All my lenses just doubled in length ....

Correct. Perspective is created by the Distance to your subject, whereas Crop is set by the FL, or FOV of the lens.

Using a longer FL lens, at the SAME position, is exactly the same as cropping the image.

Digital Crop, as in Digital Zoom, degrades the image quality very quickly. I am impressed how Clear Image Zoom degrades much slower. There are different levels, 1.2x, 1.5x, 2x, with 2x being worse. Still 2x is much better than Digital Zoom, and rather usable,

Yes, it can be done in PP too, but not all PP tools have good 'cropping' engines.

To the others, at SIMILAR crop, a longer FL requires a longer DISTANCE to your subject, and changes your PERSPECTIVE. This seems to have led to some confusion here. Lenses do not change perspective, distance does. A wide angle lets you typically shoot from closer, a tele from further away. Your lens choice dictates your distance, and with it the perspective.

Sony Clear Image Zoom marketing page:

http://www.sony-asia.com/microsite/assets/cyber-shot/2011h2/clear-image-zoom/

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Cheers,
Henry