Low Mag Video Lenses
76
h t t p : / / m a c h i n e v i s i o n . n a v i t a r . c o m
•
e m a i l : i n f o @ n a v i t a r . c o m
Image Size
A lens produces images in the form
of a circle, called the image circle. In
a video camera, the imaging element
has a rectangular sensor area (the
image size) that detects the image
produced within the image circle.
The ratio of the length of the horizon-
tal to vertical sides of a video image
is called the aspect ratio, which is nor-
mally 4:3 (H:V) for a standard video
camera.
Relationship Between Angle of
View and Image Sensor Size
An important factor to remember is
that cameras with different image
sensor chip sizes (such as 1/4”, 1/3”,
1/2”, 2/3” and 1”), using the same
focal length lens, will each yield a dif-
ferent field of view.
Lenses designed for a larger image
sensor device will work on a new,
smaller size camera. However, if a
lens designed for a smaller format im-
age sensor device (i.e. 1/3”) is placed
on a larger one (i.e. 2/3”), the image
on the monitor will have dark corners.
Image sensor sizes are in a ratio of
1:0.69:0.5:0.38:0.25. This means that
a 1/2” format is 50% of a 1” format,
a 1/2” format is 75% of a 2/3” format
and a 1/3” format is 75% of a 1/2”
format.
Minimum Object Distance
Minimum object distance (M.O.D.)
indicates how close the lens can be
placed to the object for shooting. It is
measured from the vertex of the front
glass of the lens.
Image Size Chart
Camera to Monitor Magnification
Optical Characteristics
of Video Lenses
Image Sensor Size (units in mm)
Image Size
Image
Sensor
Image
Circle
Horizontal
Vertical
1/4”
Ø4.0 mm
3.2 mm
2.4 mm
1/3”
Ø6.0 mm
4.8 mm
3.6 mm
1/2”
Ø8.0 mm
6.4 mm
4.8 mm
2/3”
Ø11.0 mm
8.8 mm
6.6 mm
1”
Ø16.0 mm
12.8 mm
9.6 mm
Camera
Format
Monitor Size (diagonal)
9”
14”
15”
18”
20”
27”
1/4”
57.2X
88.9X
95.3X
114.3X
127X
171.5X
1/3”
38.1X
59.2X
63.5X
76.2X
84.6X
114.1X
1/2”
28.6X
44.5X
47.6X
57.2X
63.5X
85.7X
2/3”
20.8X
32.3X
34.6X
41.6X
46.2X
62.3X
1”
14.3X
22.2X
23.8X
28.6X
31.8X
42.9X
