Chapter 23 - Mirrors and Lenses - Learning Path Questions and Exercises - Exercises - Page 806: 1

5 m

The camera should be focused to 5 m because the virtual image will be 2.5 m behind the mirror while the object is 2.5 m away in front of the mirror. This is because $d_{o}=d_{i}$ at a plane mirror. Adding these values together results in the image having a total distance of 5 m from the camera.