Freewell Sherpa Variable ND Filter Review
How do you get the best image out of your smartphone camera? You need to have the right settings, and that’s not always possible if you’re using only your phone. Today we’re going to take a look at the Freewell Sherpa Variable NDs and see if these are the silver bullet to getting the best images.
No matter what camera you’re using, you should understand the different settings you can control in order to get the best looking image. If you’re filming with the stock application on your phone, many of these settings are handled for you automatically. But if you want maximum control over your video quality, you need to make sure your shutter speed, aperture, and ISO are all set at the right levels. I’m not going to dig too deep into each of these settings on this video, but VERY simply put all three of these settings impact the brightness of your image as well as the amount of the image that’s out of focus. You can get full control over these settings if you’re using an app like CinemaP3 or FilmicPro, but regardless of how you’re filming, today’s tool will help you to get the best settings on your phone.
The issue with these settings is that if you’re filming outside on a bright sunny day, the ONLY way your camera can get any image is to move these settings to a spot where more is in focus, which means you’re losing a bit of that film look. Sure, you can possibly use “Cinematic Mode” if you’re filming on an iPhone, but that’s not a great solution for video where people are moving around fast. I find cinematic mode works best if I’m just filming a talking head video with little movement, and even then it sometimes can have issues. The best way to get that shallow depth of focus is to set your aperture as wide open as possible, but if it’s sunny out then your image will end up just being a bright blob of light.
So what’s the solution? An ND filter. You can basically think of an ND filter as sunglasses for your camera. If you go outside on a bright sunny day, you end up squinting until your eyes finally adjust. Your camera has the same issue, but the problem is that the only way your camera can adjust is by changing it’s settings to a setting that puts more in your image in focus. It changes the shutter speed, which means the image will look a bit more jumpy, and it changes the aperture, which means more is in focus. If you use an ND filter, though, your camera has a better chance of putting these settings at the correct spot. For reference, you usually want your shutter speed to be double your frame rate, and your aperture to be as low of a number as possible. These rules aren’t absolute, but they’re a good rule of thumb.
Freewell Variable ND Filter
Enter the Freewell set of variable ND filters. These are two variable ND filters that are optimized for use with either an iPhone or Samsung phone, specifically on their Sherpa line of phone cases. They offer two separate variable ND filters, a 1-5 stop filter as well as a 6-9 stop filter. Essentially a variable ND filter means that you can adjust the strength of the filter to fit the amount of sunlight. Just a little sun peaking through the trees? Maybe you can get away with 1-3 stops of ND. Sun is out in full force? You may need to pull out the 6-9 stop filter.
Just a note - these filters were NOT sent to me by Freewell and were instead purchased on my own. The biggest feature that initially sold me on the Freewell filters is that they connect magnetically to your smartphone. Previous filters I’ve used either clipped onto the phone using a clip, or they connected via a plastic mount. While both of those filters had their own strengths, I found they were often more clumsy than anything and I’d spend more time trying to get them set instead of filming. The Freewell filters connect firmly, and I used them heavily on a recent project and not once did I have any issues with them coming off.
Both filters include clear markings indicating what level of ND you are currently applying. The filters twist smoothly, but are still tight enough that you’re not in danger of bumping them to change the strength. They include hard stops at either end of the filter, preventing the vignetting issue you run into with many variable NDs.
The filters are designed to be “future proof,” allowing you to remove the base if there are any significant changes to the camera design on the phones. Obviously time will tell if this holds true as Apple and Samsung continue to improve upon their cameras, but I appreciate that Freewell is at least considering how they can minimize waste and allow people to not need to buy an entirely new system with each new phone system.
Finally, the filters include a plastic case for storage as well as a rubber lens cap to protect the filter. The only thing I wish they included was some sort of rear cap so I could drop the filter into a sling without needing to deal with the slightly bulky plastic case, but honestly that’s just me being nitpicky.
