what it’s used for and why photographers use this essential accessory to take beautiful long exposure photos. If the first article convinced you of the usefulness of this type of filter, then you are probably now be asking yourself which ND filter you should choose. You will have to choose in relation to density, brand, quality and time of shooting.

If you want to learn all about photography and how to best equip yourself with an ND filter, then this is the article for you.

By the way, I personally use a lot of lens filters (Polarizing, ND, grad/GND) instead of spending time on Photoshop and Lightroom. It’s my choice. I’ve already explained in my previous article that ND filters can also be used with a polarizing lens filter (a “pola” as it is also called). Even if it requires bringing a little more equipment in your photography bag, the result seen in your photos when using the two filters together will definitely be worth it. A little reminder; a polarizer saturates the color rendering and increases the contrast of your image.

As Amazon Associates, we earn from qualifying purchases. It means that, all the links linking to camera gear in this post are redirecting to Amazon stores

In this article, I will explain the characteristics and things you will need to take into account to help you choose your neutral density filters. I am focusing here on taking long exposure shots, one of the most important techniques to master for some great travel pictures. In my opinion, using an ND filter is one of the best landscape photography tips I can give (with the use of a circular polarizer…).

Here are the practical techniques required for using each of the different ND filters, as well as the advantages and disadvantages.

The screw-on circular ND filters are placed directly in front of your camera lens. Each filter has a specific diameter (e.g. 55mm, 82mm, etc.). The operation is therefore rather straightforward.

Here is an example of a circular ND filter, the very good B+W 106 (ND64). I used it for a very long time on my wide-angle lens – More details on Amazon

The second type of ND filter is square (or rectangular) and used with a filter holder. Basically, you will need to buy an adapter ring which is placed in front of your camera lens on to which you will then attach a filter holder. The filter holder contains several slots so you can slide different filters into the holder at the same time.

Advantages :

• This system does not require the purchase of several ND filters since your filters are inserted into the filter holder which fits on your lens via an adapter ring,
• Only adapter rings will have to be purchased to fit the diameters of your different lenses (which is cheaper than buying ND filters for each diameter).
• This system is perfectly suited for the use of neutral graduated filters (GND), which are very useful in landscape photography.

I use Lee’s adapter ring to attach the filter holder system to my camera lens on my Canon EOS 6D – More details on Amazon

Disadvantages :

• It is not possible to use a UV filter with this system,
• The kit (filter holder + adapter ring) is usually more expensive than a screw-on circular ND filter,
• The set-up requires a little more time and practice to perfect,
• The whole thing takes up more space in your camera bag.

So there you have the information you need to help you choose your ND filters according to the different types available.

Yes, choosing an ND filter is now going to get even more complicated! You also have two options for your ND filter depending on the density you desire, which can be fixed or variable (with a gradient).

The fixed density ND filter only has one level of density (obviously) which you will need to choose according to the type of photos you want to take and the time of day in which you want to take them (this is discussed further in the next paragraph). I only use fixed ND filters, which I am quite satisfied with.

Here is an example of a Hoya variable density filter – More details on Amazon

The variable Neutral Density filter allows you to adjust the density of the filter according to the scene you want to photograph. On paper, this seems like the ideal solution however, in reality, variable density filters are made up of two equally sized, stacked polarizing filters therefore the thickness of the glass is greater allowing for a higher probability of optical defects in your photos i.e. light and vignetting.

Opinions seem to be divided on this issue and I have not had the opportunity to test these variable filters personally. If in doubt, for the time being, I recommend using fixed density ND filters, which are, in fact, the most commonly used. I can’t advise you on the best variable ND filter yet, but I am curious to test one!

After choosing the type of ND filter you want and whether you prefer fixed or variable density, the next important factor to consider is the actual density of your filter. That is to say, we need to choose the opacity of the filter, the “darkness” of the filter. So how do you choose the density of your ND filter? In my opinion there are two factors to be considered in tandem before you make your purchase.

That is the first thing to consider. The majority of people who buy ND filters use them for long exposures, especially of the sea, waterfalls, streams, etc.

You need to ask yourself if you want to take “standard” long exposures, i. e. to simply capture the movement of flowing water or if you want to create a mist or fog effect or smooth the sea completely. Now what am I talking about?

It’s the difference between the two photos below:

Once you know what type of photo you want to take, you will need to think about when you are going to use the filter the most. During the day in broad daylight? Early or late evening? At Night?

To summarize and simplify it for you, if you plan on usin an ND filter mostly for taking photos in full brightness you will need to buy a filter with a high density. In fact, light is a much bigger problem at midday than it is at 8 am or 5pm. To counter this strong light (and to achieve a long exposure), you will have no other choice than to buy an almost completely opaque (black) ND filter in order to extend your exposure time. In the early morning and evening, the light is weaker so you will be able to use a less opaque ND filter to achieve the same long exposure as at midday.

The different densities of the ND filters

It is not easy to understand how the different densities work when first starting out, and the manufacturers certainly don’t make it any easier. However, it is an essential factor when choosing your ND filters.

Depending on the brand, the density will be displayed as:

• The optical density of the filter: ex: 0.3 or 1.2
• The filter coefficient (number behind the “ND”): ex ND 4 or ND 64

Here, you’ll found two tables in order to summarize the factors, which need to be studied in correlation.

The table below shows the correlation between the optical density of the filter (D), the coefficient (ND) and the speed to be adjusted (IL “stops”).

E.g.: with an ND 64 filter, you lose 6 stops (IL). To compensate for the loss of light from the filter, you will therefore have to reduce your speed by 6 notches. Is that enough for your use?

