ND filters give you control over exposure and shutter speed in bright light. A good set of iPhone ND filters are essential in any smartphone filmmakers kit.

If you’re new to video completely you may never have heard of an ND filter before. Maybe you’ve heard and read about ND filters, but never used them. You might be a seasoned pro but are unsure how to mount ND filters on a phone camera. Hopefully, this article will answer all those questions, and more.

If you’re looking to create cinematic video with your iPhone, you’ll need a solution to mount ND filters in front of your camera lenses in order to take control of your shutter speed in bright light. ND filters evenly reduce the light entering your camera, allowing you to set a slow shutter speed even in bright conditions. A slow shutter speed is what gives you the kind of motion blur you see in movies, that you don’t ever see in smartphone video… unless using an ND filter.

Inside a speeding Dodge Challenger on a desert road.
A film like motion blur can really help how your image looks…. more like film, less like iPhone video. ND filters make this possible.

What is a ND Filter?

ND stands for Neutral Density. An ND filter uniformly reduces the amount of light passing through it in order to control exposure and shutter speed. A slow shutter speed is what gives you a film like smooth motion blur to objects in motion through the frame. It’s important that the filter reduces all visible wavelengths (colors) of light equally to prevent any color shifts in the recorded image. Some filters do this better than others, and none are perfect.

Reflective and Absorbtive ND Filters

There are two ways to reduce the light passing through a filter. You can either reflect the unwanted light away, or absorb it. ND filters can employ either of these methods. Reflective ND filters use metallic coatings to reflect a specific range of wavelengths. Absorbtive ND filters use the glass itself to absorb unwanted wavelengths of light.

Optical Density

ND filters come in different strengths, this is referred to as optical density. Optical density defines the amount of light allowed to pass through the filter. The higher the value, the less light is transmitted through the filter.

Good ND filters are made with the highest quality optical glass and coatings, so they tend to be expensive. It’s worth spending a bit more on filters that you can trust, and many come with a lifetime warranty. If you take care of them, they’ll take care of you for a long time.

Variable ND Filters

Most ND filters come in fixed densities, and so you need a set of filters to control exposure in different lighting conditions. This means physically changing the ND filter every time the light changes. However, there is another solution.

A variable ND filter allows you to change the amount of light that passes through the filter just by rotating it. They work differently to fixed density ND filters. A variable ND filter is made up of two stacked polarizing filters, one of them is fixed, the other is able to rotate. As light is polarized passing through the first filter, some of it is blocked from passing through the second depending on the angle of rotation. When both polarizing filters are aligned, light is allowed to pass through. When the front polarizing filter is rotated 90 degrees to the rear filter, no light will pass through. Between 0 degrees and 90 degrees the effective density can be changed.

The advantages of using a variable ND filter are not having to swap out filters all the time, and being able to adjust the density to any value needed. However, there are some important limitations.

Because of the way variable ND filters work, they are not suitable for lenses with a very wide field of view. They also introduce what is called cross polarization when the rotation gets close to 90 degrees. This creates a visible “X” shape in the image.

Avoiding Cross Polarization

Some manufacturers solve the cross polarization issue by splitting the density range into two separate filters. Each filter will have a smaller range of density, and no cross polarization. A typical split is a 2-5 stop filter and a 6-9 stop filter. This does increase cost because you need to buy two filters to cover the full range instead of one. But, you should consider that the highest densities of a single wide-range variable ND filter will likely be useless anyway because of this issue.

Situations Where I’ll Choose a Fixed Density ND Filter over a Variable ND Filter

Most of the time I use a variable ND filter, but there are situations where I’ll break out my set of fixed density ND filters instead.

  1. Whenever using a very wide angle lens attached to the phone camera (variable ND’s cause problems with very wide angle lenses).
  2. When using a lightweight smartphone gimbal. (I’ll use my Moondog Labs ND filters… only 2mm thick and super lightweight).
  3. When using a circular polarizer filter.

Variable ND filters are more expensive than a single fixed density ND filter, but you only need to buy one, or two instead of a set. I use the pair of PolarPro Peter McKinnon Edition Variable ND Filters and highly recommend them.

Motion blur plays a big part in achieving cinematic video. This is a video frame grab shot with the iPhone 7 Plus and the PolarPro Iris ND filters.

Why Use a ND Filter?

One of the factors that influences the look and feel of your video in a subtle but important way is how motion is recorded. A natural looking blur of objects in motion is important when you want your video to look more like motion picture film, or like it was shot with a cinema camera, and less like smartphone video. I go into this, and other factors in more detail in my guide to shooting cinematic video with your iPhone and FiLMiC Pro.

