Image stabilization (IS) is a family of techniques that reduce blurring associated with the motion of a camera or other imaging device during exposure.
Generally, it compensates for pan and tilt (angular movement, equivalent to yaw and pitch) of the imaging device, though electronic image stabilization can also compensate for rotation about the optical axis (roll). It is mainly used in high-end image-stabilized binoculars, still and video cameras, astronomical telescopes, and also smartphones. With still cameras, camera shake is a particular problem at slow shutter speeds or with long focal length lenses (telephoto or zoom). With video cameras, camera shake causes visible frame-to-frame jitter in the recorded video. In astronomy, the problem of lens shake is added to variation in the atmosphere, which changes the apparent positions of objects over time.
Application in still photography
In photography, image stabilization can facilitate shutter speeds 2 to 5.5 stops slower (exposures 4 to 30 times longer), and even slower effective speeds have been reported.
A rule of thumb to determine the slowest shutter speed possible for hand-holding without noticeable blur due to camera shake is to take the reciprocal of the 35 mm equivalent focal length of the lens, also known as the "1/mm rule". For example, at a focal length of 125 mm on a 35 mm camera, vibration or camera shake could affect sharpness if the shutter speed is slower than second. As a result of the 2-to-4.5-stops slower shutter speeds allowed by IS, an image taken at second speed with an ordinary lens could be taken at or second with an IS-equipped lens and produce almost the same quality. The sharpness obtainable at a given speed can increase dramatically. When calculating the effective focal length, it is important to take into account the image format a camera uses. For example, many digital SLR cameras use an image sensor that is , , or the size of a 35 mm film frame. This means that the 35 mm frame is 1.5, 1.6, or 2 times the size of the digital sensor. The latter values are referred to as the crop factor, field-of-view crop factor, focal-length multiplier, or format factor. On a 2× crop factor camera, for instance, a 50 mm lens produces the same field of view as a 100 mm lens used on a 35 mm film camera, and can typically be handheld at second.
However, image stabilization does not prevent motion blur caused by the movement of the subject or by extreme movements of the camera. Image stabilization is only designed for and capable of reducing blur that results from normal, minute shaking of a lens due to hand-held shooting. Some lenses and camera bodies include a secondary panning mode or a more aggressive 'active mode', both described in greater detail below under optical image stabilization.
Astrophotography makes much use of long-exposure photography, which requires the camera to be fixed in place. However, fastening it to the Earth is not enough, since the Earth rotates. The Pentax K-5 and K-r, when equipped with the O-GPS1 GPS accessory for position data, can use their sensor-shift capability to reduce the resulting star trails.PENTAX O-GPS1 - News Release, Pentax.jp (archived)
Stabilization can be applied in the lens, the camera body or both. Each method has distinctive advantages and disadvantages.
Techniques Optical image stabilization
An optical image stabilizer (OIS, IS, or OS) is a mechanism used in still or video cameras that stabilizes the recorded image by varying the optical path to the sensor. This technology is implemented in the lens itself, as distinct from in-body image stabilization (IBIS), which operates by moving the sensor as the final element in the optical path. The key element of all optical stabilization systems is that they stabilize the image projected on the sensor before the sensor converts the image into digital information. IBIS can have up to 5 axis of movement: X, Y, Roll, Yaw, and Pitch. IBIS has the added advantage of working with all lenses.
Benefits of OIS Optical image stabilization prolongs the shutter speed possible for handheld photography by reducing the likelihood of blurring the image from shake during the same exposure time.
For handheld video recording, regardless of lighting conditions, optical image stabilization compensates for minor shakes whose appearance magnifies when watched on a large display such as a television set or computer monitor.
Names by vendors Different companies have different names for the OIS technology, for example: Vibration Reduction (VR) – Nikon (produced the first optical two-axis stabilized lens, a 38–105 mm zoom built into the Nikon Zoom 700VR (US: Zoom-Touch 105 VR) camera in 1994)Nikon camera models 1992-1994 MIRNikon Zoom 700VR Camera Gossip Image Stabilizer (IS) – Canon introduced the EF 75–300 mm f/4–5.6 IS USM) in 1995. In 2009, they introduced their first lens (the EF 100mm F2.8 Macro L) to use a four-axis Hybrid IS.) Anti-Shake (AS) – Minolta and Konica Minolta (Minolta introduced the first sensor-based two-axis image stabilizer with the DiMAGE A1 in 2003) Optical SteadyShot (OSS) – Sony (for Cyber-shot and several α E-mount lenses) Optical Image Stabilization (OIS) – Fujifilm MegaOIS, PowerOIS – Panasonic and Leica SteadyShot (SS), Super SteadyShot (SSS), SteadyShot INSIDE (SSI) – Sony (based on Konica Minolta's Anti-Shake originally, Sony introduced a 2-axis full-frame variant for the DSLR-A900 in 2008 and a 5-axis stabilizer for the full-frame ILCE-7M2 in 2014) Optical Stabilization (OS) – Sigma Vibration Compensation (VC) – Tamron Shake Reduction (SR) – Pentax PureView – Nokia (produced the first cell phone optical stabilised sensor, built into the Lumia 920) UltraPixel – HTC (Image Stabilization is only available for the 2013 HTC One & 2016 HTC 10 with UltraPixel. It is not available for the HTC One (M8) or HTC Butterfly S, which also have UltraPixel) Most high-end smartphones as of late 2014 use optical image stabilization for photos and videos.
