i have a camera with 1/3 " format. I have a cctv lens in front of it with a focal length of 50mm. In order to improve my FOV i intend to use a cctv lens of a smaller focal length, and the vendor is providing me a smaller focal length for a 2/3 " format. i want to know if a cctv of say 25mm focal length, 2/3" format would work equally for a 1/3" format? I also wish to know the relation that exists b/w the diagonal length of the image pick up device and the terminology that is used to represent the size of the image pick up device i.e the format.