Motion blur is directly connected to shutter speed, and shutter speed is directly connected to exposure. A slow shutter speed gives you a longer exposure and more motion blur, but the longer exposure can mean an over exposed image.

In order to maintain correct exposure with a slow shutter speed in bright light, you have to reduce the amount of light entering your lens. This is exactly what an ND filter does.

IR Pollution and Color Shift

Camera image sensors are sensitive to more than just visible light. They can also pick up invisible light, especially infra red. Infra red light is emitted by many light sources, including the sun. Most camera manufacturers build IR filtration into their cameras, but some don’t.

If an ND filter only reduces visible light, but lets IR pass though unaffected, you may see an obvious color imbalance if your camera image sensor doesn’t have built in IR filtration. This is called IR pollution.

An IR pollution issue is easy to see. Shadows and dark areas of the image will look brown and muddy. Other colors will be affected as well. IR pollution is very difficult to correct in post production.

I haven’t seen a problem yet with IR pollution when shooting with a smartphone, so I assume most, if not all smartphone cameras have built in IR filtration.

Many ND filters are full spectrum filters in any case and are designed to reduce IR wavelengths along with visible light. Look out for the terms IRND, or full spectrum when choosing ND filters.

Correcting ND Filter Color Shift in Post Production

As long as an ND filter doesn’t introduce too much color imbalance, and you’ve set and locked white balance correctly in your camera app, it’s possible to correct color imbalances manually in post production. The only way to do this perfectly and consistently is to shoot a color chart, and use it to color correct in post. You can learn how to do this in DaVinci Resolve with my tutorial Shoot and Color Grade FiLMiC LogV2 with the X-Rite Colorchecker Passport Video.

It’s safe to assume you’ll always need to color correct when using any ND filter, which is a good reason to use a color chart such as the X-Rite ColorChecker Passport Video when shooting. It takes all the guesswork out of color correction in post.

ND Filter FAQ

I’ve tried to answer some common ND filter questions below. If you have a question which isn’t covered, please contact me and I may add it.

What do the filter ratings mean?

There are two common ways that manufacturers use to describe the densities of an ND filter.

One is with a ND number, such as ND2, ND4, ND8 etc. and this refers simply to the ratio of light it will allow to pass. A ND 4 allows 1/4 of the light to pass. This is common with photography filters.

The second is by optical density, this will be 0.3, 0.6, 0.9, 1.2 etc. which is most common for ND filters used in cinematography.

Optical DensityND NumberTransmissionReduction (Stops)
ND 0.3ND 21/21
ND 0.6ND 41/42
ND 0.9ND 81/83
ND 1.2ND 161/164
ND 1.5ND 321/325
ND 1.8ND 641/646
ND 2.1ND 1281/1287
ND 2.4ND 2561/2568
ND 2.7ND 5121/5129
ND 3.0ND 10241/102410

How do I know if a ND filter is good?

Unfortunately, you will rarely find actual transmittance data given by manufacturers for specific products. The two most important things that should be mentioned is minimal (or no) color shift, and an IR coating.

Typically the more expensive the filter, the better it will perform, although price isn’t always a determining factor. It is also worth looking for independent user reviews.

How do I attach a filter to my external lens?

Many popular iPhone lenses also have filter adaptors available. A filter adaptor may not come with the lens, and may have to be bought separately. Look for the filter thread diameter that matches the lens filter adaptor.

The links in the table below are affiliate links.

LensSeparate Filter Adaptor RequiredFilter size
Moondog Labs 1.33X Anamorphic Lens (All Versions)Yes52mm
Moment Wide 18mm LensYes62mm
Moment Tele 58mm LensYes62mm
Moment Fisheye 15mm LensYes62mm
Moment Fisheye 14mm LensYes (Coming Soon)62mm
Moment Macro 10X LensYes62mm
Moment 1.33X Anamorphic LensYes62mm
Beastgrip ProSeries 3X Tele Conversion LensNo58mm
Beastgrip x Kenko Pro Series 0.75X Wide Angle LensNo58mm
Beastgrip Pro Series – 1.33X Anamorphic LensNo58mm
Beastgrip M Series 1.33X Anamorphic LensYes58mm
Beastgrip M Series 0.6X Wide Angle LensYes58mm
Beastgrip M Series 2X Telephoto LensYes58mm
Beastgrip Wide-Angle Lens with MacroNo49mm
Zeiss ExoLens Pro WideNo40.5mm
Zeiss ExoLens TeleNo40.5mm

I don’t use any external lenses, can I still use ND filters?

