How to detect Cframe moving by a specific amount

[angrybino]

It will stay at 10, what you can do is increase it by the distance travelled:

local startingCamPos = workspace.CurrentCamera.CFrame.Position  -- get the position at starting point

game:GetService("RunService").Heartbeat:Connect(function()
      local distance = (startingCamPos - workspace.CurrentCamera.CFrame.Position).Magnitude

	game.Lighting:WaitForChild("Blur").Size += distance 
end)