Underwater adventures in 3D with the EOS C300 and Seacam
© Roberto Rinaldi
Filmmaker Roberto Rinaldi worked with Seacam's Harald Hordosch to create the first underwater housing for shooting 3D with a pair of Canon EOS C300 Digital Cinema Cameras. CPN writer James Morris discovers the amazing depths of the EOS C300's capabilities...
Shooting 3D is difficult enough, but trying to do it underwater adds yet another dimension of difficulty. Nevertheless, Roberto Rinaldi wanted to bring a more naturalistic, documentary approach to shooting 3D underwater. He wanted stereography to boldly go where this form of filmmaking hadn't gone before, capturing scenes in 3D that had previously only been experienced on regular video, or maybe not at all.
“This project started some years ago,” explains Rinaldi. “The idea of bringing 3D technology underwater was not something new, for sure. But at that time, a 3D production was a huge issue. Cameras were gigantic, so you couldn't use them in every situation. You would need a very big boat, a crane, numerous crew, and this brought the idea of 3D far away from the natural history documentary as we generally think of it.”
At the time Rinaldi began his project, large investments of money and time were spent producing big productions aimed primarily at IMAX cinemas. Despite the investment, from a technical point of view the stereography was far from perfect and a lot of sequences were difficult or impossible to shoot. A number of cheap 3D video systems were coming out that were easy-to-use but these produced very bad results, especially in terms of 3D technique.
“When filming 3D, two cameras are used to record almost the same image at the same time,” explains Rinaldi. “We have to reproduce the way humans see: our two eyes have a slightly different image. The difference between the two gives us the information needed to have the perception of the third dimension. A man with only one eye does not see in 3D and does not have a good way to evaluate the distances. But reproducing human 3D vision with cameras is really complicated. Basically, the greater the distance between two camera optics – known as the interaxial distance – the greater the 3D effect. The problem here is that if the 3D effect is too strong, watching the images can be very painful for the eyes and absolutely not enjoyable. The appropriate interaxial distance also depends on how far the camera is from the subject matter.”
However, underwater it's always best to shoot as close as possible to the subject. This is because on land, on a foggy day with just 50 metres of visibility, it would cause difficulties. But for a diver, a visibility of 50 metres underwater would be a dream come true. For this reason, an underwater cinematographer will shoot as close as one metre or less from the subject. “At this proximity, the interaxial distance must be extremely small,” Rinaldi continues. “This means that it will be almost impossible to use a side-by-side system. Instead, we must use a beam splitter. This is a system based on two cameras at 90 degrees with a special mirror at 45 degrees in between. While one camera is recording the image through the mirror, the other one is recording the reflected one. Using this system, every interaxial distance is possible. It is also possible to completely overlap the two images, one on top of the other, or to scale them by a few centimetres.”
With all this in mind, Roberto Rinaldi had the challenge of building a housing with some very special characteristics. Firstly, the housing had to contain two cameras as well as the matte box with the mirror, which meant the cameras would have to be quite small. Secondly, he wanted his stereography to be perfect. This would necessitate easy access to changing settings, in particular the interaxial distance, because a preset system would only be optimised for a specific distance. Rinaldi also wanted to be able to access all the settings of both cameras, which was likely to be problematic through a thick aluminium housing. There was no existing system for this, so one had to be invented.
Rinaldi also wanted to be able to control the stereography, which required special monitors with 3D Assist functionality. These are able to show the two images from the two cameras overlapped. This makes it possible for the stereographer to evaluate the separations between the two images, and make a judgement on how the resulting 3D image will look, based on experience.
“One of the main problems of the existing rigs was related to the lens port,” explains Rinaldi. “Underwater, the angle of any lens is reduced by the refraction caused when the light goes from air to water. To avoid this problem, on normal 2D cameras spherical dome ports are used, but the use of a dome port on 3D cameras was considered impossible, for a number of very serious reasons. On the other hand, a flat port causes the loss of angle of any lens. A flat port is also not very resistant to pressure, due to the large exposed surface. Having a flat port able to resist to a pressure like the one you may have at 50, 60, or more, metres underwater means you have to use a very thick glass – or Plexiglass – which will affect optical quality.”
Rinaldi discussed these issues for months with Harald Hordosch, founder of underwater housing specialists Seacam. “Harald was the only one that in my opinion could face these challenges,” argues Rinaldi. This was where the Canon EOS C300 entered the picture. “Both Harald and myself were attracted to the Cinema EOS C300 when it hit the market. My interest was coming from my incredibly successful use of an EOS 5D Mark II inside a Seacam housing, which was, in itself, a true revolution.”
