Originally posted by Erik I understand that, but this still means that if this sensor was cropped to what you might call "100 mm-e", you still often cannot get pictures with the same perspective as you could with an actual 100 mm-e lens -- so talking about a camera that functions by cropping in terms of "equivalent focal lengths" is misleading.
You're simply wrong here. If, for instance, you stand at the same point, shooting the same subject, with a 75mm lens on a FF camera and a 50mm lens on an APS-C camera, you get
exactly the same perspective. You still don't necessarily get the same
look, but that has to do with other qualities, like DoF in the image and the rendering qualities of the lenses. But the
perspective will be identical. The
only thing that matters is the distance to the object in question and thus which field of view it covers as seen from the photographers position - it's then up to the photographer to choose focal length, sensor size and amount of cropping to achieve that field of view.
I urge you to have a look at full size cityscapes shot with the 645D - if you look at 100% details they look as if they were shot with a super tele - very instructive.