Science versus art; it’s the unique combination that allows cinematographers/shooters to be both creative and tech savvy. In other words, you have to know the tech to be able to make the art. Yes, I am sure there are a number of creatives who will dispute this notion but remember Picasso was a young realist drawing prodigy before breaking up realistic form into the art he is well known for today. Thankfully, we do not have to be full on scientists. Schneider-Kreuznach Optics has taken over the role of hard-core scientist for us with the development of their new RHOdium FSND (Full Spectrum Neutral Density) filters.
Filters and light can take a little bit of scientific experimentation to see what filters work best with a digital cinema sensor. We often ask ourselves which combination gives us the most natural pictures or not; it all depends on the look you are trying to achieve. Some believe one type of neutral density filter is best for a specific camera while that same filter might present a green cast when used with a different sensor. Thankfully, the Schneider RHOdium Full Spectrum Neutral Density filters block light without any color cast and should work equally well on any camera system.
I had one lovely weekend with Schneider-Kreuznach Optics new RHOdium FSND filters. It was enough time for me to play scientist, but not enough time to play artist. The first question I wanted to be answered was how did these filters work when used with the Blackmagic URSA Mini Pro which is a camera susceptible to IR pollution when using additional ND filters and not the filters on the camera’s ND Filter wheel. If you are using any of Blackmagic’s cameras that do not have an ND Filter wheel then IR pollution is a bigger problem. For example, the Blackmagic Cinema Camera and Pocket Cinema Camera need IR cut filters above 1.2ND. I prefer to carry one set of ND filters and I want the entire set to deliver perfect color accuracy. Below you can see I shot a color chart with every filter they sent me. The lens I used was a Canon 16-35mm L series.
As you can see above these filters did not create any kind of color cast in the deep blacks or black fabrics. The only post-production I did was add the filter tags and match exposure since the 3.0 ND was a little too much ND for the Blackmagic URSA Mini Pro and the Canon 16-35mm F2.8 lens I used for these tests. If I had a Sigma 18-35mm Cine Zoom and its T2 aperture the 3.0 ND might have allowed me to shoot wide-open on a bright summer day if I wanted.
Schneider RHOdium for Still Photography
But I also wanted to see how these filters looked on my Canon DSLR. When I shoot cityscapes I tend to shoot long exposures. What can I say? Nashville is located on the Cumberland River and the river can look kind of blah at a high shutter speed. As you can see below the filter helped me drag my shutter so the river can appear to be smooth and more reflective which is way better than the brown chop we usually get. In the past, if I stacked filters to achieve the same long-exposure I tended to get vignetting or some form of color cast from the filter combination. That color cast can be difficult to color correct out of the image leading me to shoot Black and White for a lot of my long-exposure cityscapes. Who wants to be pushed into a pigeon hole of creative choices because of a filter. Not me. With the RHOdium FSND 3.0 I was able to drop in one filter to achieve the same effect with zero color shift.
RHOdium Full Spectrum Neutral Density Filters
First off, the name of these filters come from the Greek letter rho or “ρ.” In Physics the same Greek letter represents the unit of Optical Density and Rhodium is a component of the “Platinum Group of Metals” on the periodic table. So, yes Schneider has introduced precious metal to it’s latest filter line.
These filters are built the color critical standards of 4K, 6K, and 8K cameras. These new sensors have gotten better at controlling IR pollution, but it is still a problem and no shooter wants to be surprised with red-tinged blacks. For color-accurate video, IR absorption needs to be necessary for a filter. This is especially true with higher density filters. Think 1.2 ND and up. According to Schneider, “RHOdium FSND filters are manufactured to finer flatness/parallelism specifications than ever before. These new filters help resolve even the finest detail. Schneider has engineered an extremely thin neutral density interlayer sandwiched between two sheets of crystal-clear Schott water-white glass. The thin interlayer results in excellent transmitted wavefront flatness/parallelism.”
In my opinion, these filters just worked well. For the little time I shot with these filters I saw zero color casting or tinting of my deep blacks in my video or still photography. Schneider allowed me to test all ten of the filters and I can say all ten proved the exact color accurate image as I expected. When delivering costly and expensive footage to a client the RHOdium FSND seems like a smart investment toward color perfect footage.