Simple CCTV Lens Angle Calculator
In many cases, determining the right lens for your installation can make the difference between success and disappointment when capturing events on video. Keep in mind that there is always a compromise between the amount of activity (width of field) versus the amount of detail ("zoom" factor). In general, the "wider" the angle of view, the less detailed the image will be. On the other hand, a very sharp image can be gained by narrowing the field of view, but this will be at the expense of getting a wider viewable area.
Use this calculator to determine the right lens angle for your specific camera position, then choose a fixed or varifocal lens and/or camera that meets this requirement.