Guide to Cinematic ND Filters 2021
- June 9, 2021
- Hurlbut Academy
When you’re just starting out as a cinematographer, understanding filters can seem a bit tricky. With all the different kinds of filters out there, it’s easy for filmmakers to slip up and use the wrong kind — or worse yet, fail to use one altogether. Especially when it could have enhanced your shot. Neutral Density filters (otherwise known as ND filters) are some of the most common filters and come available in all shapes and sizes, including both plastic and glass.
In this article, we’re going to dig into the finer details of ND filters so you can make the best possible decision for your camera kit. With that in mind, let this serve as your guide to Cinematic ND Filters 2021.
Here’s some of what we’ll explore.
- What does an ND Filter do?
- ND Filter Reference Chart
- Why Use ND Filters?
- Tiffen Straight NDs
- Tiffen IR ND Filters
- Water White Straight ND Test
- Tiffen Black Diffusion
What does an ND Filter do?
At its most basic form, neutral density filters allow you to control the light that enters your sensor. Think of it much in the same way sunglasses work over your naked eye. Filters help you see more clearly and expose for more texture and details, while not affecting your color. And, that’s precisely what inspires the “neutral” in neutral density.
However, even though the color should remain neutral, there are NDs that experience color shifts that you can use to your advantage, like greens, cyans, and magentas. But even if you’re shooting in black and white, NDs are still useful for establishing more texture and achieve the same benefits as you would shooting in color.
What’s the difference between photography and cinema ND filters?
Both in photography and cinematography, NDs are used to mitigate overexposure and image brightness. But, in photography, you can also adjust your shutter speed to make it shorter. What makes neutral density so important for cinema is how it controls the light separately from your camera and lens.
When shooting with a motion picture camera, you have a Base ISO, a required shutter (almost always 180 degrees unless looking for a special effect), and your Lens T-stop. The Lens T-stop is important to maintain the same depth of field throughout shooting conditions so that you are exposing a variety of shots at the same level. In filmmaking, you don’t change the lens and camera settings much when dealing with exposure levels. Instead, you add or take away ND.
There are 3 primary types of ND filters: Solid ND filters, Graduated ND filters, and Variable ND filters.
Solid Neutral Density Filters
Solid ND filters are NDs at their simplest form, meaning that the filter is evenly coated across all edges.
Graduated ND Filters
Graduated NDs are darker on one side and lighter on the other and made available in 2 forms: Hard Edge NDs and Soft Edge NDs. The difference between the two is pretty simple: Soft Edge NDs provide a softer, gradual transition from translucent to dark, and Hard Edge NDs have a clear-cut, defined transition line.
Variable ND Filters
Variable NDs are easily adjustable and best for when you don’t have time to switch between filters. They’re comprised of 2 separate glass polarizers stacked together and with a scaled ring that you can rotate to modify the levels of intensity. These“polas” limit light coming from a certain direction and when combined together they work to limit light from entering the lens.
Why Use ND Filters?
As we mentioned above, there are a few key reasons why you would want to use ND filters for cinematic effect. Think of it this way, using an ND can be the difference between capturing a milky sky with fleeting clouds overhead, full of dramatic detail, or just a blown-out, white abyss.
Here are some of the other reasons why you need ND filters:
- Shallow Depth of Field
- Blurred Motion Effects
- Consistent Exposure
- Exposure Counterbalance for Skies
Take a look below for a list of our favorite ND filters that we’ve also reviewed! And if you need a little help finding the right filter for your lens, Tiffen offers an extremely helpful Camera Lens to Filter Chart!
Tiffen Straight NDs
Tiffen filters come in all forms, from straight NDs to glimmer glass and Infrared (IR) variants. Just like a painter has various paints and brushes for their canvas, a cinematographer needs a healthy variety of filters.
At your foundation, you’ll need Straight NDs that you can count on. To see how Tiffen’s Straight NDs perform, take a look at our side-by-side comparisons in the video below.
Tiffen IR Neutral Density Filters
Tiffen IRND filters prevent Near-IR and Infra-Red light pollution while simultaneously maintaining the appearance of your darker areas. These filters are really effective in preserving color accuracy for most cameras.
