Neutral density (ND) filters are the most demanded and essential type of photographic filters for several reasons. For photographers, an ND filter means precise control over the amount of light passing through the lens, allowing for greater creative control over exposure. For video content creators, ND filters are highly useful for setting shutter speeds to match the frame rate while maintaining the depth of field of the footage.

Among the varieties of ND filters, from ND2 to ND1000 and even ND100000, we can generally categorize them into 3 basic groups:
Light density filters (ND2 – ND8)
Middle density filters (ND16 – ND200)
Deep density filters (ND500 – ND1000 / ND100000)
Light density filters will lower the shutter speed on a bright, sunny day, allowing you to reduce the depth of field in very bright light or use a wider aperture to stay below the diffraction limit. For example, these filters are necessary when shooting with fast lenses like F1.4 or F1.2 with the aperture wide open for softer, more beautiful bokeh.

Middle density filters will help you add motion blur to objects in conditions that would generally not allow the camera shutter speed to do so.

If you are looking for more creative shots based on extremely slow shutter speeds, deep density filters are recommended. ND filters like ND500 or ND1000 will help you capture a dramatic, surreal fantasy world that cannot be seen by the human eye.

Color shift issue solution
HOYA offers its own exclusive and wide lineup of ND filters, branded as the PROND EX series, for both photographers and filmmakers. PROND EX filters use HOYA's clear optical glass mounted in a lightweight, precisely crafted aluminum frame. The frame features front filter threads, allowing you to attach additional filters or a lens cap.

Thanks to ACCU-ND technology, which puts HOYA ND filters far ahead of other brands, the image is not negatively affected by color shifts that can occur due to low-quality materials, poor manufacturing quality control, or issues with infrared light spectrum leakage. The latter problem is the most significant in photography and videography today.

HOYA's exclusive ACCU-ND technology achieves an equal reduction of light in both the visible and IR spectrums. As a result, photographers do not need to worry about color shift issues when using HOYA ND filters in different shooting conditions.

PROND filters in video production
ND filters are also an irreplaceable tool in video shooting. For example, when shooting with a Sony camera in Slog mode, the ISO cannot be set below 800. To obtain natural motion, it is recommended that the shutter speed be adjusted to the frame rate setting. During the daytime, a PROND EX 8, PROND EX 64, PROND EX 1000, or a combination (such as PROND EX 8 + PROND EX 64) would be necessary to achieve cinematic quality.

Combinations of PROND filters
The choice of ND filters depends on the photographer's intention to achieve the desired effect in the image. In case the effect produced by using a single ND filter does not satisfy the photographer's vision, combinations of PROND EX filters can also be useful. For example, the combination of PROND EX 8 + PROND EX 64 will provide an effect equal to an ND500 filter, which can be used to express a surreal fantasy world. The combination of PROND EX 8 + PROND EX 1000 will provide an effect equal to an ND8000, which will allow you to capture the surface of the Sun without overexposure, with solid color and visibility of sunspots.