The Telegraph
Since 1st March, 1999
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Comfortable click
Particle-filter cam: The new arrangement will be more comfortable than the usual one

Designers of digital cameras try to take care of everything. Unless users want more control, all they usually have to do is point and shoot. The camera does the rest: setting focus, aperture and shutter speed.

The designers at Olympus have even tried to take care of a bane of photography: dust. Deep inside the Olympus Evolt E-300 is a dust-reduction system that relies on ultrasonic vibrations to remove particles that may collect on important optical elements of this 8-megapixel digital single-lens reflex camera.

For as long as cameras have been around, they have been plagued by dust, both on the lens and within the camera body. Lens dust can be removed with careful cleaning, but internal dust has been more difficult to deal with. Professional photographers will often use two or more cameras rather than swap lenses on a single camera, because changing lenses increases the risk that dust will get inside and affect images.

Richard S. Pelkowski, a product manager for Olympus Imaging America, said digital cameras were more prone to collecting internal dust than film cameras, because of all the electronics inside. 'Digital cameras are electrical devices,' he said, and can produce electrostatic charges that attract dust particles.

In the Evolt, a small optical glass filter is positioned between the camera's shutter and its imaging chip, a charge-coupled device, or CCD. The filter is circular and set in a metal frame, which receives an electrical charge each time the camera is turned on (or activated manually from a menu on the camera's 1.8-inch liquid-crystal display). Pelkowski said the charge caused the filter to vibrate 350,000 times a second for about one-and-half seconds. This is indicated by a flickering blue light on the camera.

The jolt of electricity is produced by a tiny transformer on the camera's circuit board that steps up the voltage, Pelkowski said. The dust that is shaken off the filter falls onto strips of adhesive material where it sticks like flies to flypaper.

The result, Pelkowski said, is a practically particle-free filter, which enables the CCD to record speckle-free images. The CCD is tucked away behind an airtight seal to further protect it from dust, even the sort that is inevitably created by the workings of the camera's mechanical parts over time. (The dust strips can be replaced when the camera is cleaned and serviced.)

The Evolt E-300 is intended for serious amateur photographers who are accustomed to single-lens reflex, or SLR, designs, in which the user looks through the lens for focusing, rather than through a separate viewfinder. As a result, it has many features not found on typical point-and-shoot models. For example, its interchangeable lenses contain microprocessor chips so they can communicate directly with the camera's computer for better zoom, sharper focus and a range of other benefits.

The camera also has a lower profile than many other digital SLR cameras. It lacks the conventional SLR pentaprism, part of the eyepiece system that usually bulges above the camera top. The Evolt lowers the eyepiece closer to the level of the lens by using four mirrors to direct images seen through the lens through the camera's body.

Some photographers who have used the camera said they found the arrangement more comfortable than the usual one, which reflects the images back and up to the viewfinder. Pelkowski said the Evolt uses a side-swing mirror box (most camera mirrors swing up) to create the 'flat top' appearance.

While only about 800,000 digital SLR cameras were sold in North America last year ' a small fraction of all digital cameras sold ' features like dust-reduction filters and 'smart' lenses could help increase sales. (NYTNS)

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