Some digicams like the Sony T series and Nikon S series have optical zooms but yet the lens does not extend outwards like all other models in Canon.

Is this a patented design?

But my main question is, is there any diff in image quality whether the lens extends or not?

If the zooms can be made so compact, wonder why Canon or other brands are still not into it yet.

Hope those with experience in the comparison can comment. Thanks!