There are now a few good ND filter systems available for mobile filmmakers that fit directly over the phone camera lens. I have been using the PolarPro Iris filter system for some time and love it. It even fits over the wide and telephoto cameras on the iPhone 11 Pro and Pro Max. Sadly, it seems that PolarPro are no longer making the Iris system.

However, they have recently launched the PolarPro LiteChaser Pro. The LiteChaser Pro is a case mounted filter system that accommodates a set of proprietary filters. These filters range from fixed ND filters to a variable ND filter, and a circular polarizer. They are available in various kits that include some filters, and the filters are available separately also.

If you have a metal cage or a case with a threaded lens mount, then you can use one or more step up rings to mount standard circular photographic filters over one or more cameras depending on the cage. A common size threaded lens mount is 37mm.

My favorite lightweight filter solution for the iPhone 11 Pro Max is the Moondog Labs Multi Camera Filter Mount. It provides a standard 52mm filter thread, and is compatible with all iPhone 11 models. It will cover all three cameras on the iPhone 11 Pro and iPhone 11 Pro Max.

How do I know which density ND filter to use?

When shooting video in bright conditions you will usually aim to keep your shutter speed value at double your frame rate. For example, if your frame rate is set to 24fps, you’ll aim for a shutter speed of 1/48th second.

You can calculate which ND will reduce your shutter speed easily by dividing the auto shutter speed value by two until you reach close to your desired shutter speed. Count how many times you had to divide, and you’ll know how many stops you need to reduce.

In bright direct sunlight, you will usually need a 6-7 stop reduction, which is a ND64 (Optical Density 1.8) or ND128 (Optical Density 2.1).

ND filters are useful in very bright conditions to control exposure even when there isn’t a lot of motion in your shot.

ND Filters are Essential Accessories

A set of ND filters are an essential part of your filmmaking kit. Being able to control shutter speed and achieve cinematic motion blur in your shots will bring a big camera quality to your smartphone videos.

If you’re interested in learning about other key technical and creative factors that will improve the cinematic quality of your videos, I recommend reading my guide to shooting cinematic video with your iPhone and FiLMiC Pro next.

iPhone ND Filter Reviews

I’ve started testing fixed ND and variable ND filters from various manufacturers. So far I’ve begun with the Beastgrip Pro Series ND, VND and CPL filters. I will also be putting my other filters through similar tests and writing up full reviews for each set. These reviews will eventually cover the Moment VND filters, the PolarPro Peter McKinnon Edition VND filters, Freewell VND filters, and the Moondog Labs (Nisi) ND filters. They will also all be added to my gear page. So bookmark this page if you want to come back later to check or better yet subscribe to my very occasional email updates.

Further Reading

Stay in Touch

If you’d like to be notified of new articles and tutorials you can subscribe to my very occasional email updates.

Please don’t hesitate to comment with your questions either here, on Youtube, or hit me up on twitter, I will always reply.

31 Comments

  1. Richard,
    Love the site,I’ve learned a lot,however I am going to have to go over the color correction tutorial a few times.
    I use the iPhone 11 Pro along with Filmic Pro. I bought the Polar Pro kit but it only has the 3-5 VND filter. After reading your article on ND filters Im certain Ill be needing something else in bright sunlight but have no idea as to what.
    Polar Pro also has the ND 8 and ND 64,what do you think?,,will this be sufficient?

    Thanks
    Richard

    • Richard Lackey

      Hi Richard, yes in bright sunlight you’ll want a stronger ND filter. I live in Dubai, and it’s nothing but sun every day of the year pretty much. I use 8-stops of reduction most often, this is an optical density number 2.4, or a ND256, which is two stops stronger than a ND64. You are using the Litechaser Pro?

      • Richard,
        I am using the Litechaser Pro,thanks for the tips,,and once again I quite appreciate your site.I envy your year round sunshine…

  2. Thank you for this informative article. I had a quick question would a 62mm VND work for a iPhone 12 Pro Max without getting vignetting? Especially on the ultra wide angle lens. Thanks

    • Richard Lackey

      Hi Amit, I haven’t tried any ND filters with the ultrawide camera, 62mm size should be fine, it’s more than large enough. I definitely would avoid a variable ND filter on the ultra wide camera, rather stick to a good fixed density ND filter. How are you mounting it to the phone?

