Digital camera technician Stephen Price explains what you need to know when you shoot with the Silicon Imaging SI 2K cameraThe film industry’s buzzword of the day is RAW. You hear it everywhere – often loosely thrown. The photographic industry has been using a similar system for many years and is at one with it. But with the restless advances of technology, the ability to capture one RAW frame has evolved into allowing the capture of 25 and even 1000 RAW frames in ever increasing amounts.

A film friendly analogy of RAW camera data would be ‘digital negative’. This is because of its ability to capture native digital data off the sensor without further destructive processing applied, such as a white balance.

RAW cameras include Thomson Viper, Arri D-21, Dalsa Evolution 4K (now unfortunately no more), Red One, Vision Research Phantom HD, Silicon Imaging SI-2K and the new Arri Alexa.

Unknown to many as it sits deeply in the wake of the Red ‘Revolution’, the SI-2K is made by P+S Technik, the same company that brought us the Pro 35 lens adapter.

The SI-2K uses a single 16:9 format 2/3in CMOS sensor with a maximum resolution of 2048×1152. Its super 16mm film-sized sensor design produces the same shallow depth characteristics of Super 16 and enables the use of lower cost 16mm film style lenses. Shooting flexibility is enhanced with its interchangeable mount system, supporting the use of B4 2/3in video lenses, high-quality 35mm cinema PL-mount lenses as well as F-mount and compact C-mount lenses. And yes it is RAW.

SHERLOCK HOLMES

I worked with the SI-2K on Guy Ritchie’s feature film Sherlock Holmes starring Robert Downey Jr and Jude Law. Ritchie is no stranger to the SI2K, his recent Nike ‘Evolution’ commercial saw the Mini adapted into a helmet rig to produce a mesmerizing point-of-view. The lightweight, compact design afforded us unique insight into a football player’s ascent up the ranks from grass roots to Premiere League with all his highs and lows along the way. The camera let us experience the journey through his eyes and we connected supremely with his pain and triumph.

Likewise, Sherlock Holmes called for many high action sequences for a lead character. The SI-2K camera was used in conjunction with a body rig to produce focused shots of Downey Jr as he ran though the streets of Victorian London. It was vital for the whole camera system to be light, versatile and above all reliable. At Take 2 Films, I spent several weeks designing a portable recording system which was mounted in a backpack. Then, with complete control of the camera I was able to record and transmit a wireless video signal from one lightweight portable unit.

Ritchie’s Sherlock Holmes is primarily a 35mm film production. For many action sequences both the SI-2K and the Phantom HD were used alongside contemporary 35mm cameras. One of his criteria for the RAW digital system was that the results had to inter-cut seamlessly with the rest of the picture. The Phantom HD’s Super 35mm sensor and 14-bit colour depth would present no problems when matched with 35mm film, but some people were sceptical about how the SI-2K’s 2/3 inch chip would hold up. When the footage arrived at the Digital Intermediate it was a surprise to all just how well the SI-2K footage looked when printed and cut with 35mm film.

SLUMDOG MILLIONAIRE

Another recent feature production to use the SI-2K is Danny Boyle’s Slumdog Millionaire which premiered at the October 2008 BFI London Film Festival. This vibrant, modern love story set and shot in India used the SI-2K Mini, often held in the palm of one hand with a tiny monitor held in the other hand. Wires went up the operator’s sleeve and into a backpack carrying a hard drive recorder. This permitted an incredibly inconspicuous shooting style whilst retaining cinema quality.

SI SET-UPS

The SI-2K camera systems can be used in its ‘production camera’ mode where the sensor is docked into the camera body. In this set-up the ergonomics are similar to a typical camera, with a viewfinder, on board monitor and video outputs for monitoring. The internal hard drives allow direct-to-disk recording and a touch screen interface places the key controls at the fingertips of the camera operator via ‘SiliconDVR’ camera software. Every image shot is captured in real time and stored into data files. The images can be played back instantly and individually deleted if necessary.

