Sensor Dust Shield

today I cam across a piece called "Dust Shield". It's a transparant piece you position at your Dslr between the mirror and the lens. Here is a video how it's done.

http://www.youtube.com/watch?v=dxmsI...layer_embedded

The website tells it's only available for the Canon 5d and 5d mark II yet.

Is it really that easy to avoid dust on your sensor? It sounds a bit too easy for me, than why wouldn't every camera be equipped with it anyway? I wonder what the Dust - Shield would do to your image quality.

What would be your thoughts about it? Or is there anyone using this already?

I came across this product sometime in 2009. And I also remember thinking to myself, this is a novel idea. But why don't dSLR companies like Nikon and Canon (the big 2) incorporatethis into their cameras? Is it because they adopt a very traditional and conservative policy, or is it because they don't see a need to change? However, Pentax, Sony and other companies also did not buy into this idea. Besides, even after several years since it was founded, this company never really made it big. So I also asked myself, why hasn't their products take off? I'm afraid I cannot provide an answer to your question. :(

Despite my skepticism towards dust shield, I would like to believe that it is a practical solution to the problem of dust entering the body. However, I'm worried that it might hit the shutter and/or rear element of the lens. Also, if the lens does not have a retro-focus design, this dust shield can disperse light and introduce chromatic aberration.