      • I was looking to buy this
        https://www.amazon.com/gp/product/B08BVZH8XG/ref=ox_sc_saved_title_9?smid=A1GLZMDF7560DH&psc=1
        but the 62mm version. Thanks for your reply

      • Hi Richard,
        Due to the pandemic I have a lot of time on my hands and want to start experimenting with filmmaking (shooting, writing, producing, etc.). I am definitely a beginner but not exactly an idiot when it comes down to this stuff! Like most people I decided to dive into looking at start up gear and of course I am completely overwhelmed!!! The funny thing is is that I know the most important part about filmmaking is how you visually tell your story. So rather than invest in the latest high end stuff like the Blackmagic pocket cinema camera or the LUMIX S5 I’ve concluded that it makes sense to start with what I have (the iPhone). Your articles are very informative. Thank you! I’m wondering if you have any online classes (or in person depending on where you are) that teaches how to master the iPhone as a cinema camera? I am very interested shooting stuff that looks like a film or movie rather than a crystal clear home video. Ideally I would like to get geared up with everything I need to get started with an iPhone, play around and master the equipment before I purchase or move up to anything else. I anticipate this may take a while. I know there will be limitations as I get more advanced but I believe that will just help me be more creative as opposed to running out and buying more gear. Some of information I want to learn involves:
        Editing software
        iPhone camera apps
        Rigs
        Lights
        Audio
        Filters
        ***How and why I should shoot a scene a certain way***

        Any advise or guidance will be greatly appreciated!

  3. Hi Richard, thank you for this article it was very helpful. I am new to mobile videography and the only question i had is do you think a 62mm VND would be too small to cover all three lens on an iPhone 12 Pro Max? I am just concerned about vignetting especially on the ultra wide lens. Thank you.

    • Richard Lackey

      I just replied also to your other comment. Yes, I think it will be large enough. I recommend you take a look at the Moondog Labs Multi Camera Filter Mount for the iPhone 12 Pro Max.

  4. Hi Richard,
    First of all, thank you for your guides and YouTube videos. They are the simplest and most comprehensive beginner’s guide I have found on iPhone filmmaking.

    I was wondering what your recommendation of an ND filter for my Moment iPhone anamorphic lens. I have a 67mm ND mount for the lens. There are other mounts available, but that is the one I have. In your guide, you wrote to not use Variable ND filters on wide angle lenses. Does a wide angle lens mean an anamorphic lens? (I think yes, but just double checking). If so, which ND filter set should I get for iPhone filmmaking?

    Thanks for your time!

    • Richard Lackey

      Hi Owais, thanks for the feedback! I’m glad you find my ramblings useful. I also use 67mm filters, and have found some variable ND filters that work just fine on wide angle lenses. Fixed density ND’s will give you the best uniformity, but VND’s which have a limited density range (such as sets that are split into two filters… 2-5 stop and 6-9 stop) do not suffer from the same issues as single VND filters that try to give a wide density range in a single filter. I recommend the 2-5 stop and 6-9 stop pairs of VND’s from PolarPro (the PolarPro Peter McKinnon Edition VND’s are my favorite), also the Moment VND filters, and the best value for money (excellent optical performance for the price) are the Freewell VND filters. All of these are a set of two, coming in 2-5 stop and 6-9 stop filters.

  5. Brittany Diane Daniels

    Which ND Filters (Both variable and single NDs) would you recommend for an iPhone XS to help take better architecture photography outside and landscape photography? I am asking this because I will be retaking Intro to Photography again this time online through Georgia Piedmont Technical College (GPTC) Clarkston, GA Campus.

    • Richard Lackey

      Hi Brittany, out of the variable ND filters my favorites are the PolarPro Peter McKinnon Edition VND’s, there are two strengths, a 2-5 stop and a 6-9 stop, however they are pricey. Second to this, both the Moment variable ND filters, and the Freewell variable ND filters are excellent too and less expensive (also split into two, a 2-5 stop and a 6-9 stop). Fixed ND filters there are many good ones. I like the Beastgrip ND filters, and also the Nisi ND filters are very good. I have some that came from MoondogLabs, which are made by Nisi, and they are super thin and light and excellent optical quality. Tiffen also are a industry standard, and you can’t go wrong with them either.

      Do you have any existing case for your iPhone XS that has a lens mount on it? Let me know, I can help recommend one if you don’t, along with a filter mount to actually mount the filters.

  6. Brittany Diane Daniels

    What ND Filters (both Variable and Single) do you recommend for taking better landscape photography and better architecture photography outside for an iPhone XS? I am asking this question because I will be retaking Intro to Photography that is through Georgia Piedmont Technical College (GPTC) Clarkston, Ga Campus that will be taught online in the upcoming Spring 2021 semester.

  7. Hi, can you also recommend a ND or VND filter in combination with a DJI OM4 ? I have the gimbal and am now looking into which cases or clip-ons plus filters work best with it.

