Curious. Just tested on my A570:
In movie mode without recording, can zoom from optical to digital without releasing lever (there is a pause in the zooming though) and same with returning from digital to optical.
While recording though, the zoom is continuous from optical to digital , but when returning from digital, the lever must be released to resume zooming out optical.
Conversely, in the photo modes, it's the opposite. When zooming from optical to digital , the lever must be released and re-engaged, on return, it is continuous.
-tgq
