Does anyone KNOW what the image circle is for each of the EF-S lenses currently available? Likewise, the maximum distance between the lens mount flange and the rear protrusion of the lens (this will vary with zoom/focus distance)? It occurs to me that Canon may have designed these lenses so they provide adequate coverage on a 1.3 crop sensor, and that a double motion mirror (as originally seen on the first Digital Rebel) might allow clearance of the rear element. The more complicated mirror movement would act as a limitation on maximum frame rate achieveable. However, it could allow a 20D successor to remain EF-S compatible while having a 1.3 crop sensor. It would also offer some comfort to those investing in EF-S glass who feel that they might consider a 1.3 crop in the future if it is offered (as seems likely from Canon's statements about the future of 1.3 crop - it will disappear from the 1 series, but not completely from the EOS line).