After having experienced the quality of Canon camcorders in the past, and having learnt of earlier Canon models being used by many stereographers because of their reputation for perfect genlock and time-code synchronisation, Rinaldi's interest in the C300 was also raised by the size. “Finally we could have a camera which would allow us to use a reasonably small underwater rig!” he enthuses. “Also, the format of the camera would be perfect for putting in a housing and remotely controlling with a mechanical system.”
So Rinaldi and Hordosch began to develop a housing for the C300. But they didn't just want to produce a box for two cameras. They wanted to create an entire stereographic system for underwater use, and this is what they ended up achieving. “Studying the cameras, entering sizes and pictures in computer programmes, Harald and his father were able to produce a special dome port,” explains Rinaldi. “This is the first dome port for a stereo system, and it's unique. Thanks to its custom design, the Seacam C300 system is the only one able to keep the angle of every lens underwater. This housing is tested to 150 metres. We already did quite a few hours of 3D filming deeper than 100 metres.”
The housing is being used with modified Canon EF lenses, from a 14mm to a 50mm Macro. The interaxial can be set by the cameraman and the stereography controlled using the monitor with 3D Assist functionality. All of the camera's controls can be accessed underwater, and every feature used through the housing. These are all operated mechanically, with record, iris, and white balance controlled on both cameras at the same time. Despite containing two cameras in a stereographic configuration, the housing is no bigger than one for a traditional Betacam.
C300: the perfect choice for underwater
Having used the C300 for several months, Rinaldi lists the main points that he believes make this camera the best possible choice on the market for underwater 3D use. “The small size of the camera body,” he begins. “The sync and genlock are totally perfect, too. I know that many other cameras have a lot of problems on this side. This is a huge issue for 3D filming.” Rinaldi also cites the low operating temperature of the C300, since overheating could be a major issue when a camera is inside a housing.
The huge range of lenses is another major plus. “Canon EF lenses are extremely good in terms of quality,” Rinaldi continues. “The price is reasonably low and the size much smaller compared to cinema lenses.” The layout and positioning of the C300's controls also pays dividends while using the cameras inside the housing. “The function command is extremely clever,” adds Rinaldi. “It allows me to pass very quickly from ISO setting, to shutter speed, to white balance. This makes everything easier, since you only have very limited time underwater.”
The fact that exposure and colours are similar across the two cameras is another pleasant surprise. “This is extremely rare and extremely important in 3D use,” enthuses Rinaldi. “As you can guess, the two eyes must be identical in terms of colour and exposure. A disparity between the two cameras will cost a lot of money in colour grading.” The C300's low light performance impresses Rinaldi greatly, too. “It's incredible!” he exclaims. “And similarly incredible is the quality when you push the ISO up to 2,000 or more. This is extremely important in the dark underwater world and even more when you shoot 3D. In 3D you want to have a very big depth-of-field. In 2D, low depth-of-field is used to put emphasis on the subject and to isolate it from the rest of the frame. But when shooting in 3D this is achieved using the volumes in the image.”
The huge dynamic range of Canon Log proved highly beneficial, too. “Underwater there is a large gradient of light intensity from the upper part of the frame to the lower part,” argues Rinaldi. Canon Log allows detail to be captured right across the frame. Rinaldi also tested the embedded profiles. “I found Cine 1 really not good for the underwater use,” he adds. “Too much contrast meant the highlights were out of range. But the EOS profile was just perfect. Vibrant and saturated colours are ideal for the underwater realm. Using this profile is a great choice when working for a medium-budget production, as this will allow you to save a lot of money that otherwise you would have had to spend on colour grading.”
Overall, Rinaldi is delighted with the system that Seacam has created to shoot underwater in 3D. “Thanks to the Seacam C300 housing I was able to film in the Mediterranean for hours, between 50 and 120 metres in depth,” he enthuses. “I was able to go into the jungle and jump inside a cenote [a natural pit] in Cuba to film crocodiles. I have also managed to film crocodiles in shallow and murky waters inside a mangrove forest. I could film the waves breaking against the reef, the super-fast dolphins in Curacao, and shipwrecks in the Mediterranean. The matte box is so well designed that I don't have any fear of reflections, even when working with a back-light in tropical waters. I am able to work as I have with a regular 2D camera, with no limitations at all. In fact, the only limit is my imagination.”
Biography: Roberto Rinaldi
© Roberto Rinaldi
Roberto Rinaldi has been shooting underwater for over 20 years. He has a particular fondness for the Mediterranean, but has made sub-aquatic films all over the world. He was official photographer on Jacques Cousteau's boat, Calypso, with his pictures appearing in National Geographic and has dived in a lake in Tibet at 5,000m, as well as the Siberian Baikal Lake in -50C winter temperatures. He has performed as cameraman and cinematographer on the Secrets of the Dead and Oceans TV series for PBS and BBC/Discovery Channel respectively, as well as Wild Kingdom on Animal Planet.