How do I set up a camera and lens for use in Low Light conditions and or with Infra Red Lighting?

How do I set up a camera and lens for use in Low Light conditions and or with Infra Red Lighting? 

  The addition of the following: When setting the back focus of a Colour camera for low light conditions you should place an ND1 (Neutral Density) filter in front of the lens. When setting the back focus of a Mono camera for low light conditions you should place an ND3 (Neutral Density) filter in front of the lens. When setting the back focus of a Mono camera fitted with I/R lighting for low light conditions you should place an IRP (Infra- Red Pass) filter in front of the lens. Should you not have any of the above filters you may have to attend site during the hours of darkness.            

The addition of the following: When setting the back focus of a Colour camera for low light conditions you should place an ND1 (Neutral Density) filter in front of the lens. When setting the back focus of a Mono camera for low light conditions you should place an ND3 (Neutral Density) filter in front of the lens. When setting the back focus of a Mono camera fitted with I/R lighting for low light conditions you should place an IRP (Infra- Red Pass) filter in front of the lens. Should you not have any of the above filters you may have to attend site during the hours of darkness.