Why Video Needs a Variable ND Filter
When you shoot video outdoors on a sunny day, your camera's shutter speed is locked to your frame rate (typically 1/50s at 24fps) to avoid flicker and maintain natural motion blur. Without a neutral density filter, even the smallest aperture may let in too much light, forcing you to raise the shutter speed and ruin the cinematic look.
A variable ND filter solves this by letting you dial in the exact amount of light reduction without carrying a stack of fixed ND filters. The Marumi DHG Variable ND2-ND400 filter, for example, adjusts continuously from ND2 (1 stop) to ND400 (over 8 stops) by rotating the filter ring—similar to how you'd use a polariser.
Setting Up Your Variable ND Filter for Video
The following steps assume your camera is on a tripod or stable surface and you have the correct filter size for your lens.
- 1. Find your lens thread size: Look on the front of your lens for the symbol ɸ followed by a number in millimeters (e.g., ɸ72). That number is the filter size you need. The Marumi DHG VND is available in 49mm, 55mm, 62mm, and 72mm variants.
- 2. Screw the filter onto the lens: The ultra-thin aluminium frame screws directly onto the lens thread. Avoid overtightening; a snug fit is enough.
- 3. Set your camera exposure manually: Choose your aperture (often wide open for shallow depth of field) and set the shutter speed to double the reciprocal of your frame rate (e.g., 1/50s for 24fps). Keep ISO as low as possible.
- 4. Rotate the filter to dial in the right density: While looking at your camera's live view or histogram, slowly rotate the filter ring. You'll see the image darken smoothly from ND2 to ND400. Stop when the exposure meter shows a correct reading.
Marumi DHG VND Filter Key Specs
- DHG Variable Neutral Density (VND) Filters: The Marumi DHG Vari ND2-ND400 filter allows continuously variable light adjustment from ND2 to ND400 by rotating the filter. One filter replaces a whole set of fixed ND filters, saving weight and time during outdoor shoots.
DHG Variable Neutral Density (VND) Filters - DHG Variable Neutral Density (VND) Filters: The filter enables the photographer to use lower shutter speeds under very bright sunlight without altering the colour tone of the picture. Colour neutrality is critical for video; you don't want a colour cast that requires grading correction later.
- DHG Variable Neutral Density (VND) Filters: Japanese optics and original light reducing material construction. The optical quality helps maintain sharpness and contrast, which is especially important when stacking multiple glass elements.
What the Variable ND Does Not Replace
A variable ND filter controls light, not motion. It won't stabilise your shot or replace a gimbal. Also, at the highest density settings (near ND400) on some variable ND filters, you may notice a slight cross-hatch pattern or vignetting on very wide lenses. The supplied information for the Marumi DHG VND does not specify a minimum focal length, so test your lens at the strongest setting before a critical shoot.
If you need a specific density for a long exposure still photo, a fixed ND filter may still be a better choice for maximum optical consistency. For video, however, the convenience of adjusting density without swapping filters is a clear advantage.
