SAIT FILM VIDEO PRODUCTION
RESEARCH ASSIGNMENT
BODY MOUNTED CAMERA STAIBILISATION SYSTEMS
BY
07/04/06
BODY MOUNTED CAMERA STABILISATION SYSTEMS
Generically referred to as STEADICAM® (though the word itself is a registered trademark of Tiffen) by the lay person and moderate film geek, these body mounted camera stabilisation systems have been in use for around thirty years; ever since cameraperson and inventor Garrett Brown saw a need for a system to produce smooth gliding images that were free from the constraints of the more traditional mounting systems such as tripods, dollies and cranes.
To put the camera on the shoulder directly (to literally go handheld) would amplify and exaggerate the natural movement and impact of footsteps, breathing and heartbeats, therefore creating a very jerky and unstable image. Stylistically, of course, this can be the desired effect. With the invention of body mounted camera stabilisation systems the camera could move with the operator, to go with the operator practically anywhere. Where a dolly could not go due to its track being in shot, a steadicam could go. Up and down stairs, weaving in and out of obstacles all while tilting up and down and panning side to side, these body mounted camera stabilisation systems created a whole spectrum of choice both stylistically and logistically.
Invented by Garret Brown 30 years ago, his fundamental design has not changed since, although many individuals and companies have manufactured their own versions. In addition it would be prudent to point out now that there are no gyroscope devices in a body mounted camera stabilisation systems, contrary to common belief they use gravity, tensile and elastic energy. The original patent was bought by the company Cinema Products soon after its first use in a theatrically released film. Soon after this the device won an achievement award in technology from the Academy of Motion Picture Arts and Sciences.
Made up of three distinct parts, a) the vest, heavily padded on the inside with a hard metal shell on the outside linking the appropriate parts together, b) the camera support pole with battery and monitor otherwise known as a sled and c) an iso-elastic arm made of metal with a drum and cable or spring system which isolates the movement of the operator from the camera and vice versa.
The arm is key to the isolation required for a body mounted camera stabilisation system to work properly. It serves two primary functions, firstly to counteract gravity in that the arm is calibrated to produce an upward force directly proportional to the weight of the camera and sled.
The second is to isolate the movement of the operator such as impact vibrations of footsteps from sled and camera. This is achieved via the elbow in the middle of the arm that acts as a double jointed hinge and a similar hinge on the sled end of the arm, therefore any aberrant force is dissipated or indeed not transmitted at all to the sled.
The sled itself has functionality that keeps the camera and therefore the image stable. Firstly the point at which arm attaches to the sled has a gimbal mechanism which allows very smooth and free movement around the X, Y and Z -axis allowing the sled and the camera to stay pointing in the same direction while the operator adjust stance and direction. Movement along the Y--axis (side to side) and Z-axis (up and down) is done by manipulating the pole of the sled or the iso-elastic arm. This gimbal attaches at a point on the sled support pole approximately 10% above the centre of gravity proportional to the length of the support. This prevents any unwanted roll or pitch meaning the horizon is as fixed as possible. The point at which the camera attaches to the pole, more specifically, referred to as the sled has room for adjustment, this mechanism indeed also has adjustment for the way the camera sits on the X and Y-axis.
The side-to-side and front to back balance is a further safeguard to the preservation of a stable image and maintenance of a horizon.
Depending on the operator’s dominance of left or right handedness, the point at which the arm attaches to the vest can be adjusted to either the left or right. The point will more than likely be positioned on the hip of the operator, though newer designs incorporate different attachment points such as an arm extending from the back, centralizing the forces exerted on the operator toward his/her centre of gravity and not either left or right. The best or wealthiest operators will have a vest custom made using their own bio-metric measurements to get the best possible fit.
As a counter balance to the forces created by the camera a sled will often have a monitor and a compartment of batteries attached to power it. Having this counter balance in addition to an attachment point above the centre of gravity means that camera will not roll a full 360° if pushed off balance and will return to its horizon.
Once everything that is necessary to operate the camera is attached or inserted (i.e. batteries and tape stock) and batteries for the monitor are inserted; the adjustment and calibration of the X and Y-axis of the sled is necessary for balance (side to side and back and forth).
