Detail Lens Chart - The installer/designer can reference a detail lens chart to determine the exact field of view based on lens focal length and distance to the target.

The chart below is for 1/3-inch format cameras.

For example, with a 1/3-inch format camera viewing a target area 10 feet away will provide the following target sizes:

2.8mm = 12.9 feet X 17.1 feet
4.0mm = 9.0 feet X 12.0 feet
6.0mm = 6.0 feet X 8.0 feet
8.0mm = 4.5 feet X 6.0 feet
12.0mm = 3.0 feet X 4.0 feet

The chart can also be used in reverse. By knowing the object distance and the required target area, you can determine what lens is required.

For example, using the chart for a 1/3-inch format camera viewing an object distance of 50 feet and a target area of 15 feet by 20 feet:

Scan down the "50 feet" column to the stated target size; scan left to see that a 12mm lens is required for that application.