How Does Image Stabilization Work?

This article provides an introduction to camera and lens-based stabilization systems, and how to use them to improve your videos.

There are various ways for a videographer to stabilize their footage. If your camera doesn’t need to move, a tripod is ideal. Where camera movement is required, devices such as a gimbal or Steadicam will ensure that your movement is free from bumps and jolts.

But what if you can’t afford that equipment, or you need to need to be able to run-and-gun to capture your subject? The shaky camera-work that can arise from hand-holding your camera is, at best, distracting and can even be nausea-inducing for your audience. In these circumstances, the image stabilization options that may be available on your camera can save the day.

Still Photography vs Video

In the world of still photography, image stabilization is used to ensure sharp images when using slower shutter speeds. For videographers, this is not an issue–as shutter speeds of 1/48th and 1/60th second are the norm and the resulting motion blur on individual frames can actually improve the appearance of motion in your footage. However, image stabilization systems are still ideal for mitigating the unsteadiness of handheld footage.

Image stabilization comes in three forms: optical, sensor-shift and digital.

1. Optical stabilization

Optical stabilization systems are built into some lenses and work by incorporating a floating lens element, which moves to compensate for camera shakiness. Gyro-sensors detect and relay the motion to a microcomputer which controls motors that shift the floating element so as to counteract the movement of the camera.

The main advantage of optical stabilization is that, as it is built into the lens, it will work on any compatible camera. Optical stabilization is also able to compensate for greater movements than sensor-shift stabilization and so is more effective with longer telephoto lenses.

Opitical and sensor-shift stabilization systems are the best options for stabilizing your image. The sensor-shift system in the GH5 can work in conjunction with an optical system, giving you the best of both.
Optical and sensor-shift stabilization systems are the best options for stabilizing your image. The sensor-shift system in the GH5 can work in conjunction with an optical system, giving you the best of both.

Stabilized lenses, however, are more expensive and heavier than non-stabilized versions. There are also limitations on the range of movements for which lens-based stabilization systems can compensate. Typically, in-lens stabilization systems only compensate for movement along two axes: pitch (vertical tilting or pivoting movement) and yaw (side-to-side pivoting motion). Furthermore, as optical stabilization involves moving elements within the lens, it can adversely affect the quality of the bokeh in the image.

2. Sensor-shift

In-body, or sensor shift, stabilization works on the same principle as lens-based optical stabilization, though, in this case, the technology is built into the camera body. Gyros are again used to relay information about the camera’s movement to a microprocessor which controls motors to move the camera’s image sensor to compensate for shake or wobble.

The main advantage with in-body stabilization is that all lenses used with that camera will benefit from the stabilization, even older mechanical lenses. Sensor-shift based systems can also compensate for types of motion that cannot be countered with lens-based stabilization. Some cameras offer up to five axes of stabilization, including roll (rotation around the lens axis), x-axis (horizontal) and y-axis (vertical) stabilization in addition to the pitch and yaw countered by optical stabilization.

The Panasonic Lumix GH5 includes a Dual IS that incorporates sensor-shift stabilization that works in conjunction with lens-based systems to maximize the stabilizing effect.

3. Digital stabilization

Digital stabilization, also known as electronic image stabilization, is an in-camera version of the image stabilization that is included with some non-linear editing software. Rather than using the full area of the camera’s image sensing chip to record an image, a digital stabilization system only uses around 90 percent in the centre of the chip. When camera movement is detected, the portion of the image sensor used to record the image shifts in the opposite direction to compensate for the motion. The movement can be detected with motion detectors as with an optical and sensor-shift stabilization system or through an analysis of the image itself.

As digital stabilization involves cropping the sensor used to capture an image, it can lead to a loss of resolution. Also, systems that work by analyzing the image can be fooled by moving subjects in the frame or by camera movements such as panning or tilting, resulting in juddering of the image.

4. Tips for a Stable Image

While image stabilization systems can be very useful to smooth handheld footage, they can cause issues when using a camera on a tripod and so should be switched off.

When using stabilized lenses with some cameras to shoot video, the stabilization system may not be activated until you press record, possibly causing a momentary jitter in the image. If this is an issue, remember to allow a second or two at the start of each shot for the stabilization system to settle.

When shooting handheld, image stabilization can help you capture smooth tracking shots, but if you move to a tripod, it’s best to turn image stabilization off to avoid unwanted juddering in the image during pans and tilts.
When shooting handheld, image stabilization can help you capture smooth tracking shots, but if you move to a tripod, it’s best to turn image stabilization off to avoid unwanted juddering in the image during pans and tilts.

In addition to general stabilization, some systems include different operating modes such as switching off the stabilization on one axis to avoid the issues that can arise when panning or tilting the camera.

Conclusion

Image stabilization systems are very useful in reducing camera shake when shooting handheld and, with practice, you can learn to achieve smooth tracking shots. While they will never be able to replicate the floating glide that can be achieved with a Steadicam or gimbal, image stabilization systems are another great tool to help improve your video footage.

Pete Tomkies is a freelance cinematographer and camera operator from Manchester, UK. He also produces and directs short films under the name Duck66 Films.

Pete Tomkies
Pete Tomkies is a freelance cinematographer and camera operator from Manchester, UK. He also produces and directs short films as Duck66 Films.Pete's latest short Once Bitten... won 15 awards and was selected for 105 film festivals around the world.

LEAVE A REPLY

Please enter your comment!
Please enter your name here