Hello, I have a special little S16mm PL mount camera and I need to adjust the FFD. The FFD is a little too long not allowing me to hit infinity nor have my marks line up on wider lenses.  I will need to either replace the mount or machine some metal off to make it work properly. I'm trying to calculate how much I would need to reduce the mount by to have it properly spec'd. Can anyone help me with the math required to determine the difference in FFD? I pointed the camera at a focus chart an