The operator will place the sled on an appropriate mount, usually a c-stand with a baby plug (plus a sandbag for safety, of course). Once mounted the operator will watch for rotation around the axis, manually adjusting the sled to inhibit as mush as possible any balance issues. From here the operator will adjust the tension around the Z-axis, allowing what is referred to as a fast or slow drop to the normal. An operator will adjust as necessary this tension depending on his experience and the desired product/effect.
Now the sled is calibrated, the camera is up and running and operational, the operator will put on the vest, adjusting as necessary for a comfortable fit and then attach the arm, the upward force of which is not counteracted until the sled is attached. Once the sled is calibrated it is returned to a standby bracket also on the c-stand.
The operator once wearing the vest and arm will literally place the end of the arm inside the gimbal handle and lift the entire apparatus off the standby bracket. Further adjustment is now necessary given that no two shoot days are the same, in that the iso-elastic arm must have its drum and cable tightened or loosened, or if it is a spring type of arm this must be adjusted accordingly.
An operator is aiming to minimize movement of the sled caused by the movement of his/her body; the operator will literally jiggle up and down on the spot to watch for up and down movement of the sled and camera. A hexagonal wrench or allan key is used to adjust the tension, until the jiggle barely registers on the sled. The operator is now good to go.
However, a few techniques and mechanisms remain to save the operator from injury and premature exhaustion. In newer designs of body mounted camera stabilisation systems a quick release system was implemented after the death of an operator. While operating on a boat out at sea the operator was thrown off balance and fell overboard with all the equipment, vest, arm and sled still attached, and drowned because he could not free himself from his apparatus.
After this a safety mechanism in the form of a quick release cable system on the vest was developed for emergency use only, such as the above scenario. An operator will pull the cable with force to release a series of latches that when undone will cause the vest, arm and sled to fall away freely from the operator, therefore saving his/her life.
One thing that all operators of body mounted camera stabilisation systems will state is that it is physical work, thusly they encourage and practice a stance during short respites to save themselves unnecessary exertion. The operator will lean back slightly and bend at the knees also slightly to bring the arm and sled in closer to the body. Instead of the centre of gravity being in front of the operator it is now closer to him therefore less force is exerted. Actually operating the system effectively is learnt through practice and trial and error. Because the arm is usually attached very near to the operators’ hips, it becomes essential that an operator develops good control of their core region; lifting and pushing or dropping and pulling of the hips is how, in conjunction with hand movement, an operator will create a smooth image while moving with the setup.
The idea of this technique is to move the arm and sled where you want it to go with your hips more than any other appendage and not the other way round. While physically operating the camera during a take or indeed a rehearsal the operator, no matter of how physically fit, has to counteract the effect gravity exerts on the setup. This done by leaning back away from where the force is pulling, moving the centre of gravity to a point usually near the operators’ hips.
It is not unknown for an operator to rehearse their movements a dozen times, as they have to be aware of so much more than just what the camera is capturing. They have to be mindful of their surroundings, the width of doorways, ceiling height, light placement and directions (showing them in frame and creating adverse shadows are reason enough). Nearly always an operator will have an assistant or a spotter, someone who during a rehearsal and indeed a take will follow and monitor the actions of the operator. During shots while going up or down stairs, for example, the spotter will guide through feel alone (usually due to sound being captured at the same time) the operator during difficult or dangerous movements.
Though body mounted camera stabilisation systems were primarily designed for maintaining smooth gliding images that in essence use the horizon as a point of reference, given their inherent capabilities they can also tilt up and down and pan side to side. The operator will of course use their hands for such occasions, using one hand on the gimbal handle and the other usually below the gimbal attachment point. The hand will never firmly grip the sled support pole as doing so would negate the iso-elastic effect of the arm. Instead the operator will using a technique of minute adjustment with the fingers, one could refer to it as fluttering, rapidly and lightly adjusting the direction and movement; an additional mechanism for maintaining a smooth shot.
When tilting up, however, the operator must control such a movement without breaking the fluidity of the shot. They will use the their hand to push the sled below the gimbal forward; therefore tilting the camera up. Often using just the thumb and little finger (similar to a hand gesture representing a phone) and perhaps a knuckle or two, this movement is aided by the tension of the gimbal, while during prep and calibration the operator will test the timing of a 30° fall to see if it fast or slow.
To tilt down however the opposite must occur, again the operator will never grasp the sled support pole tightly but to bring to the camera to tilt down their free hand will slowly bring the bottom of the sled toward themselves.