    • Richard Lackey

      Hi Art, which phone are you using? You’ll want something lightweight, and you may require a counterweight also. I am enjoying the Sandmarc Hybrid filters, which combine an ND with polarizer, but these are fixed density ND’s not a variable ND. The kit comes with a ND16, ND32 and ND64 and the clamp on mount. https://www.sandmarc.com/products/hybrid-nd-pl-filters-iphone Although to be honest, I find an ND64 is still not strong enough in bright sunlight. I will make a review of this kit soon. Sandmarc also make a variable ND https://www.sandmarc.com/pages/iphone-variable-nd-filter although I have not tried it.

      Which phone are you using? I am sure I can make some better and specific suggestion if you can come back to me with this info.

  8. Gustavo Lopez

    Hi.
    First of all I`d like to thanks for writing such a complete review. Great job.
    I am currently filming with this Apexel Anamorphic which works quite good: https://www.shopapexel.com/collections/anamorphic-lens/products/anamorphic-lens-for-smartphone. It would be very nice to know if there´s any way to mount an ND filter using an adaptor. If you have any recommendation I will really appreciate it.
    Best regards,
    Gustavo

    • Richard Lackey

      Hi Gustavo, I hadn’t seen this lens before. It looks interesting. I took a look at the link. It look to me like unless they make a specific filter adapter for this lens, I don’t know of anything else that will fit.

  9. I agree with you

  10. Willis Medling

    I agree with you

  11. Martin Muchna

    Hi Richard. I use Moment 67 mm filter mount with variable ND filter on iPhone 11 Pro. In bright sunny days, there are lot of orange/brown flares in the left corner of the recorded video. So the video is damaged. It is definitely a not color shift you mentioned in this article. I have 2 variable ND filters (Moment one and cheaper one) and with both I have the same problem. Could it be caused only by angle I shot or something else? Is possible to use sun shade / shield with iPhone and ND filter? Thanks!

    • Richard Lackey

      Hi Martin, that’s interesting, it could definitely be a flare of some type caused by the angle to the sun. Do you see this all the time? or only when facing at certain angles to the light?

  12. Pls what size of filter would be ideal for Sirui lenses

    • Richard Lackey

      Which Sirui lenses do you have? As far as I can see, I don’t think they have filter threads on the front. It may not be possible to mount filters unless Sirui make some kind of a separate filter mount.

  13. Thanks for the great advice, also in your Youtube videos.

    I have a question though:

    I sold my DSLR and now only shoot with my iPhone 11 Pro Max. I also own the Moment Tele and Wide lens. I bought a Neewer variable ND filter, but am not happy with the quality. So I’m following your advice and looking at the Polarpro Variable ND Filter combo. However, before making a purchase decision, I will wait what PolarPro will present for the iPhone 11on February 18th.

    In case I go with the Polarpro Variable ND Filter combo, what size should I get (67mm, 77mm, 82mm)? I will need to use a step-up adapter with the moment filter mount anyways. After some checking I think 77mm is my best option, as this is the most common size (making it easier to sell it later). Or should I got for the 82mm, simply because it is the largest? The price is the same.

    What do you recommend?

    • Richard Lackey

      Hi Stefan, I think waiting to see what’s coming up is a good idea.

      I use the 67mm size PolarPro VND’s and various step up rings depending on what I’m mounting them on. The thing I like is how flexible this is, with the right step up ring I can thread it onto pretty much any lens. I now have the Beastgrip wide and tele, which have 58mm thread. There’s something coming up from Moondog Labs too which will make it easier to use a VND on the 11 Pro Max.

      I’d wait a bit. There are some interesting options coming up that might affect your decision.

  14. Great explanation. Honestly broke it down better than any other article I’ve read. Thank you

    • Richard Lackey

      Wow, thanks so much! I always have doubts about whether I’m making any sense. Glad it helped. Don’t hesitate to ask any questions, I always try to respond even if I don’t know the answer.

  15. Do you think there is going to be a difference between a good Variable ND such as Gobe (3 peak version) and a stand alone ND filter on an iPhone?

    • Richard Lackey

      It all depends, it’s often a trade off. A variable ND is a really flexible tool to have but some of them can introduce unwanted visual artefacts especially when used towards the extreme of their density ranges. A fixed density ND filter doesn’t have these problems but you need a set of them and have to physically swap them under different light conditions. I am not familiar with the Gobe variable ND’s but in general I would avoid any variable ND that attempts to cover too wide a range. The 3 peak 8-128 is probably the one I’d be most interested in.

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