As I mentioned in my previous article we recently had a great opportunity to shoot a fun project that required high-speed video recording of animals in motion in a controlled studio environment.
The Sony PXW FS7 4K camera is capable of recording frame rates up to 240 fps. With regard to affordable ultra slow motion video this is quite a technical feat, but not quite in the same league as the Phantom Flex 4K, which is capable of speeds from 23.98 to over 1,000 fps at 4K and up to 2,000 fps at 2K.
As we were preparing our shoot we had two very important technical questions to answer: “How much light will we need, and what type of light should we use?” This article intends to answer both.
1. How much light will we need?
We knew that to shoot slow motion video we needed a lot of light. But how much? Short answer: a lot more than what you would expect. For this shoot we filmed the majority of the scenes at 180 frames per second and cranked it up to 240 frames per second for some key moments.
The general rule of thumb is that your shutter speed should be set to a 180-degree angle or roughly double that of your frames rate so we needed to provide enough light to operate the camera at 1/350th of a second (for 180 fps) and 1/500th of a second (for 240 fps). Obviously, each time we double the frame rate our exposure time halves. So, for this shoot we would need four or five times more light than a standard 30 fps shoot.
So far, so good, but the real challenge was that the subjects for this shoot were dogs and cats. Although some of the dogs were well trained, often the best moments were totally spontaneous and not necessarily in the center of the set, or even within our frame. We needed to evenly illuminate a large area to account for the animals’ unpredictable movement and also provide enough light to shoot with a much greater depth of field than normal. To ensure that we didn’t miss any key moments we wanted to film at f/11 or even f/16. Easier said than done, of course.
Another interesting catch is that to get the optimal image quality from the FS7 we really wanted to maintain the camera’s native ISO. This was not a pure aesthetic decision, but also a technical requirement to shoot in Cine El mode. This “small” detail would prevent us from cranking up the ISO if we didn’t have enough light.
2. What type of light should we use?
We also needed to select the right equipment that could generate enough light for our high shutter speed and depth of fields, but that wouldn’t roast the animals with extremely high heat. Another very important aspect to consider when selecting lighting equipment for high-speed recording is flicker. Although we would not be filming at ultra high frame rates (1,000 fps and up) where this becomes even more of an issue, we wanted to be sure our lights were flicker free. The most reliable sources that diminish the flickering effect are large tungsten lights, HMI’s with electronic ballasts, and certain LED panels.
Bigger fixtures that provide more light usually require more power, so scouting your location [add link to article 035 “Location scouting and technology” here] is essential to determine what kind of output it can handle. For our shoot we needed a location that had a lot of surrounding outdoor space so our “talent” could blow off excess energy by running around, fetching balls, etc. After a long search we finally settled on a freestanding garage in a residential area. This was not a commercial space (we couldn’t find one with surrounding outdoor space) or a large-scale studio (too expensive for this project) so we needed to be extra conscious about not blowing a circuit. Powerful tungsten lights require a lot more power than an HMI or LED so we quickly eliminated them as an option.
After taking everything into consideration we opted to rent two Joker 1600 Bug Kits as our principle light sources. These are very powerful daylight HMI’s that can run on a 15 amp / 120 volt circuit, are dimmable, and have a frequency option for extreme high speed shooting. At 1600W, the Joker 1600 is comparable to over 6000W of quartz fixture output and produces twice as much, or one full stop more light, as the very reliable Joker 800 we have used in the past.
We put them in medium Chimera Quartz softboxes with 1/4 diffusion to soften the light and spread it evenly across the white seamless.
The aesthetic concept for this project required that the animals and props appear cleanly isolated on white with little shadowing or contrast, imagine any Apple commercial, but with cats and dogs. To accomplish this we also set up two LitePanel Astras [add ARC link http://www.adoramarentals.com/p-~lpastragbat/litepanels-astra-bi-color-w-battv-mnt] as backlights to fill in the shadows cast upon the seamless. The Astras packed quite a punch for an LED panel!
Here are some of the lessons we learned. The lighting package we selected worked well for this project, but we needed a bit more light so we ended up covering the ceilings with white seamless to maximize our output and bounce all of the available light on to the set. Not a big deal but a time consuming step.
Although the LitePanels are not nearly powerful enough to function as the primary source for a slow motion shoot they worked perfectly filling in the shadows. As they don’t generate any noticeable heat, we were able to adjust them on the fly to accommodate the different scenarios and different animal sizes. They provided a lot of flexibility and very needed additional light.
The HMI’s on the other hand produced a lot of heat that warmed up the overall set. The weekend was unseasonably cold, which worked to our advantage, but this is an important consideration when working indoors. The heat also worked surprisingly well for our purposes as it tired the animals out and made them a bit slower and more cooperative. If we were filming an actress for a makeup or food commercial this setup wouldn’t be a good match. Thankfully, everything worked well for us and we learned a ton.
In an upcoming article I’ll go over our experience using the Sony FS7 in the studio, the benefits (and challenges) of shooting in S-Log, and some interesting notes on high-speed post-production Workflows. Stay tuned!
Eduardo Angel is an independent Technology Consultant, Educator, and Emmy Award winning Visual Storyteller based in Brooklyn, NY. He currently teaches at The School of Visual Arts and the International Center of Photography, and mentors the photography program at the Savannah College of Art and Design.
Eduardo is a co-founder of the idea production company The Digital Distillery, author of popular filmmaking courses on Lynda.com, and regularly shares his thoughts on technology, photography, and cinema on his website eduardoangel.com