190
N. Wiget Lane, Suite 202
Walnut Creek, CA 94598
Phone:
(925) 934-CCTV (2288)
Toll Free: (877) 474-CCTV (2288)
Fax: (925) 943-CCTV (2288)
E-mail: info@psscctv.com
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cameras lenses
The advantage to a c-mount camera is that the
lens can be changed. If you need to see further
than 35 or 40 ft then you'll need a c-mount camera
with a special lens. C-Mount lenses are available
from 4mm to 50mm. A 4mm lens provides facial
detail and a 70 degree angle of view focused
up to about 35 ft. An example of where you might
use a fixed 4mm lens is in a small office, or
at home to focus on your driveway.
A higher millimeter lens will provide further
distance, but narrows the field of view. So,
a 16mm lens would provide about a 15 to 20 degree
angle of view at a focus distance of about 35
ft (or a 70 degree angle of view at about 140
feet). In general, a 8mm lens is like a 4mm lens
zoomed in 2 times. Similarily, a 16mm lens is
like the 4mm lens zoomed in 4 times.
Many times, the best option is to use a varifocal
lens. This will allow you to vary the focus from
5 to 50mm. So when you install the camera you
can fine tune the focal distance and angle of
view. An example of where you might use a varifocal
lens is outside (or inside) a large commercial
building where you need more distance than 35
ft. and the varifocal lens will allow you to
adjust the focal distance to your preference.
If you want to use cmount cameras outside, you
must put them in an outdoor camera housing.
CCTV lenses are available
in two different lens mounts. "C-mount" lenses have
a flange back distance of 17.5mm; "CS-mount" lenses
have a flange back distance of 12.5mm. The flange
back distance is the distance from the flange
of the lens (beginning of the lens mount) to
the focal plane. All of the C-Mount cameras we
sell can be adjusted for installation of a CS-Mount
lens as well as a C-Mount lens.
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cameras lensest. |
