Filter company NiSi have come up with a clever solution for those people wanting to use the Sigma 20mm F1.4 ART lens for video on full-frame cameras such as the Sony a7S/a7SII/a7R/a7RII or Canon 5D mkIII. The problem with the Sigma 20mm f1.4 lens is that it has a non-removable petal hood, similar to both the Nikon 14-24mm f2.8 and Canon 11-24mm f4. This makes makes it impossible to use a screw in filter, such as a variable ND.
The way around not using a filter would be to try using a conventional matte box, but you would have to mount it on rails and use a rubber donut. The trouble is, a lot of matte boxes would still vignette when using the 20mm lens on a full frame camera.
NiSi have made a custom filter holder that has been designed specifically to work with the Sigma 20mm f1.4 lens. The filter holder attaches directly onto the petal hood of the lens and allows you mount up to three 150mmx150mm or 150mmx100mm Filters. The thickness of these filters can only be 2mm and not the normal 4mm. Thankfully NiSi have a range of filters available that will work with this holder.
The filter holder is also compatible with Lee, Cokin, Hitech, and Singh-ray 360 Degree rotating filters. It’s made from aviation-grade aluminum with single element processed by CNC Machine. It also uses a matte black frosted finish on the surface. All of the screw-in accessories are made of copper and feature black nickel plating to help stop stray light affecting the image.
The Sigma 20mm f1.4 and a Sony a7 series camera provide arguably the best fast, full frame super wide lens combination on the market. It is good to see a company make a specialised product that allows this great combination to be used more easily when shooting video. You can purchase the filter holder for $170 US on Amazon.