Imaging Lenses
Where to Start?
How to Choose an Imaging Lens
Lens Selection, Small Sensors Lens Selection, Medium Format Sensors
500
1595
742.5
875
0 100 200 300 400 500 600 700 800 900 1000
312 +44 (0) 1904 788600 | Edmund Optics® N NEW PRODUCT NEW LOW PRICE
testing & detection targets illumination cameras imimaaggiinngg lleennsseess microscopy lasers optomechanics optics
TECHNICAL NOTE
Imaging Filters/Accessories ...... 145-149, 366-371
Fixed Focal Length Lenses ...................... 314-330
- Light Weight, Low Profi le Designs
- Minimum Working Distance with No Maximum
- Single Angular Field of View
Large Format Lenses ............................... 331-335
UV, IR, SWIR Lenses ................................. 336-337
M12/S-Mount Lenses ............................... 338-341
- Wide Variety of Applications
- Compact Design for Small Format Cameras
Telecentric Lenses .................................... 342-350
- No Parallax Error
- Superior Image Quality
- Ideal for Metrology and Gauging
Variable Magnifi cation Lenses ........................ 351
Zoom Lenses ............................................ 352-359
- Flexible Focal Length and Angular Field of View
Specialty Lenses ...................................... 360-365
IMAGING SYSTEM BASICS
There are a few basic parameters that should be understood about every imaging system. Knowing
these parameters will help in selecting the ideal lens and camera combination.
FUNDAMENTAL PARAMETERS:
Field of View (FOV): The viewable
area of the object under inspection. This
is the portion of the object that fi lls the
camera’s sensor.
Working Distance (WD): The distance
from the front of the lens to the object
under inspection.
Resolution: The minimum feature size
of the object that can be distinguished by
the imaging system.
Depth of Field (DOF): The maximum
object depth that can be maintained entirely
in acceptable focus. DOF is also the
amount of object movement (in and out
of best focus) allowable while maintaining
focus.
DOF
FOV
WD
Sensor Size
Resolution
Sensor
Camera
Working Distance (mm)
400
300
200
100
0
1276
957
638
319
0
Horizontal FOV (mm, " Sensor)
Horizontal FOV (mm, 1" Sensor)
594
445.5
297
148.5
0
Horizontal FOV (mm, ." Sensor)
700
525
350
175
0
Horizontal FOV (mm, " Sensor)
0 100 200 300 400 500 600 700 800 900 1000
Working Distance (mm)
f=3.5mm
f=16mm
f=4.5mm
f=25mm
f=6mm
f=35mm
f=8.5mm
f=50mm
f=12mm
f=100mm
f=6mm
f=35mm
f=8.5mm
f=50mm
f=12mm
f=100mm
f=16mm f=25mm
The fi gures below show Horizontal Field of View (FOV) vs. Working Distance
(WD) for four diff erent sensor sizes: (⅓ ", 1⁄1,8", ⅔ ", and 1"). By fi rst selecting
a sensor size and then fi nding the Horizontal FOV and WD required
on the plot, the appropriate focal length of the imaging lens that will work for
your application can be determined.
Important Considerations for Choosing an Imaging Lens:
• Longer focal length lenses have longer minimum working distances, which
is a consequence of their optical designs. Minimum working distance can
be shortened by adding spacers between the lens and camera, but image
quality will eventually suff er.
• Larger sensors provide larger FOVs with the same focal length lens. For
example, at a working distance of 350 mm, a 12 mm lens on a ⅔ " sensor
will have an FOV of about 370 mm, but on a 1" sensor at the same working
distance, the fi eld of view is approximately 530 mm - an increase of 43%.
• There are gaps in the plots, indicative that a standard off -the-shelf fi xed
focal length lens does not exist. For example, it is impossible to achieve
a 525 mm fi eld of view at a 600 mm working distance with a ⅔ " sensor
with available focal lengths. The closest lens that exists is an 8,5 mm focal
length, which would need to be used at a working distance of about
510 mm to achieve that fi eld of view.
*These plots are based on TECHSPEC® C Series Fixed Focal Length Lenses. However, these plots can be applied to any lens and are not limited to only the TECHSPEC® C Series Lenses.