Focal Length - Iqinvision IQeye User Manual

Ideally, you will choose a lens that has the exact format of your imaging chip.
2/3" CS-mount lens
1/3" CS-mount lens
1/4" CS-mount lens

9.2.2 Focal Length

The focal length of a lens is the distance, in millimeters, from the optical center of the lens to the
camera's imaging chip. This distance determines the amount that objects within a camera's
image are magnified.
Lenses with high focal lengths produce larger, more magnified objects. Such lenses are called
telephoto lenses. Conversely, smaller focal length or wide-angle lenses show objects at less
magnification than they appear to the human eye from the same distance. The "normal" value
for a given focal length is the distance at which the camera's image is the same as the eye's.
To calculate the level of magnification for a particular focal length, divide the focal length by
the normal value. For example, an object will appear 3 times as large when a 24mm lens is
placed on a camera that has a normal value of 8 mm.
telephoto lens
(24mm 3x magnification )
focal length
magnification =
normal
IQeye 1/3" CMOS imager
IQeye 1/3" CMOS imager
IQeye 1/3" CMOS imager
normal lens
(8mm unmagnified )
wide angle lens
(4mm 50% of normal )
lenses
71