Today’s post by Joe Farace
“Stability isn’t nearly so spectacular as instability.” — Aldous Huxley
In Barry Staver and my most recent Pixels, Grain and Cookies Podcast we struggled to explain how an image stabilized lens works together with an in-body stabilized camera to leverage the effect of making the image even more stabilized. Today I’m going to attempt to explain how it all works, or least I’m going to give it a good try, no matter what Yoda had to say on that topic.
In Body Stabilization (IBIS)
In-body image stabilization uses internal gyroscopic sensors to detect camera movement, then physically shifts the camera’s imaging sensor using magnetic actuators to cancel or, at least, minimize any motion in the captured image,
How it works: When you press the shutter button, small gyroscopes and accelerometers built into the camera’s body measure how much the camera is moving. A processor calculates the speed and direction of that movement and magnetic coils or motors move the sensor in the opposite direction of that motion so light hits the same spot on the sensor. It does all this in real time so if you haven’t already been impressed by how IBIS works you should be now.
An accelerometer is an electromechanical device that measures acceleration forces, vibration, and motion and converts any motion into an electrical signal.
How I Made this Photograph: I made this image in Downtown Daytona when a friend and I were exploring the seven stop image stabilization (IBIS) capability of the Olympus E-M1X. When used with Sync-IS compatible lenses, like the Olympus M.12-100mm F4.0 that I used here, it increases to 7.5 stops. This handheld exposure was four second at f/11 and ISO 200. I made an eight second exposure and it was almost but not quite as sharp. As you get older, your ability to hand hold slow shutter speeds generally decline but my young friend was able to consistently shoot sharp photos at eight and sometimes at 16 seconds using the same camera setup.
In Lens Stabilization (IS)
In-lens image stabilization is often called Optical Image Stabilization (OIS) or vibration reduction (VR) and moves an internal floating glass element in the opposite direction of any detected camera movement keeping the light steadily focused on the sensor.
How it works: Built-in gyro sensors or accelerometers inside the lens barrel continuously measure any physical movements, such as pitch (up and down) and yaw (side to side.) A microprocessor located inside the lens analyzes the speed and angle of any motion. Then it sends electrical current to coils, that shift that floating element in the opposite direction of the motion while Hall Effect sensors monitor this movement to ensure it matches the movement. Once again all this is carried out in real time.
A Hall-effect sensor is an electronic device that detects the presence, strength, and polarity of a magnetic field and converts it into an electrical signal.
How They Work Together
Optical In-lens stabilization and IBIS work together by dividing the job of correcting camera movement across different axes and focal lengths, communicating in real-time through the camera’s processor. When paired together, the camera and lens communicate so OIS handles angular shake and macro corrections, while IBIS tackles roll and linear shifts that a lens element can’t handle. Combining them doesn’t add their individual stop ratings together but typically produces additional stops of handheld performance than could not be accomplished by either system individually, especially in low light or when using slower shutter speeds as I mentioned in the podcast.
PS: While I’ve explained what it does when the two stabilization systems work together, I still don’t know how that division of labor is accomplished. I’m betting that how each camera manufacturer accomplishes this tricky work, is proprietary.
Barry Staver and Joe Farace are co-authors of Better Available Light Digital Photography that may be an oldie but, I think anyway, that it’s a goodie. New copies are $19.90 with used copies starting around ten bucks from Amazon.