Automatic sensor cleaning

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As automatic sensor cleaning (also: anti-dust system , dust protection system ; English Dust Removal System , Dust Reduction System ) refers to technologies that are in digital SLR cameras , the problem of dust on the (SLRs) image sensor to solve.

Dust build-up

Every time the lens is changed, there is a possibility that dust or other foreign particles will get into the camera housing and deposit on the image sensor. But even if the camera is not opened, the smallest particles can be released inside the camera and stick to the sensor. This can be caused by mechanical abrasion from moving components (for example, the shutter or swing-back mirror ). With zoom lenses , depending on the design, air and thus also dust can be sucked into the interior of the camera when the zoom is operated.

With SLRs that work with film , this is hardly a problem, since the dirt is transported on with the film. It is different with digital SLRs: if they are deposited on the sensor, even microscopic particles 0.1 mm in size can become visible as gray spots on all images subsequently recorded. Attempts to clean with commercially available cleaning kits always involve the risk of damaging the sensor. So there is often only the - mostly chargeable - use of the manufacturer's service for sensor cleaning.

Dust particles can stick to the sensor for two reasons: due to electrostatic charge and due to intermolecular attraction .

Dust particle deposition due to electrostatic charging

Most of the dirt on the image sensor consists of particles approximately 1 µm (0.001 mm) in size that are adhered by static electricity. The particles carry a positive electrical charge , whereas the sensor is negatively charged, so both attract each other. A similar phenomenon can be observed on the surface of CRT or LCD monitors.

Dust particle deposition through molecular attraction

The forces of attraction between molecules are not as strong as the electrostatic ones. But they are sufficient to hold microscopic particles, such as drops of moisture, on the sensor surface. In contrast to electrostatic charges, grounding does not help. Since the molecules adhere very closely to the adhesion surface, they are also more difficult to remove by dust protection systems. However, this problem rarely occurs.

functionality

In general, the automatic sensor cleaning is based on the fact that possible dust on the sensor of the DSLR is "shaken off" by high-frequency (e.g. EOS Integrated Cleaning System) vibrations. Different manufacturers use different methods for this.

Manufacturer

The problem of dust build-up on image sensors of digital SLRs was first addressed by Olympus . Olympus equipped its first D-SLR, the E-1 , with its supersonic wave filter back in 2003 . Other manufacturers such as Canon , Pentax and Sony followed with their own developments. Panasonic and Leica, on the other hand, use the Olympus dust protection system.

Problems

Because the dust adheres to the sensor with the help of electrostatic charges, it is not always possible to completely remove all particles. In addition, particles removed from the sensor remain in the housing and can adhere again. With the Olympus Supersonic Wave Filter dust protection system, on the other hand, removed dust is collected in a specially designed dust collection unit.

Web links

Individual evidence

  1. ↑ http://www.digital-slr-guide.com/digital-slr-sensor-dust.html
  2. ↑ http://www.digiklix.de/2007/02/13/test-reinigungsset-fuer-kamera-sensoren-sensorreinigung/ cleaning kits
  3. ↑ http://www.canon.de/for_home/product_finder/cameras/digital_slr/technologies_features/self-cleaning.aspx
  4. ↑ http://www.digitalkamera.de/Meldung/Wie_effektiv_ist_die_automatische_Sensorreinigung/4114.aspx