Opticon NFT 1125 User Manual
Page 14
Manual No. 25-NFT1121-01
Series NFT-1121/2135 Mini CCD Fixed Position Scanners
Depth-of-Field
Just as with a camera, the scanner has a depth-of-field. It can read bar codes that are not precisely at
the focal distance - maybe a little closer, or a little farther away. However, if the bar code label is
positioned too far from the focal distance, the scanner may not be able to successfully decode it.
The depth-of-field varies based on the density of the bar code, i.e., the thickness of the bars. High
density bar codes (which have very narrow bars) are readable over a much shorter distance range than
low density bar codes with larger bars.
The following table shows the typical depth-of-field (closest to farthest reading distances) for the NFT-
1125/2135 Series scanners. The actual performance may differ slightly from unit to unit. Also, it is
important to note that this data was measured under ideal conditions using high quality bar code labels.
In a real world environment the conditions will not be as ideal. Therefore, the best practice is to
position the scanner at its focal distance rather than at the extremes of its depth-of-field.
Typical Reading Distance
from Window Depth-of-Field
Readable Bar Code Width (Field-of-View)
The following table shows the field-of-view at various distances from the window. The field-of-view is the
maximum width that the scanner is capable of reading. A bar code label positioned anywhere within this field-
of-view can be decoded. The field-of-view is also a measure of the widest bar code label that can be read.
Remember: the width of a bar code label includes not only the bars and spaces but also the required white
space (quiet zone) on each end.
Good design policy is to position the scanner at its focal distance and at the center of the field-of-view. Do not
position it near the extremes of the reading range.
Page 8
1127
Front View
1126
Side View
2127
Front View
2126
Side View
Bar Code
Density
Min.
Max.
Min.
Max.
Min.
Max.
Min.
Max.
13.0 mil
0.0 in
1.5 in
0.0 in
1.4 in
0.0 in
2.4 in
0.5 in
2.6 in
10.0 mil
0.0 in
1.1 in
0.0 in
1.1 in
0.2 in
1.9 in
0.6 in
2.1 in
7.5 mil
0.0 in
0.9 in
0.0 in
1.0 in
0.4 in
1.7 in
0.7 in
1.9 in
6.0 mil
0.0 in
0.8 in
0.2 in
0.9 in
0.6 in
1.6 in
0.8 in
1.8 in
5.0 mil
0.0 in
0.7 in
0.3 in
0.7 in
1.0 in
1.5 in
0.9 in
1.6 in
Field-of-View
(Maximum Readable Bar Code Width)
Distance
from Window
1127
Front View
2127
Front View
1126
Side View
2126
Side View
0.5 in
2.6 in
2.6 in
2.5 in
2.5 in
1.0 in
2.9 in
3.0 in
2.7 in
3.1 in
1.5 in
3.3 in
3.4 in
3.0 in
3.5 in
2.0 in
3.7 in
3.9 in
3.2 in
3.8 in
2.5 in
4.3 in
4.1 in