However this is assuming the lens and operator are facing the same direction for such a movement. Often an operator will have to face the opposite direction to which the camera is pointing, the maneuverability and reach of the iso-elastic arm allows this to happen. If for example the subjects of the scene were walking toward camera down a city street with numerous extras, it would be prudent for the camera to stay in positions correctly. However the operator may opt to face the same way as the subject so as to move and weave between the oncoming human traffic. Indeed an operator may elect to have a spotter do the guiding, this is the preference of the operator not a standard rule or guide. The onboard monitor itself is particularly useful in such situations; the operator will move their eyes rapidly from monitor and to movement ahead (I would liken this to watching TV while driving and keeping the car behind dead centre in one’s rear view mirror).
Also the operator will have to, on occasion, perform a technique in the middle of the shot whereby the camera doesn’t shift at all but the operator has to reverse the direction he or she faces but continues moving in the same direction.
As with anything all this takes practice and knowledge, from just putting on the vest properly to calibrating the sled and practicing the techniques for getting a great shot. All of it is incredibly physical work and thusly only a few people are exceptionally good at it. But at the end of the day it is what you do with the technology more than the technology itself that makes it such a brilliant tool for filmmaking. The arm and sled can also be attached to the front and back of vehicles to follow subjects that are moving at too high a speed for an operator to follow on foot. Though a great tool of filmmaking it is not without its limitations. Again it is tiring for the operator, it must carry all its own cables and accessories, and must be used with long focal lengths of prime lenses or zooms at telephoto, as movement inherent in the cameras mechanisms will create a jitter in the image.
NOTABLE APPLICATIONS.
The first most notable use of a body mounted camera stabilisation system is in 1976 for the boxing film ROCKY (John G. Avildsen, 1976), operated also by the inventor Garret Brown. Used to great applauses the technique is used during the training sequence following Rocky Balboa though the streets of Philadelphia ending with a musical crescendo following Rocky closely up the steps of the Philadelphia museum of modern art. This was the first time such a system had been used, and having the camera literally follow the subject through doors, around corners and up stairs from close ups and wide shot was a miracle of engineering and added a layer of mysticism to the magic of cinema.
In Halloween (John Carpenter, 1978) the Panavision Panaglide system was used to great effect to simulate the subjective viewpoint of an actual character most notably in the beginning sequence (this stylistic technique has been used a thousand times over, since).
For The Shining (Stanley Kubrick, 1980) a steadicam arm and sled was attached to the front or rear of a golf cart to follow the young Danny as he rides his pedal trike through the creepy hallways of the Overlook Hotel.
Stylistically applying the change of ambient sound as Danny rides from carpet to hardwood floor as we follow him, this particular application and example adds a menacing tension. Also this use of a body mounted stabilisation system promotes the isolation of the situation by a) not showing any one else but Danny until the appearance of the ghostly twin girls and b) using an uber wide lens that Danny and his trike practically engulf. Both these aspects discomfort the viewer, created in no mean feat by the use of, in this case, a mobile mounted camera stabilisation system.
An unexpected use of a body mounted camera stabilisation system came in the form of James Cameron’s Aliens (1986). Two hard as nails Colonial Marines carry heavy support weapons mounted to the arm of futuristic looking body mounted heavy weapon stabilisation systems. Though they both die in a horrible attack by the titular aliens; it is still really cool to see it.
Of course this leads into the use of body mounted camera stabilisation systems as the only method by which a feature films visual portion is originated. Alexandr Sukurov’s Russian Ark (2002) is at present the only such example.
Shot on an early version of high definition in 2001, the film takes place in the St. Petersburg’s Hermitage museum. In the first minute of the movie we take on the viewpoint of a twentieth century filmmaker (i.e. the operator) followed by a nineteenth century diplomat. They each experience the last 300 years of Russian history by entering, meandering and moving through the different rooms of the Hermitage museum. What is viewed is of course not exactly as shot, Sokurov augments a few shots in post with skewed perspectives and colour corrections. The fact that the marketing behind the film states that it was recorded in one continuous shot is, however, not so much a lie as it is a non-truth, semantics perhaps. The film itself had four false starts, but what in fact happened was the first half of one take (50 minutes) was cut in with the second half of another take. Hiding the cut surreptitiously in a pan past a column, the filmmakers were able to create the illusion of a single continuous take.
posted by Sheff @ 9:43 PM
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