The second table shows you four filter types of different densities (ND 8, ND 16, ND 64 and ND 1000), the loss of stops (IL) and the correspondence in terms of shutter speed. This table should be quite useful in helping you to choose your ND filters!

Ex: 1/250 without filter = 1/15 with ND 16 filter (loss of 6 stops)

To give you an example: in the middle of the day, your camera might give you a shutter speed of 1/500 without filter (and with the lowest ISO). If you buy an ND 16 filter, you will only get a speed of 1/30, which will not be enough for a really long exposure. On the other hand, with the same shutter speed (1/500) but using the ND 1000 filter, you’ll obtain a 2 second exposure.

If you have now understood how this works, you should be able to choose the correct ND filter, right?!

There isn’t actually a ‘best’ ND filter. My advice is to choose your ND filter according to the time of day of your photoshoot and your desired rendering. When I was starting out, I bought myself an ND 64, then later I purchased an ND1000

• I use very few ND filters below an ND 8 (even ND 16). The loss of brightness and necessary shutter speed adjustment is, in my opinion, too low for these filters to be useful in most situations. In the middle of the day, for example, you will not be able to take those desired long exposures (e. g. with an ND 16, 1/250 without filter = 1/15 with filter).

• However, the ND 16 is suitable for long exposures in low-light conditions (undergrowth, shadows, early and late evening). Ex: ND 16, 1/30 without filter = ½ second with filter),

• I do prefer the ND 64 (loss of 6 stops), which I think, is perfect for long exposures during Golden Hour (early morning and late evening). Without a filter you will have shutter speeds from 1/60 to 1/15, while with an ND you will get slow shutter speeds from 1s to 8s, which is perfect for a “standard long exposure”, it also stops you from having a completely blurred effect. This is probably the first ND filter I would recommend that you purchase. However, for photos taken in direct sunlight, the opacity may not be sufficient, depending on the light intensity of the scene.

• The ND 1000 will be perfectly suited for long exposure in the middle of the day/sunny day (1/250 without filter = 4s with an ND 1000). However, it does have its limits in low-light conditions because long exposures may immediately become too long (e. g. 1/15 without filter = 1 minute with an ND 1000). For seascape, for example, the effects will give you completely smooth, flat and white water! By the way, if you’re shooting near the sea, I do recommend using a cleaning cloth for your filters.

What is the best ND filter? which one to choose? My recommendations!

Which ND filters are best for long exposures in the daytime and/or for very long exposures (ND 1000)

• Screw-on ND filters :
  • Haida ND filter
  • B+W ND filter

• Filters for filter holder system:
  • Nisi ND filter
  • Big Stopper ND filter (from Lee)
  • Hitech ND filter

For those who are interested in very long exposure, in the middle of the day, there are a few high-density filters known to be of very good quality. Here are 3 in particular:

• Lee Super Stopper ND filter (15 stops – Density 4.5)
• ND Nisi  filter : 15 stops
• ND Nisi filter: 20 stops

If you wish to use a graduated ND filter you will need a filter holder. I will discuss these filters, which partially reduce the brightness of a scene (mainly the sky, which is often overexposed compared to the darker foreground) in more detail in other articles.

If you want to go further, I suggest you to check out our full article on Kolari ND filters, great ND filters that we had the opportunity to thoroughly test!

Not all ND filters are of equal quality; although there are usually good price/quality ratio ND filters on the market I haven’t personally tested any. However, I would advise you to avoid the cheaper ND filters, which are known for their poor quality. Here are the best brands known for their overall quality and the ND filters they offer:

• B+W ND filters
• Lee ND filters
• Nisi ND filters
• Hitech ND filters
• Tiffen HD filters
• Heliopan ND filters
• Hoya ND filters
• Rodenstock ND filters
• Marumi ND filters

Of course, other brands exists like Cokin or Singh Ray.

Well there you are. I hope you liked this article and that you now have all the information you need for choosing the correct ND filter to suit you and your camera for those long exposures you desire. Now it’s time to figure out exactly how to take those wonderful photos with your ND filter, right?!

So, over to you: Have you ever used an ND filter? Have you ever tried one with a circular polarizer filter (cpl)? Which brands do you generally recommend? Do you have any positive or negative feedback to share? Have you performed any specific filter tests?

See you soon,

Sylvain

It’ s sometimes difficult to make up your mind about which ND filter to choose and which ones to consider the best! I had the opportunity to test a lot of them. Recently, I also had the chance to test the new Kolari ND filters which are really great at all aspects (no vignetting, no loss of sharpness, no impact on white balance, no flare, etc.). Kolari is originally a brand that manufactures infrared filters. In short, here is a summary of what I think is the best in ND filters at the moment :

• Breakthrough Photography ND filters : from 49mm to 95mm and from 3 stops to 15 stops,
• PolarPro 77mm Variable ND Filter : 2 to 5 stops
• B+W XS-Pro Digital ND MRC Nano
• Freewell Variable ND filter : from 58 to 95mm and from 2 to 5 to 6 to 9 stops
• Kolari Pro Gorilla Glass ND filter : from 52 to 82mm and from 4 to 20 stops

Well there you are. I hope you liked this article and that you now have all the information you need for choosing the correct ND filter to suit you and your camera for those long exposures you desire. Now it’s time to figure out exactly how to take those wonderful photos with your ND filter, right?!

So, over to you: Have you ever used an ND filter? Have you ever tried one with a circular polarizing filter (cpl)? Which brands do you generally recommend? Do you have any positive or negative feedback to share? Have you performed any specific filter tests?

See you soon,

Sylvain