Optical zoom and size are generally hand in hand, since bigger zoom means a bigger lens means a bigger chassis. However, there are some models that avoid this by using different focusing equipment or different lenses. Simply put, you
can get a compact camera with great optical zoom,
like this one. I own an earlier generation of this series and it's done fine by me, and most reviewers seem to like it as well.
As to your concerns about zooming in video mode, all modern digital cameras should have this feature, so don't worry about it. Graininess at high ISO levels seems standard run for any camera that's just point-and-shoot, so take that as you will.
Jam it back in, in the dark.
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Sol