Can someone help me understand this? (CFrames)

http://gyazo.com/e6e151c996e0fe54dff0603fe0a07f36

You will see that when I zoom in completely and move around, my arms sway. They aren't supposed to. They're supposed to stay fixed like they are when you see me zooming out and turning.

I don't understand why it's acting differently while in first person.

This is the piece of code that deals with the head's lookVector (arms are bound to the head):

game:GetService("RunService").RenderStepped:connect(function()
    char.Torso.Neck.C0 = (((CFrame.new(0,1.5,0)*(camera.CoordinateFrame-camera.CoordinateFrame.p)):inverse()*(char.Torso.CFrame-char.Torso.CFrame.p)):inverse())
end)