The 1-5 Stop Variable ND filter is most likely the main filter you’d want for your kit. Strong enough to handle most levels of sunlight, but also low enough that you can utilize it when you just need a slight amount of relief from the sunlight. Freewell claims that these filters are designed to reproduce the most accurate colors of any filters on the market, and I have to say they do a solid job. The filters have a great look to them and allow you to set your settings exactly where you need them.
Freewell Sherpa Case
The majority of higher end ND filters I’ve used all require that you use a proprietary phone case, and the Freewell filters are no different. The Freewell Sherpa is the line of cases designed to work with these filters, offered both for iPhones 13 and 14 as well as the Samsung S23. I’ve been working with the iPhone 14 Pro case, and I have to say I’m honestly impressed. The case has a solid feel to it, and I can attest to it’s strength. I’ve unfortunately dropped my phone a few times since picking it up a few months ago, and it still looks good as new. The front has a slightly raised lip around it to protect the screen from any direct hits on the ground.
The sides of the phone are made of what feels like a rubbery/plastic feeling, while the back is a solid piece of plastic. The rear of the iPhone model includes Magsafe compatibility, so you can still charge your phone using a Magsafe charger or utilize any number of other Magsafe accessories. The buttons on the side have a nice click to them, giving you clear feedback when you push them. They also have more of a metalic feeling to them, giving the case a slightly more premium feeling. There is also a small spot where you can attach a wrist loop if you’d like a bit more security. The location of this was a great spot, as often I find that companies put these loop attachment spots on the bottom of the phone which can interfere with certain chargers or phone stands. This one close to the bottom, but located on the side so it stays out of the way.
Finally, the biggest selling point, the metallic filter mount on the back of the phone. The lens area is made of a metallic material, which allows the variable ND filters to attach to the phone. This lens cover is slightly raised, which also protects each of your camera lenses from drops and falls. To attach the filters, you just line up the logos and connect the filter. Once it’s lined up, it clicks right into place.
I have to say that I’ve been incredibly impressed with this case. It has a premium feel, but comes at a VERY affordable price. The case is durable, yet not bulky. It feels great in the hand while giving a significant amount of utility. I was prepared to use this case only when I needed to utilize the filters, but honestly it’s become my favorite case I’ve ever used on a phone.
Before jumping into the tests, if you’re interested in continuing to learn more tips and tricks on storytelling on your Smartphone, make sure you like and subscribe! In the future I’m planning to do a deep dive into CinemaP3 and explore how you can best utilize that app, in additional to covering techniques and walkthroughs on how to best capture all the elements of your stories.
Testing
To test out the filters, I took my lovely model into the back yard during the brightest and hottest part of the day. Thankfully, the heat index was only 110 degrees, so you know, just a walk in the park. The overall lighting is NOT one I’d recommend for a typical talking head, but I used this spot to showcase the impact of a full sun on overall camera settings.
First, I wanted to explore using the filters with the stock application. The settings were 4k at 24fps, but not using ProRes video. I let the phone have full control as I shot, only setting my focus and the level of the ND filter. You’ll see that the phone makes a few adjustments throughout, but overall you’re able to see how the ND filter interacts with the phone’s image.
Next, I did a similar test on CinemaP3. For this test, I set all of my settings to the ideal settings for filmmaking. 24 frames per second, 1/48 shutter speed, and the lowest ISO I could get since I was outdoors. This test shows why the ND filter is important. You can see how the image goes from significantly over exposes at first to ideal as I tested each filter and ND setting. I hit the sweet spot for these settings around 7 or 8 stops.
Next, you can see how the ND filter interacts with Cinematic Mode on the iPhone, both filming without the ND filter as well as with it. I noticed that the shadows look much nicer with the ND filter, but since it was 8 stops of ND filter it has a slight color shift that I don’t love. Ideally I would have jumped down to 7 stops where the color shift is much nicer, but it was hard to tell in the moment.
Finally, here’s the real test. I filmed footage of my wife waving in 60fps, then slowed it down to 24fps in my editor. This gave me some nice slow motion footage, but more importantly it allows you to see how the shutter speed interacts with the motion blur. First I wen through each of the stops using the stock app. You can see how the motion blur gets smoother as I increased the ND filter and the phone was able to adjust the shutter speed.
