Hi Phil,
This one is a ZoomPosition in steps within the available ZoomRange from widest '0' to longest '255'.
It is not very precise.
for example on a 12-60mm
you get a '3' ~ '5' knocked on the 12mm
and a '250'~'252' hard on the 60mm.
But on some cams with embedded lenses you can get full range of '0'-'255'.
Sad is, that ZS200 use a range of '0..128'.
But rounded to full 'mm' the formula
MinFocalLen + (MaxFocalLen-MinFocalLen) * ZoomRange
is always the current focallength given from other tags.
(for verify only).
-Klaus
Thanks. Added.