Supersonic Wave Filter
Encyclopedia
The Supersonic Wave Filter (SSWF) is a dust reduction system
developed by Olympus
to overcome the negative effect of dust particles landing on the image sensor
of digital SLRs
. DSLRs are particularly vulnerable to this issue, since the interior of the camera is exposed during lens changes unlike other forms of digital camera
s, and the image sensor is fixed, unlike a film camera. Even the tiniest (micrometre-size) dust particles or other contaminants that settle on the face of the image sensor (individual pixels of which have dimensions on the order of ~5 micrometres) may cast shadows and thus become visible in the final image as more or less diffuse grey blobs, depending on aperture.
The system consists of a very thin piece of filter glass placed in front of the image sensor; the area between the filter and the sensor is sealed, so no dust can enter. Whenever the camera is turned on, a piezoelectric driver induces a vibration in the filter glass, shaking dust off. A piece of adhesive located inside the camera traps removed dust.
The distance between the filter glass and the sensor also mitigates the problem of dust, since any dust that does adhere to the glass will be held further away from the sensor, and thus produce a larger, more diffuse, and less noticeable shadow. In practice, few Four Thirds users report having any issues with sensor dust.
The SSWF has been included in all Olympus, Panasonic, and Leica Four Thirds DSLRs, and is often cited as a key advantage of the system by reviewers and users. One disadvantage to the implementation on all current Four Thirds cameras is that the SSWF is triggered whenever the camera is turned on, causing a delay of about 0.8 seconds before the camera is ready to shoot.
Dust reduction system
A dust reduction system, or dust removal system, is a technology employed by several manufacturers of digital system cameras to solve the problem of dust particles adhering to the image sensor. Some systems remove or clean the sensor by vibrating at a very high frequency—between 100hertz and...
developed by Olympus
Olympus Corporation
is a Japan-based manufacturer of optics and reprography products. Olympus was established on 12 October 1919, initially specializing in microscope and thermometer businesses. Its global headquarters are in Shinjuku, Tokyo, Japan, while its USA operations are based in Center Valley, Pennsylvania,...
to overcome the negative effect of dust particles landing on the image sensor
Image sensor
An image sensor is a device that converts an optical image into an electronic signal. It is used mostly in digital cameras and other imaging devices...
of digital SLRs
Digital single-lens reflex camera
Most digital single-lens reflex cameras are digital cameras that use a mechanical mirror system and pentaprism to direct light from the lens to an optical viewfinder on the back of the camera....
. DSLRs are particularly vulnerable to this issue, since the interior of the camera is exposed during lens changes unlike other forms of digital camera
Digital camera
A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...
s, and the image sensor is fixed, unlike a film camera. Even the tiniest (micrometre-size) dust particles or other contaminants that settle on the face of the image sensor (individual pixels of which have dimensions on the order of ~5 micrometres) may cast shadows and thus become visible in the final image as more or less diffuse grey blobs, depending on aperture.
The system consists of a very thin piece of filter glass placed in front of the image sensor; the area between the filter and the sensor is sealed, so no dust can enter. Whenever the camera is turned on, a piezoelectric driver induces a vibration in the filter glass, shaking dust off. A piece of adhesive located inside the camera traps removed dust.
The distance between the filter glass and the sensor also mitigates the problem of dust, since any dust that does adhere to the glass will be held further away from the sensor, and thus produce a larger, more diffuse, and less noticeable shadow. In practice, few Four Thirds users report having any issues with sensor dust.
The SSWF has been included in all Olympus, Panasonic, and Leica Four Thirds DSLRs, and is often cited as a key advantage of the system by reviewers and users. One disadvantage to the implementation on all current Four Thirds cameras is that the SSWF is triggered whenever the camera is turned on, causing a delay of about 0.8 seconds before the camera is ready to shoot.