29
Camera-to-object distance x 4.4
Object width
4. Selecting the correct zoom factor
The quality of the video picture depends very much on the zoom factor selected. When selecting a
zoom factor, note these installation tips:
Perception
Large area covered (zoomed out), so no
detailed recognition possible. A 2m tall
person takes up about 5% of the screen
height. The monitored area has a size of
about 50m x 40m (WxH). A camera at 30
meters requires a lens with a focus of
f=2.8mm.
Detection
Large area covered (zoomed out), so little
detailed recognition possible. Use of video-
sensors possible. A 2m tall person takes up
about 10% of the screen height. The monitored
area has a size of about 25m x 20m (WxH). A
camera at 30 meters requires a lens with a
focus of f=6mm.
Recognition
Small area covered (zoomed in); details can
be recognised. A known person is
recognisable. A 2m tall person takes up
about 50% of the screen height. The
monitored area has a size of about 5m x 4m
(WxH). A camera at 30 meters requires a
lens with a focus of f=28mm.
Identification
Small area covered (zoomed in); details can be
recognised very clearly. A 2m tall person takes
up about 120% of the screen height. The
monitored area has a size of about 2.5m x 2m
(WxH). A camera at 30 meters requires a lens
with a focus of f=60mm.
Use the following formula for calculating the lens focus:
f (focus) =
