Home built Steadicam
October 28, 2007
Steadicam is a kind of the stabilizer to reduce shake of the video camera. It is used for taking a video with walking or running. When take a video with running and the camera is on your hand or shoulder, the video will be taken with unpardonable shake. Ofcourse such the large shake cannot be canceled by built-in shake reducer. However the steadicam represents smooth camera motion in the video just like the camera is gliding in the air.
The Steadicam is a registered trademark of Tiffen Company LLC. However it has become a general name of this kind of camera stabilizer. (and so in this document) The steadicam has been sold from number of professional video equipment manufactures. The steadicam can be classified into two part of camera weight. The typical steadicam is held with a spring arm attached to the arm vest and fixed to the operator's body, and other hand there are inexpensive models that held it with a hand for light camcorders. The list prices for small handy-type steadicam is at range of ¥50,000 - ¥20,0000, and for typical steadicam with arm vest is at range of ¥500,000 - ¥5,000,000, so far as I know.
Principle of Steaicam
The steadicam utilizes only a simple dynamic characteristics of balanced object and it does not have any active control mechanism. Right image shows the basic structure of typical steadicams. It is divided into two parts, one is the balanced mechanism (black shadow) and other is the support mechanism (gray shadow). The balanced part consists of camera, counter weight and vertical post joining them. The balanced part is attached to the support mechanism at center of mass with a 3-axis gimbal.
Thus the variations of angular direction of the supprt mechanism is canceled by the gimbal, and also any vector of force acts the center of mass does not generate a torque. Therefore any rotations of pitch (X-axis), yaw (Y-axis) and roll (Z-axis) that resutls shake of video is not occured and the camera holds a steady direction.
In most case, body mounted steadicam is used. The weight of balanced part is supported with a spring arm and shakes due to walking is also reduced by the spring arm. For light camcorders upto 1 kg, hand held steadicam can also be used. The counter weights are attached to two positions, front and back, to increase moment of inertia of yaw.
Building a Steadicam
There are inexpensive steadicams from some suppliers, but still it is not reasonable price compared to home video equipments. I thought that it can be built easy accrding to some research so that I tried to built a hand held steadycam. The right image shows the built steadicam and the drawings can be downloaded via the link. There is no difficulty on the construction and the parts can be found at DIY store and model shop. The total cost for the parts was only ¥3,000. I think it is sufficient for home use even this cheap one.
Adjustment and Operation
Coarse adjustment: set a camera on the camera mount and balance to stand the vertical post with camera position and counter weight. Fine adjustment: decrease counter weight with adjusting camera position to a degree that the vertical post barely stands it self. When adjusted center of mass to just gimbal, force of self restoration is lost, so that the center of mass should be set to slightly lower the gimbal. In the fine adjustment, lends cap and LCD monitor must be put to operating state because it affects the balance. Finally, take handle and shake the steadicam any direction and confirm that no motion occure on the camera.
The camera works, panning and tilting, are done in adjusting camera direction with holding the vertical post at the gimbal with fingers. The stadicam has a weak point that affected by wind, so that take care when use the steadicam out door. This is due to wind pressure acts in asymmetry even if it is balanced object. To minimize skake and take a smooth video with the steadicam, you must master a skill to operate the steadicam well.
Improving Stability
Less inertia of balanced part excessively increases sensitivity of camera operation, so that adding proper dead weight will able to get good result when the camcorder is too light. However too heavy weight is not good for hand held steadicam by reason of fatigue of arms. Larger object compared at same mass (particles are far from center of mass) increase the moment of inaetia, and there is an another solution to build large in exchange fo portability.
