This lens calculator displays the viewing angle and the focal distance for CCTV lenses. The lens calculator is a basic guide and can be used when using any CCD sizes, such as 1/4 inch, 1/3 inch which are the typical CCD sizes used in the CCTV industry. The chart below also shows the distance you can view small objects from such as car number plates with varying lens sizes.
Another thing to keep in mind is that when the viewing distance increases your angle of view decreases. Therefore if you selected a 3.6mm lens over a 16mm lens you may not be able to view objects that are far away but you would have a wider field of view.
If you are unsure as to what size lens best suits your application we will normally recommend a vari-focal lens which can be adjusted within the range of the lens to give the best viewing angle and distance. A vari-focal lens can be adjusted by the engineer during installation to capture the very best surveillance images.
The above information provides you with a good guide for calculating what size lens you will need, however if you want to do an exact calcualtion you can use the following formula.
f = c x d ÷ w
f = lens size needed (mm)
c = chip width (mm) 1/3" CCD = 4.8mm, 1/4" CCD = 3.2mm
d = distance of object from camera (m)
w = width of view required (m)