Neutral density (ND) filters are the most in-demand and essential photographic filters for several reasons. For photographers, an ND filter means precise control over the amount of light passing through the lens for greater creative control over exposure. For video content creators, ND filters greatly help in adjusting 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, or even ND100000, ND filters can generally be categorized into 3 basic groups:
Low-density filters (ND2 – ND8)
Medium-density filters (ND16 – ND200)
High-density filters (ND500 – ND1000/ND100000)
Low-density filters will reduce the shutter speed on a sunny day to allow you to reduce depth of field in very bright light or to use a wider aperture to stay under the diffraction limit. For example, these filters are necessary for shooting with your fast lenses like F1.4 or F1.2 at wide-open aperture for softer and more beautiful bokeh.

Medium-density filters will help you add motion blur to the subject in conditions that would not normally allow the camera's shutter speed to do so.

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

Solution to the color shift problem
HOYA offers its own exclusive and extensive range of ND filters, marketed under the PROND EX series, for photographers and filmmakers. PROND EX filters adopt HOYA's clear optical glass, mounted in a lightweight, precisely machined aluminum frame. The frame has front threads allowing for the attachment of additional filters or a lens cap.

Thanks to ACCU-ND technology, which places HOYA ND filters well above other brands, the image does not suffer from any negative color shift effects that can occur due to low-quality materials, poor manufacturing quality control, or issues with infrared band leakage in the light spectrum. This latter issue is the most significant one nowadays in photography and videography.

HOYA's exclusive ACCU-ND technology allows for equal light reduction across both the visible and IR spectra. Consequently, the photographer does not have 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 S-Log mode, the ISO cannot be set below 800. To achieve natural motion, it is recommended to adjust the shutter speed to the frame rate setting. During the day, the PROND EX 8, PROND EX 64, PROND EX 1000, or their combination (such as PROND EX 8 + PROND EX 64) would be necessary to achieve cinematic quality.

PROND filter combinations
The choice of ND filters depends on the photographer's intentions for achieving the desired effect in the image. If the effect obtained with a single ND filter does not satisfy the photographer's vision, combining PROND EX filters can also be useful. For example, the combination of PROND EX 8 + PROND EX 64 will produce an effect equivalent to an ND500 filter, which can be used to express a surreal, fantastic world. The combination of PROND EX 8 + PROND EX 1000 will produce an effect equivalent to an ND8000, which will allow for capturing the surface of the Sun without overexposure, with solid color and visibility of black spots.