First there are two "ZOOM" functions used on TV's One is the one that expands NTSC Video to wide screen (Clips top and bottom) (As I type this I'm litenign to WRCJFM.ORG and I do think I know the music, Darling daughter played it in High School) Back to topic.
Or it can go either into several other modes.
The other is a "Zoom into area" type function.. Kind of like zooming in Google Maps.. And if you have this on the pic will NEVER all fit.
IF your pic size has either an Automatic (Set by station) or "Natura' Choose it and make sure all other zooms are set Normal/Off as well.
I don't do VIZO specific cause I have helped with a couple and they were a pain.