I remember this from FO3. Thanks for refreshing my memory. Thought I'd pitch with a couple lines in case I'm not the only one with this past annoyance:
One of the more annoying things since I started playing was the zoom transition delay between vanity and first person view. Did some testing and found some lines in the generated INI that remedy this.
Higher value faster zooming. Additionally to faster mouse wheel scrolling, it will switch faster from zoomed out third person to first person using the default F-key
Original: fMouseWheelZoomSpeed=0.8000Mod: fMouseWheelZoomSpeed=2.4000
After changing this, you should also alter the value of zooming increments.
Original: fMouseWheelZoomIncrement=0.0750Mod: fMouseWheelZoomIncrement=0.0320
Lower value = http://forums.bethsoft.com/topic/1274769-open-console-saveini-intresting-read/lower increments
Camera now switches a LOT faster than original while still retaining the constant fluid motion of transitioning. Using the scroll wheel to zoom in / out is also a lot more responsive and accurate.
There are a lot more interesting lines in the [Camera] section, like;
fShoulderDollySpeed=3.0000 "Controls the camera transition between holstered / drawn weapon. Lower value = http://forums.bethsoft.com/topic/1274769-open-console-saveini-intresting-read/slower transition"fOverShoulderCombatPosZ=20.0000 "Vertical orientation of the vanity cam, drawn weapon. Positive value moves the camera higher. Negative value the opposite"fOverShoulderCombatPosX=0.0000 "Horizontal orientation of the vanity cam, drawn weapon. Positive value moves camera to the left of the character. Negative value moves it to the right of the character"fOverShoulderPosZ=-10.0000 "Vertical orientation of the vanity cam, holstered weapon. Values behave identically as above."fOverShoulderPosX=30.0000 "Horizontal orientation of the vanity cam, holstered weapon"fVanityModeMinDist=155.0000 "Governs how close you may zoom vanity camera before it switches to first person camera. Lower value = http://forums.bethsoft.com/topic/1274769-open-console-saveini-intresting-read/closer, although a too low value will make camera start clipping into the player and the transparency / ghost effect will take effect"
In response to LadyCrimson, that would be the AutoVanityMode under [Camera] section. Theres a setting that presumptively should disable it, "bDisableAutoVanityMode=0", though I've not tested it myself. A sure fix would be setting the fAutoVanityModeDelay value to some absurdly high number. I've read reports that this line works. The default value should be 120, which are values in seconds. Setting this to 3600 - one hour - (or even higher) is one way to extend the time for it to kick in.