I possibly should find a graphics forum but I lazy and hope someone here will know this:
There is a method of navigating/zooming which is used in some graphics programmes, also in Adobe Acrobat.
Some people say it's difficult to learn (it's mostly useful for graphics) but it is highly efficient, and a PIA when it doesnt work.
Here's a quick image of keys / combinations.
 mouse-click needed for zoom to work (incremental). Alternatively Click n Drag to select area to zoom into/out-of
the beauty of it is that you can fluidly move between all these options by pressing or de-pressing one or more of the keys.
Ctrl = pointer
add Spacebar = Zoom in
add Alt = Zoom out
keep Spacebar pressed and release others = Pan/Hand
this was broken in Acrobat 9 AFAIK (edit: I'm not sure now - it's possible I upgraded from 8 to 10)
They decided to spruce it up in version 10, which I hate, but could live with if it worked properly - but it doesnt (going from Ctrl+Space to just Space leaves you with Zoom in
instead of Pan
 Does anyone know if it works in Acrobat 8 (I cant remember)
 Wondering is it dangerous these days to use older versions of Actobat as default PDF opener (if so, I think
can have two versions installed).