Re: EOS: IR & IS in TC: WAS Canon's Infinite Wisdom

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On 14 Jan 98 at 15:33, Herb Schulz wrote:

> The IS system works by measuring the acceleration of the lens body as it
> wiggles around.  The acceleration, for a given angular speed of wiggle is
> proportional to the radius to the center of the rotation.  Therefore the
> accelerometers (gyros, whatever) work better when they are further from the
> body.  Of course there are other considerations, like where the mechanism
> will fit inside the lens, etc.

Everyone seems to overlook the fact that gyro sensors don't detect
linear motion, but angular motion....in which case it doesn't matter 
much where the sensor is located. This is consistent with what is 
written in CLW II, page 186:

"Camera shake is detected by two gyro sensors (one each for the yaw 
and pitch). Shown in Photo 27, thye gyro sensos detect the angle and 
speed of the camera shake caused by handheld shooting." 

Btw, as an IR photographer I am a bit disturbed by the fact that
they mention the use of  " IRED's " (InfraRed Emitting Diodes) for
detection of the actual IS lens group position. 

The core question: Is there any other advantage to IR LED's than that
they are not visible? If being not visible is the only reason, then I
can assume that Canon at least thought it *possible* that visible
light made it into the final image, if not very *likely*?....hence
they did not *want* to use visible LED's? 

Willem (invisibly shaking, in spite of IS) Jan


- -- 
Bye,

Willem-Jan Markerink


      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]
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