Lens-based In Nikon and Canon's implementation, it works by using a floating lens element that is moved orthogonally to the optical axis of the lens using electromagnets.What is Optical Image Stabilizer? , Technology FAQ, Canon Broadcast Equipment Vibration is detected using two piezoelectric angular velocity sensors (often called gyroscopic sensors), one to detect horizontal movement and the other to detect vertical movement.Glossary : Optical : Image Stabilization, Vincent Bockaert, Digital Photography Review As a result, this kind of image stabilizer corrects only for pitch and yaw axis rotations, and cannot correct for rotation around the optical axis. Some lenses have a secondary mode that counteracts vertical-only camera shake. This mode is useful when using a panning technique. Some such lenses activate it automatically; others use a switch on the lens.
To compensate for camera shake in shooting video while walking, Panasonic introduced Power Hybrid OIS+ with five-axis correction: axis rotation, horizontal rotation, vertical rotation, and horizontal and vertical motion.
Some Nikon VR-enabled lenses offer an "active" mode for shooting from a moving vehicle, such as a car or boat, which is supposed to correct for larger shakes than the "normal" mode. However, active mode used for normal shooting can produce poorer results than normal mode. This is because active mode is optimized for reducing higher angular velocity movements (typically when shooting from a heavily moving platform using faster shutter speeds), where normal mode tries to reduce lower angular velocity movements over a larger amplitude and timeframe (typically body and hand movement when standing on a stationary or slowly moving platform while using slower shutter speeds).
Most manufacturers suggest that the IS feature of a lens be turned off when the lens is mounted on a tripod as it can cause erratic results and is generally unnecessary. Many modern image stabilization lenses (notably Canon's more recent IS lenses) are able to auto-detect that they are tripod-mounted (as a result of extremely low vibration readings) and disable IS automatically to prevent this and any consequent image quality reduction. The system also draws battery power, so deactivating it when not needed extends the battery charge.
A disadvantage of lens-based image stabilization is cost. Each lens requires its own image stabilization system. Also, not every lens is available in an image-stabilized version. This is often the case for fast primes and wide-angle lenses. However, the fastest lens with image stabilisation is the Nocticron with a speed of f/1.2. While the most obvious advantage for image stabilization lies with longer focal lengths, even normal and wide-angle lenses benefit from it in low-light applications. Sensor-shift
The sensor capturing the image can be moved in such a way as to counteract the motion of the camera, a technology often referred to as mechanical image stabilization. When the camera rotates, causing angular error, gyroscopes encode information to the actuator that moves the sensor. The sensor is moved to maintain the projection of the image onto the image plane, which is a function of the focal length of the lens being used. Modern cameras can automatically acquire focal length information from modern lenses made for that camera. Minolta and Konica Minolta used a technique called Anti-Shake (AS) now marketed as SteadyShot (SS) in the Sony α line and Shake Reduction (SR) in the Pentax K-series and Q series cameras, which relies on a very precise angular rate sensor to detect camera motion.Dynax 7D Anti-Shake Technology , Konica Minolta Olympus introduced image stabilization with their E-510 D-SLR body, employing a system built around their Supersonic Wave Drive. Other manufacturers use digital signal processors (DSP) to analyze the image on the fly and then move the sensor appropriately. Sensor shifting is also used in some cameras by Fujifilm, Samsung, Casio Exilim and Ricoh Caplio.
The advantage with moving the image sensor, instead of the lens, is that the image can be stabilized even on lenses made without stabilization. This may allow the stabilization to work with many otherwise-unstabilized lenses, and reduces the weight and complexity of the lenses. Further, when sensor-based image stabilization technology improves, it requires replacing only the camera to take advantage of the improvements, which is typically far less expensive than replacing all existing lenses if relying on lens-based image stabilization. Some sensor-based image stabilization implementations are capable of correcting camera roll rotation, a motion that is easily excited by pressing the shutter button. No lens-based system can address this potential source of image blur. A by-product of available "roll" compensation is that the camera can automatically correct for tilted horizons in the optical domain, provided it is equipped with an electronic spirit level, such as the Pentax K-7/K-5 cameras.
One of the primary disadvantages of moving the image sensor itself is that the image projected to the viewfinder is not stabilized. Similarly, the image projected to a phase-detection autofocus system that is not part of the image sensor, if used, is not stabilized. This is not an issue on cameras that use an electronic viewfinder (EVF), since the image projected on that viewfinder is taken from the image sensor itself.