Many creative choices are difficult, but your choice of neutral density filters shouldn't be. ARRI Full-Spectrum Neutral Density (FSND) filters offer superior image control with maximum flexibility and no optical compromise.

UHD and HDR are the future of filmmaking. With increased image quality comes the need for superior optical quality. Low-cost filters introduce artifacts such as flare, glare, reduced color saturation, and optical distortions, all of which compromise the integrity of high dynamic range and wide color gamut images. 

Many manufacturers sandwich the filtration material between two pieces of glass, which can introduce astigmatism and other optical distortions. ARRI FSND filters are surfaced coated, with highly-polished high optical quality glass as a base. They are distortion free, even when used in conjunction with long focal length lenses.

ARRI FSND filters leave image control to the cinematographer. They are perfectly color neutral, exceptionally resistant to flare and glare, protective of the color within the scene, and introduce no discernible image distortions at even the longest focal lengths. Most importantly, they eliminate far red ("IR") contamination without affecting skin tone.

Internal camera filters from ALEXA Mini & AMIRA also available for Matte Boxes

Features

Faithful to your image

• Color neutral and consistent from batch to batch
  Perfectly preserves skin tone and doesn’t fade over time
  No distortion and astigmatism when used with very long lenses (crucial for UHD)
• Eliminates IR pollution on any camera
• Exceptionally accurate and consistent exposure control
• Advanced anti-reflective coating reduces or eliminates interactions between lens elements and adjacent filters (crucial for HDR)

Effortless handling and simple tracking

• Made of extremely high-quality Schott B270i glass, with completely flat and parallel surfaces
• Oil and water resistant surface coatings protect against adverse shooting conditions
• Easy and fast to clean
• Laser-engraved barcodes facilitate quick check-in and check-out for rental houses

Future-proof durability

• C-Shaped, blackened filter edges resist chipping and reflection
• Hard coated for long filter life
• Long-lasting CORDURA® pouches lined with MICRODEAR® antistatic cleaning cloth

Neutral density filters are used more often than any other type of filter. Their effect should be limited to one attribute: reducing the amount of light reaching the sensor, with no other visible effect. This is not an easy task, and ARRI has created a line of filters that not only meets this goal, but exceeds it in ways not matched by other manufacturers.

Film is insensitive to red at the edge of the visible spectrum. Film NDs are transparent to this frequency range of light. Digital sensors require a small amount of this “far red” light to render skin tone as healthy and vibrant, but traditional film NDs are not spectrally balanced for digital requirements: they cut most visible light, but pass too much far red. This causes color distortions that cannot be corrected in post.

Early filter attempts by other manufacturers resulted in overcompensation, rendering skin tones as dull and pasty. These filters worked on some cameras, but not all. ARRI FSND filters preserve color balance perfectly, eliminating color distortions and preserving lush skin tones. They are universal filters that produce the same high-quality result with every camera.

Many manufacturers sandwich the filter material between two pieces of glass, which introduces optical distortions, especially with long focal length lenses. Each ARRI FSND filter is manufactured out of a single, highly-polished piece of optical quality glass that is surface coated and then sealed behind an optically-clear scratch, oil, and water-resistant coating. They are distortion and worry free, even at the longest focal length.

Design of ARRI Filters

Optical coating design presents big challenges, and, unsurprisingly, only a few optics manufacturers master the ultrathin metal film coating process to deliver high quality and highly repeatable performing filters. The complete multilayer thin-film coating on one clear glass substrate side is roughly a ten thousandth of the substrate’s thickness, comprising several layers or complex mixtures of dielectrics, semiconductors and metals. 

The absorbing layers embedded inside the coating stack have a thickness of only a few nanometers and thickness must be controlled with a precision in the range of 0.3nm or 0.000 000 000 3 meters. To give an idea of the scale we’re talking about, grass grows about 20 to 40 nanometers per second in the summer months.

Anti-Reflective Coating

For ease of access and replacement, MPTV filters are positioned in a matte box in front of a lens. While this position is convenient, it is optically delicate, and can result in flare-like ghost reflections being focused onto the imaging sensor. The severity of visibility of this stray light is proportional to spectral radiance, which usually increases with focal length. But it is also highly dependent on the specific optical design of the deployed lens, and the associated stray light paths.

Whether this stray light is regarded as problematic, or artistically valuable, lies in the eye of the beholder, and their specific imaging requirements. To facilitate a choice to the DP, and to avoid distraction from the objective lens’ flare, ARRI FSND filters are equipped with low reflective coatings on the smooth optical surfaces, and blackening of the edge surfaces.

Durability

Matte box filters are used in harsh environments and need to fulfil the camera team’s expectations on handling robustness, reliability, and optical performance over an extended period.

In the pictures you can see scratch marks, for which the load on a diamond tip with 200µm radius was progressively increased up to 50N (proportional to approx. 5kg load), while sliding on the specimen’s surface from left to right. 

The top image shows an ARRI FSND sample; the lower a reference competitor’s thin film ND filter, for which even the substrate shows spallation under the applied pressure.