The SI-2k Mini configured in a helmet rig, along with a Preston Remote Focus System. On location for Guy Ritchie’s Sherlock HolmesThe SI-2K can also transform itself into a mini-camera by separating its sensor, which is roughly the size of a cigarette packet, from the camera body. With just one cable tethering the ‘eye’ to the recorder, the camera becomes very lightweight and compact, delivering a whole new dimension for the operator with no loss of image quality. The SI-2K Mini can also be wired via Ethernet directly into a laptop computer, eliminating the need for the camera body to act as a recording device.

When using a laptop the same interface software is used to control the camera, and the images can be recorded onto most hard drives. With these numerous configurations this camera really has all bases covered, no shot is too big or too small. As well as this, the camera can also shoot many different frame rates depending on the resolution. In a 1920×1080 resolution the maximum fps is 30p, but if you lower to 720p you can get 85fps. At standard definition you can shoot up to 150fps and that gives the user much more options over other cameras such as the Panasonic Varicam.

RAW FORMAT

Like many other RAW based cameras out there, the SI-2K shoots in its own RAW file format. Just like the Red One and the Phantom HD, these files need to be converted to another format before they can be used in post-production. This process is often referred to as the ‘Virtual Telecine’, because a RAW file holds similar large latitude and muted saturation characteristics to film. As with traditional ‘Best-Light’ Telecine-to-Tape, the render process of a RAW file involves a grading correction to extract the most information and to produce the best possible images for the following on-line stage.

When the preservation of quality is crucial, files are usually rendered to DPX or 16-bit Tiff. Otherwise, for speed or convenience, the converted RAW files can be delivered on any tape format, commonly HDCAM SR.

I believe any production team thinking about working with RAW based cameras must fully understand the whole process. Many users tend to fall at the first hurdle. In traditional video we are all familiar with a tape being delivered to post-production straight after filming. Some people expect this to continue with these hard drive based cameras and fail to understand that it cannot apply to RAW.

The rendering process is often overlooked and the time and cost factor in rendering is not always appreciated. Working in the RAW domain can deliver unsurpassed image quality and, as a way of working, it can be very rewarding.

As with any new technology there are pitfalls along the way, I am convinced the Achilles heel with a RAW camera is in this render process. If performed by an experienced professional it is more than probable that the result will be supreme quality images, but if not, it’s possible to encounter multitudes of problems. It’s is therefore very important to know that just because the camera records onto hard drives, it does not necessarily mean the result will be cheaper or quicker than non-hard drive mediums.

WORKING WITH FILES

Take 2 Films Services in London [www.take2films.co.uk] stock the Phantom HD and the Sony F35, and currently is the only rental house in the UK to own the complete SI-2K camera package. A partnership has been created between Take 2 and My Therapy data rendering and grading facility [www.mytherapy.tv]. By working with My Therapy, clients receive a service that guarantees the best possible images. In most cases, at the end of a day’s shooting a hard drive is delivered to My Therapy, the footage rendered overnight and the results delivered by the morning.

The most common codec used to record the camera data is the CineForm Raw codec. It records RAW 10-bit files, which are either wrapped in an AVI, or a MOV file. After downloading the free plug-in from CineForm (www.cineform.com) the client can watch the RAW files in either Windows Media Player or Quicktime Player. This allows the user to import their RAW files directly into almost any post-production package including Final Cut, Premier or After Effects, and cut an offline with minimal hassle.

When I’m on set, once I have copied the rushes from the camera’s hard drive to my Raid drives, I use Iridas software [www.iridas.com] to play back the RAW files. Due to the nature of transferring data from one hard drive to another, I prefer to use a third party application to validate the integrity of the files. With Iridas I can also create a grade for the rushes and with this grade I can upload to the camera as a look-up file. These look-up tables (LUTs) are basically a non-destructible grade applied in real time to cameras output.

