Neutral Density filter with optical density 0.6, reducing light by two stops (ND4), essential for daylight filming with open apertures and proper shutter angles.
Optical Density and Aperture Value
The ND 0.6 filter (also known as ND4) has an optical density of 0.6 and reduces incoming light by two stops. This means the amount of light is reduced to one quarter.
The ND4 designation system indicates: The number specifies the factor by which the light is reduced. ND4 therefore means: light is divided by 4. This corresponds to a reduction of 2 stops (2 x halving = quartering).
Typical Applications
Daylight Cinematography with Normal to Wide Apertures
The ND 0.6 is perfect for bright daylight when you want to shoot with apertures between f/1.4 and f/2.8. With a two-stop reduction, you can still use these apertures even under intense sunlight.
Professional Motion Blur
When adhering to the 180-degree shutter rule (1/50 second at 25p), the ND 0.6 is particularly valuable. It allows you to maintain this shutter speed while preserving a cinematic wide aperture – this is the key to a professional look.
Combinability with Other Filters
The ND 0.6 can be combined with other optical filters without significantly degrading image quality. Many cinematographers stack ND 0.3 and ND 0.3 or combine ND 0.6 with color correction filters.
Difference to Variable ND Filters
Variable ND filters can cover the ND 0.6 range but have the following disadvantages:
- Color Casts: Continuous rotation often results in magenta or green color casts.
- Moiré Effects: Disturbing patterns can occur with digital sensors.
- Optical Quality: Two internal ND layers create more internal reflections.
- Precision: It is harder to set the exact correct density.
In contrast, the fixed ND 0.6 offers optimal optical quality and consistent colors.
Relation to the 180-Degree Shutter Rule
The 180-degree shutter rule is the core of the cinematic look. At 25 frames per second, the shutter angle should be 180 degrees (1/50 second). The ND 0.6 is often the first filter cinematographers choose because it:
- Makes the Rule Achievable: In typical daylight, it's almost impossible to maintain 1/50 second with a wide aperture without an ND.
- Optimizes Motion Blur: The correct shutter speed creates natural, cinematic motion blur.
- Preserves Aperture Control: You don't have to stop down to f/8 or f/16.
Specifically: at f/2.0 with ISO 200 and ND 0.6, you can still achieve 1/50 second in bright sunlight – that's the goal.
Specifications
- Optical Density: 0.6
- Light Loss: 2 stops
- Multiplier: ND4
- Typical Transmission Rate: 25%
- Usage Range: Bright to very bright daylight
Practical Application Examples
- Outdoor Interviews: Sunny days with open apertures for background blur.
- Documentary Film: Consistent motion blur in various lighting situations.
- Music Videos: Cinematic look for outdoor shoots.
- Cinema Productions: Standard filter for daylight scenes.