For those who are looking for some help on how to parametrize the zoom features, and giving some guidance on how to use those parameters that are available at book, page and element level:
There is a
new blog post released that might help you.
Besides several tips, download links and instructions on how to "analyze"
the demo book are provided.
Parameters and topics discussed are e.g.:
zoominit, zoomdoubleclick, zoomstep, zoomminscale, zoommaxscale, gallery, hires, scale, liquid scaling, full screen