Got it, thanks for the follow up.
The risk in equating zoom number to picture size is how imprecise it is.
Using the Q6044 above for example, if I say 30X makes my picture 30 times bigger I am not clearly expressing/ignoring the FoV width change. This may be obvious to someone with experience, but a novice may not understand this - especially given how careless marketers use this number.
Even when used for calculations, it can be a bad metric to use. Again, the Q6044 has a 62.9 degree wide FoV width at the shortest focal value.
Multiplying that widest FoV by (1/30), or 30X less returns 2.09mm. To get the actual claimed 2.2mm, we need to use 28.
So is the 'zoom number' 30X, 29X, or 28X?
As long as we make sure we are only using it for focal length values, there is no risk, but since it is open for rounding errors, using this number to calculate FoV size is problematic.