Use a joystick.
It may only be January, but I'd like to nominate this comment as the most useless post for the entirety of 2016.
Always use the right tool for the job, which in this case would be something with a linear response.
The keyboard is the right tool,
The OP isn't happy with the digital response you get from the keyboard. He'll be a lot happier with a joystick. Trust me, I actually own a joystick.
So do I. However, my stick doesn't stop me from understanding how to set up the game.
How do you damp the digital response then?
It's still way too sensitive IMO, even with an analogue joystick.
My turret is really jumpy - I since found out its afraid of the dark...
Indeed
Well my mouse pointer jumps every now and then making it very frustrating to try and use, so I have my X52Pro set for operating the turret, up and down is just fine, but left and right the aim shoots past the target every time