Lens selection

Usually surveillance cameras use wide lenses of 2.5mm and up.

The most popular is the 3.6mm lens which would give you about 70 degrees  field of view (FOV) horizontally and 57 degrees vertically

A 6mm lens would give you about 48 degrees FOV horizontally and 37 degrees FOV vertically (for 1/3” CCD sensor)

More mm means smaller FOV

Telephoto lenses are 20mm and up

Many of our cameras are varifocal so you can adjust the focal length to suit,
usually the varifocal will be in the range of 2.8mm-10mm.

If you are in a changing low light environment consider an an auto iris lens.