The LUTs are a massive help to put people’s minds at ease. If unfamiliar with the look of a RAW image, the flat washed-out tones can be quite disconcerting. I am able to work with the DoP to quickly produce a grade and apply it to the monitors on set. This LUT can be toggled on and off with greatest of ease, and it can be saved and sent along with the rushes to the data rendering facility to aid the grading process.

The beauty of working with RAW files is that in post-production there is nothing that can’t be undone. If the shadows become a little too crushed or the colour temperature is a little too warm, these changes can be made with no detrimental effect on quality.

At the end of a shoot, I will have made multiple copies of the rushes. Typically, I make three copies to safeguard me from possibility of hard drive failures. I take away two copies and the third is delivered to the client as their master negative and, as a rule of thumb, the master should never be touched. A copy is made to work on, but the RAW rushes should always be saved to allow for any future changes that might be made.

The Mill in London [www.the-mill.com] has recently set up an in-house data rendering facility. As RAW data becomes increasingly widespread throughout the industry, the need for these specialist facilities becomes more necessary. Until recently there has been a reluctance within post-production facilities to take the plunge into RAW rendering and this, I believe, is partly due to cost and commitment. The shear storage space and render power needed to convert this data, especially for a long production such as a feature or TV drama, is immense.

Slumdog Millionaire – DoP Anthony Dod Mantle liked the SI-2K Mini so much he shot much more of the film on it than he had originally intended to. Ultimately 65 percent.Post production company The Moving Picture Company handled the post for Slumdog Millionaire and Martin Parsons, Head of Imaging, commented on the SI 2K data pipeline: “We developed our own workflow to extract just the frames plus handles from each of the shots which came in on over 50 drives.

“These RAW images were ‘digitally developed’ into log files for grading, paying particular attention to match the SI camera shots to the film neg scans to get an integrated finish as possible.

We also made sure that the transformed RAW images could be graded to match the reference .look LUT files supplied from set. We could then have that as a starting point for the grading session.

“There was a reasonable amount of MPC proprietary software written to get these results (fortunately we have a fair sized R&D team that services the film VFX side) as well as a lot of work done by our Digital Lab editors in prepping the shots for the grading sessions.”

MILL WORKFLOW

Recently I assisted The Mill in setting up a suitable workflow for the SI-2K. In my opinion, the Iridas software is the most powerful tool for grading and de-bayering any RAW data format. With their facilities and this powerful software, The Mill is now fully able to convert rushes for all RAW data cameras. In addition, to assist with the workflow familiarisation, I was commissioned to shoot a short film entirely with RAW data cameras.

The short film was shot over two days using the SI-2K and the Phantom HD, both supplied by Take 2 Film Services. The script required many Steadicam shots and using the SI-2K Mini for this was uncomplicated. I was able to attach a Wireless Lens Control to the system and remotely start and stop the recording. Although the camera still had to be tethered to the recording device, by keeping the camera small and light on the Steadicam rig, we could achieve shots in tight areas including doorways and stairways with great ease.

One shot required a static over-the-head viewpoint and with budget and time restrains this set up with another camera could have become complicated very quickly. With the SI-2K I detached the sensor from the camera body and used a standard C-Stand and Flag Arm to support the sensor and to manoeuvre it into position directly over the subject.

As we all witness the decline in the use of super 16mm film in the UK television industry, the way is open for new technology. In the past few months, in TV drama alone, I have witnessed the use of the Phantom HD, Red One, SI-2K, D-21, F35 and numerous other new cameras. Each of these camera systems brings their own production and post-production requirements. They way we work with these systems is continuously evolving; the gap between the work on set and post-production is narrowing. These are exciting times and the more we understand the potential of these systems and the quality of the images they produce, the more we can push the technical boundaries.

SHERLOCK HOLMES

Shooting With The Sherlock And Slumdog Camera