Look what I just found:

http://forum.symthic.com/battlefield-4-technical-discussion/7836-cte-uniform-soldier-aiming-info/When the coefficient C = 0, then the formula used to calculate a sight's sensitivity factor is: SensFactor = tan(ZoomFov/2)/tan(HipFov/2)

At this setting, the formula acts to make the "mouse velocity to linear screen center velocity ratio" constant. What that means is that if you could measure the velocity of the image where it passes the screen center, when moving the mouse at a constant speed, between two different FOVs, there would be no change.

When the coefficient is C > 0, then the formula is SensFactor = atan(tan(ZoomFov/2)*C) / atan(tan(HipFov/2)*C)

To understand where this formula comes from, the original idea was to use the formula ZoomFov/HipFov to synchronize the "mouse distance to half FOV angle turn" number to make it constant for all scopes. What that would do would be to make it so that it would take the same mouse movement to move something at the top edge center of your screen to your cross hairs, no matter what FOV you were at.

When this formula was converted to work on synchronizing the horizontal mouse distance to half FOV angle turn number, the following equation was obtained:

SensFactor = atan(tan(ZoomFov/2)*W/H) / atan(tan(HipFov/2)*W/H)

Where W is screen Width

And H is Screen Height

Which means the current formula replaces W/H with C.

So if C = W/H, the horisontal half FOV turn distance will be constant.

Of course, my measurements aren't extremely precise, but...

tan(0.522/2)/tan(1.492/2) =

**0.289** and I got

**0.291**tan(1.381/2)/tan(1.492/2) =

**0.894** and I got

**0.896**That guy might be right, but he also says:

C = 4/3 (New default)

This is the best working value we have found so far. Incidentally, it's the same value used in counter-strike games!

C = 4/3 makes all the scopes feel the same speed, and should provide a good sensitivity relationship to maintain drag shooting muscle memory across sights too.

Then why is 178% closer to 1:1:1 than 133%? Why do we get the same results for c = 0 and not for c > 0??