Hi all,
this is my autoexec.cfg:
tenshizoomcalc = [
zoomautosens 0
zoomsens (*f $sensitivity (divf (atan (*f (divf $scr_h $scr_w) (tan (divf $zoomfov 2)))) (atan (*f (divf $scr_h $scr_w) (tan (divf $fov 2))))))
]
bind "LSHIFT" [tenshizoomcalc; zoom 1; onrelease [zoom 0]]
Have fun with it!