Then, I once again set the settings to the optimal spot - 60fps with a 1/120 shutter. The only difference is that this time I let the phone set the ISO levels on it’s own, since I wasn’t worried about it ever setting my ISO to a level that was too bright. You’ll notice on these how the motion blur is much smoother, and it’s more just a matter of me dialing in the correct amount of ND to control my lighting.
Results
Overall, I love these filters. An ND filter allows you to set your camera exactly where you’d like it, and if you’re using the stock app then the phone has at least a fighting chance of hitting the right settings. In terms of quality, the impact these have to the color overall is great at the lower stops, and I found that they introduced a healthy amount of softening to take just a bit of the digital edge off the phone’s look. The biggest issue I ran into is that they lose a bit of quality if you utilize the 1-5 stop filter at 4-5 stops. 1-3 stops have little to no impact on the overall color of the image, while 4-5 stops starts to introduce a slightly orange hue to your image. Meanwhile, the 6-9 tends to get that color cast at 8-9 stops.
The filters also meant that my camera had a fighting chance getting the best settings at 60fps to give me better looking slow-motion footage. The reason shutter speed matters is because that affects the amount and look of the motion blur in your shots. It’s not as obvious at 24fps, but as soon as you slow it down then a shutter speed that’s off will be more noticeable. I often find myself filming b-roll at 60fps to slow down in post, so that makes shutter speed even more important.
Regarding the very slight color shifting in some of the settings, I’d be interested to see if this can be minimized using an app like CinemaP3 where you can add tint to your white balance and slightly shift the overall color. I didn’t get a chance to play with this in my initial testing, but it’s something I plan to use in the future.
In a real world usage of these, I’d say that you can safely use the VND 1-5 at 1-4 stops, but if you need to step it up to 5 stops then make the jump to the VND 6-9 at 9 stops. Then, I wouldn’t go beyond 7 stops and just make adjustments to your shutter if you need to. This will give you the least amount of color shift while allowing you to stay as close to optimal settings as possible.
Other Accessories
I wasn’t able to test out the other accessories in the Sherpa line, but Freewell has a number of other accessories that can extend your creativity. They offer both the Varabiable ND filters in a mist variety, giving them a bit more of a softer vintage look. Similarly, they offer both a snow mist and glow mist filter to soften your footage and give them a vintage look in different ways. Additionally, they have a circular polarizer, which can help to minimize reflections on windows and water.
If you want to get even more creative, they offer anamorphic lens sets that create either blue or gold flares if you’re wanting to channel your inner JJ Abrams. These anamorphic lenses include their own snap on ND filters as well, and the lenses snap directly into the case over your lenses.
Finally, and the item I’m most excited to try out, is their bluetooth grip. I’m a big fan of using grips when filming in landscape mode on my phone, but I’ve found the two I typically use get in the way of these variable ND filters. Enter the bluetooth grip. It clips onto the phone on one side and gives you a more traditional grip similar to a higher end camera. Additionally, it provides a bluetooth connection where you can remote trigger your recordings. Finally, the base can extend out into more of a selfie stick if that’s something you’d want to try out.
Just saying, Freewell, I’d be happy to review these if you send them my way!
The Freewell Sherpa case and variable ND filters are a great tool to have in your tool belt. The speed of use and overall quality means you can set your phone settings exactly where you need them. Even if you’re using the stock application and allowing it to handle your settings, the only way the phone can hit the optimal settings in certain scenarios is if you use some sort of ND filter. Are these perfect? Of course not, but few tools are. But considering the overall price of the filters and case, you’d be hard pressed to find a better option on the market. These aren’t a necessity of storytelling, but they are an additional tool that can help to improve the quality of your filmmaking. If you’re interested in learning techniques and tips for telling stories on your smartphone, make sure you subscribe! And as always, remember, it’s not about the gear, it’s the story that matters.
