Coming up with a dust reduction system
Keeping dust from adhering to the CCD is a major issue. Some
professional photographers always point their camera downward when changing lenses,
and change them as quickly as possible, while others never change lenses at all
while out on a shoot. Because this is such an issue, all camera manufacturers
are under pressure to come up with the best solution.
"We had to do something, and do something fast,"says Sumio Kawai. Kawai, who
has been involved with camera development since the interchangeable lens design
of the OM system, grappled with this issue. "Then I remembered the ultrasonic
vibrations I had used in my work before. I slapped my forehead, it was so obvious.
I was confident that ultrasonic vibrations would do the trick, and set about thinking
of a concrete method for achieving it."
The system would need to remove all kinds of dust and debris, and so tests were
run under a multitude of imagined environments, including salt, metal dust, fine
dirt, and more.
It was also proposed that since it was a digital camera, there was no reason why
they could not remove debris at the image processing stage. That proposal, however,
was rejected immediately. "That's impossible," states Mori categorically. "There
will always be a trace left where processing took place, so the picture will appear
unnatural. I consider this type of processing to be an absolute no-no for a camera
of the E-1's class."
All expectations then focused on the ultrasound method proposed by Kawai. Specifically,
this solution vibrates the optical glass filter in the ultrasound frequency range,
removing dust and debris, but humans cannot perceive the vibration. If an object
vibrates 20,000 times per second, or in other words with a frequency of 20 kilohertz
or higher, our ears cannot hear it.
A chorus of oohs and ahs was heard at the press conference when the image of a
single speck of dust was shown slipping off the filter. The reporter's questions
were also focused on this dust reduction system.
But "Although we were asked a lot of questions about the dust reduction system,"
says Kawai, "a lot of the information is confidential, so we couldn't go into
detail about the construction. It was very painful for me to have to beat around
the bush, without being able to give straight answers."
What is clear is the following point mentioned by project-leader Asakura: "Dust
reduction systems will be one of the key factors behind victory and defeat for
future digital SLRs."
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Sumio Kawai
Imaging System Group
R&D-2 Department, R&D Division
OLYMPUS CORPORATION
Worked on the development of the Four Thirds system and dust reduction system, two of the main features of the E-1. His work has always involved cameras, and photography is his hobby. |
