When I’d perform a camera package checkout as a camera assistant, if there was any chance that we’d be shooting outside during the day, guess which filters I would add to the order? Neutral Density filters (aka NDs)! Even if they were not part of the original order, any production office coordinator (P.O.C.) worth their salt would approve this addition by the A.C. Read on to discover why, next to a polarizer, these are the filters most essential to your video shoot.
ND Basics
Neutral: meaning there’s no effect on the color of your image + Density: the intensity of the reduction in exposure = Neutral Density. For an excellent explanation of ND filters, including a handy chart listing ND densities, read this Guide to Neutral Density Filters (for still photography), by Todd Vorenkamp. Cinematographers refer to NDs by their Optical Density Number, still photographers more often use the Filter Factor Number. For video or cine-style use, ND 0.3, ND 0.6, ND 0.9, ND 1.2 (in common parlance, “ND3, ND6, ND9, ND 12”) are the most popular, offering corresponding 1, 2, 3, and 4-stop reductions in your exposure.
Neutral Density filters come in three basic varieties: Solid ND filters, Variable NDs, and Graduated NDs. “Solid” NDs have a consistent density level from edge to edge. Variable NDs are constructed of two pieces of glass sandwiched together with a scaled ring that you rotate to produce different levels of intensity. Graduated NDs come in horizontal and vertical orientations but, for video use, you’ll probably only be using Horizontally Graduated NDs. Hard Edge NDs have a defined transition line, Soft Edge NDs offer a gradual, central transition from clear to dark, and attenuator or “blender” NDs spread the transition from clear to dark across the entire filter.
1. Shallow Depth of Field
As the images above demonstrate, NDs are helpful when you want to create shallow depth of field or blurred backgrounds even when shooting in bright light and/or with a wide lens. Start your ND kit with a single filter like this Tiffen 4 x 5.65" ND 0.6 or choose a kit like Tiffen’s 82mm Digital ND Filter Kit (2, 3, 4-Stop).
2. Exposure Compensation for Skies/Backgrounds
Especially handy for shots with large expanses of sky or with an overexposed window in the upper part of your frame, graduated ND filters enable you to expose your foreground subjects properly without the background sky “blowing out.” Soft-edge ND grads make it easier to hide the transition line within your composition. Hard-edge ND grads are more suitable for stationary frames or shots where you can hide the transition along the horizon, a roof line, window frame, etc. Attenuator NDs like the Schneider 4 x 5.65" 0.6 Attenuator Filter forgo any discernible line, instead progressing from clear to maximum density across the entire span of the filter. For advanced use, a geared filter tray like this ARRI F2 4 x 5.65" Horizontal Filter Frame (Geared) and a compatible matte box will enable you to adjust the filter gradient position in your shot precisely.
3. Consistent Exposure
As I write, spring winds are sweeping puffy white clouds across the blue Manhattan sky. Quite pretty to look at, but requiring different aperture settings over multiple takes of a scene or during an extended shot. Here are two scenarios where an ND comes in handy to maintain a consistent iris setting and the resulting depth of field.
Fleeting Clouds or Shadows: if your exposure is changing during the take, try using a variable ND—this Tiffen 82mm Variable ND features a scaled, rotating ring and it will fit a variety of cine-style primes with an 82mm filter thread. The Lindsey Optics 138mm Variable ND features 2 to 8 stops of reduction and geared thumbwheels for smooth manual adjustments or optional motor control. This filter’s 138mm round center covers all but the largest lenses’ front elements and its 4 x 5.65" frame will fit many popular matte boxes—but be aware that its thicker form occupies two filter slots.
Lingering Cloud Cover: When the sun pops out after a few takes or (heaven forbid), the dawn is creeping up during your night exterior, keep a set of solid NDs on hand to match your exposure and depth of field to previous takes captured under a darker sky. Rectangular and square filters can be stacked in multiple stages and are easier to swap in and out of a matte box than screwing on a round filter, but of course, you can use a round, variable ND here, as well.
4. Blurred Motion Effects
ND filters can be used for blurring continuous motion like flowing water, passing headlights, or motion in sports or live performances. The longer your shutter speed and the lower your frame rate are, the more evident the blur, so in brighter light, you can use a lighter ND and a slower shutter speed to capture that blur while stopping down your aperture for a decent amount of depth of field. For blur with shallower depth of field, select an even slower shutter speed and open your aperture after adding a heavier ND. Denser ND filter options include the 6-stop LEE Filters 4 x 4" ProGlass IRND 1.8, the 8-stop NiSi 4 x 4" Nano IRND 2.4, and the Schneider 4 x 5.65" RHOdium Full Spectrum ND 3.0 filter with a robust 10 stops of exposure reduction.
5. Smooth Drone Video
Use an ND filter to lose the choppy look that drone footage can have when shooting with generous amounts of light and short shutter speeds. By reducing the light that’s reaching the sensor, an ND filter enables you to select longer, cine-style shutter speeds for smoother motion. The array of drone filter kits available at B&H include the DJI 4-Pack ND Filter Set for its DJI Mavic 2 Pro quadcopter and the Freewell Day Filter Bundle for Mavic Mini with three NDs and one polarizer. A variable ND like this Aurora-Aperture 36mm PowerXND 2000 for Inspire Quadcopters offers a range of stop reduction in a single filter. For more on how filters can improve your drone videography, be sure to read Benefits of Filters for Drone Photography, by Shawn C. Steiner.
When choosing your ND filters, bear in mind that higher-end models tend to offer better color rendition, consistent density, and durability than less expensive filters. To reduce potential infrared contamination of your digital imaging sensor, try an “IRND” filter—available singly or in bundles like these 4 x 5.65" Formatt Hitech Firecrest ND 0.3 to 0.9 and ND 1.2 to 1.8 three-filter kits.
How many NDs have you ever stacked in front of your lens, and for what kind of shot? Let us know below and explore the wide variety of ND filters available on the B&H Photo Website. Whenever you’re in New York, be sure to visit us at the B&H Photo SuperStore.
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