thanks a lot, 0% with gradual does work well, but 1.33 coefficient is a general setting of many cod top players so the value is more than default and should anyway have its advantage.
On the other hand, some other games, like r6s and pubg, feels more like after zoom but could also be another kind of gradual zoom. And if there are difference, the convertion of the games can't be right, at least for the first several shots after zoom. And for snipers and some guy who wants to make a headshot, this discrepancy is quite deadly. And…some games, like destiny 2, can't even get a 0% ads.
so it comes to the original question of this discussion, there should be a way, like a function or a game engine setting about fov change, to describe the change in the process of zooming in, of 360 distance, of some other value related to the fov… Maybe only the games with similar zooming in process can be "based on".