In fact, IRND filters are ideal for HD cameras since they have greater low-light sensitivity and a greater sensitivity to IR contamination. So, if you were to just use an ND filter to counter the increased light sensitivity, the IR pollution will be unavoidable.
But in some cases, such as Canon’s camera system, its optical low pass filter (OLPF) handles IR pollution well enough where you won’t require an IR ND. But with other cameras like RED Dragon and Blackmagic, you may need IR NDs on hand.
Most cameras with internal NDs are matched to the sensor with the appropriate OLPF and Color Matched NDs. So, you’ll need to be aware of cameras that don’t have internal NDs. Modern OLPFs for RED have improved in this area. There are a large number of IRND options out now, and it’s much more common.
For tests and side-by-side comparisons of how these filters work, we recommend What is IR Pollution and How Do You Combat it? for Hot Mirror IR ND filters, Straight NDs, and more.
If you want to be sure about how these IR filters work on the RED Dragon, the video test below is particularly helpful.
Tiffen NATural ND Filters
The first thing you may notice about Tiffen’s NATural NDs is their bronzed appearance, rightfully giving them the impression of the next layer of ND technology. That’s because these NDs are designed to reflect away infrared (IR) and ultraviolet (UV) contamination.
NATural Neutral Density filters use dual-layer ND elements that work in harmony to assure a clear, neutral image without any unwanted tint.
Like its other filters, Tiffen’s NATural NDs are crafted with two pieces of durable Water White glass with the brand’s signature ColorCore® technology for lasting effect.
Speaking of Water White glass…
Tiffen Water White Straight Neutral Density Filters
The Tiffen Water White Straight ND filters are designed with ‘Water White’ glass and constructed with ColorCore technology.
What this does is increase your clarity and color fidelity. Water White filters are often crafted with infrared technology to reduce IR pollution.
When out shooting during a bright afternoon with the sun high in the sky, simply snap on your Water White NDs, optimized for digital sensors.
Tiffen VariND Filters
VariNDs (Variable NDs) are used in place of multiple fixed filters, allowing you to change the amount of light entering your lens. It shares the same ease of use that you would get with a zoom lens, where you can control it just by turning it.
VariNDs are good when you don’t have a lot of time or working with shifting light and need quick versatility of control. Just like a circular polarizer (CP) filter for photographers out there, Tiffen VariND filters work by rotating one layer from the other.
However, there are some shortcomings. The VariND takes the polarizer and changes its effect. A VariND will stop doing what it normally does, which is to keep certain directional wavelengths of light from entering the lens and reduces glare or sheen from a face.
This can help make people look less shiny, but won’t work when you are using two polarizers together in a VariND system. It changes the way a pola works to make it more about cutting light off from the lens.
You won’t want to depend solely on a VariND, but it’s a good idea to have a solid one in your kit, especially if you’re a documentary filmmaker and need to move quickly.
Tiffen Black Diffusion Filters
When it comes to cinematic filters, you’ll require Black diffusion for their softening qualities that present a small, yet satisfying glow on overly sharp or well-defined imagery while still maintaining contrast – this is what the “black” in Black Pro-Mist defines.
This glowing effect is essential when painting with light and implementing more texture into your shot to avoid overly crisp, and daytime soap-looking images.
The Bottom Line
Every cinematographer should understand why and how to use neutral density (ND) filtration. The value of ND filters is priceless for crafting the most memorable, cinematic shots.
Hurlbut Academy actually offers a free course that you can access in our sampler courseware.
So, real quick, let’s review why Neutral Density filters are necessary:
- Balances your exposure
- Helps eliminate overly bright, washed-out images, or Skies
- Allows you to better control depth-of-field
- Enables slower shutter speeds for blurred motion effects (primarily a photographic effect but also sometimes used in filmmaking)
There’s an extensive variety of filters out there that you should consider implementing to enhance your filmmaking.
However, what works for your style might not work for someone else. So, be sure to try and test different NDs with your camera setup, and review as many videos as possible.
If you need more help with understanding diffusion and filtration, we also offer a super helpful course: How To Use Lens Diffusion. In this course, Shane Hurlbut, ASC takes you through the proper use of filters and clues you in on essential advice that you’ll only receive from a professional cinematographer!