set zoom_in "cg_fov 50;sensitivity 4"
set zoom_out "cg_fov 100;sensitivity 8"

OR

set zoom_in "cg_fov 50;sensitivity 8"
set zoom_out "cg_fov 100;sensitivity 8"

OR

set zoom_in "cg_fov 50;sensitivity 16"
set zoom_out "cg_fov 100;sensitivity 8"

or something completely different?

I am normally using the first one but its kind of feeling a bit low sens, and then i wondered if i'm doing it right at all, also because i'm gonna make the zoomfov less it would be nice to know which method is the correct one, obviously i want the sens to feel the same while zooming, but i'm not sure what others do, if they just find some value that feels good or if they calculate it like i did. :)