“Infrared photographers have a much harder time finding glass that can provide this neutral darkening effect reliably for their creative medium when most of it made for visible light,” Kolari Vision tells PetaPixel. “That’s why we decided to make an ND filter that can do both.”
While there are filters marketed as “IRND filters” on the market,” they’re designed to block IR light for visible light photography rather than to serve as ND filters for IR photography.
“Historically the first ND filters were completely transparent in the IR spectrum,” Ilija Melentijevic of Kolari Vision says. “Since NDs were used for long exposures, eventually this IR transmission would leak through and contaminate the issues. It was so common, that people used to use ND filters instead of an IR pass filter like the R72 so they could shoot IR.
“As this became more of a problem, companies launched the ‘IRND’ — basically ND filters without any IR contamination. This is typically done by just putting an IR cut element into it, instead of making them neutral to the IR range also.”
The KOLARI IRND Filter is designed to be consistently dark and 100% color-neutral from 350nm all the way to 1000nm in the near-infrared spectrum.
“This glass is truly indifferent to whatever wavelength of light is passing through it, and because of these constraints, it actually delivers better results in more traditional visual art mediums,” Kolari says. “The glass is made to match the spectral sensitivity of a camera sensor, which includes near UV and IR, rather than just the visible light that an [Optical Low Pass Filter] OLPF filters for.
“We think pushing the industry in this direction will lead to more versatile optics that enable a wider range of creative choices without sacrificing image quality or the practicality that we’ve come to expect when shooting in the visible spectrum.”
Build-wise, the IRND Filter features Corning Gorilla Glass that provides strength without thickness. It also has a lower refractive index than Schott B270 for better sharpness.
Surrounding the glass is a thin 3.4mm brass ring that provides reduced vignetting and smoother installation than aluminum housings with less cross threading and jamming. Two-stage knurling on the edges provides grip when handling the filter with dry hands or gloves.
On the surface of the filter are premium coatings that reduce reflectivity while helping the filter to resist water, oil, and scratches.
Here are some sample photos captured with the Kolari IRND Filter by the Kolari Vision team (the IR photos were captured with the IRND stacked on the IRchrome filter, which recreates the look of Kodak Aerochrome):
Here are some long-exposure photos captured in visible light by photographer Greg Dubois:
The KOLARI IRND Filter is available now through the Kolari Vision online store in 67mm, 77mm, and 82mm sizes with up to 20 stops of light reduction. The 4-stop and 5-stop filters cost $130 for all three sizes. 10-stop costs $160, 15-stop costs $170, and 20-stop costs $200. All filters come with a lifetime warranty.