Banner PresencePLUS Megapixel C-Mount Lenses User Manual
Printed in USA 08/03 P/N 69950 rev. B
WARNING . . . Not To Be Used for
Personnel Protection
Never use these products as sensing devices for personnel
protection. Doing so could lead to serious injury or death.
These sensors do NOT include the self-checking redundant
circuitry necessary to allow their use in personnel safety
applications. A sensor failure or malfunction can cause either an
energized or de-energized sensor output condition. Consult your
current Banner Safety Products catalog for safety products which
meet OSHA, ANSI and IEC standards for personnel protection.
Lens Selection Guide
Table of Contents
General Lens Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Field of View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Determining Field of View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
FOV Formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Calculated FOV Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Determining Working Distance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Determining Focal Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Focal Length Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Focal Length Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Focal Length and Lens Extension Tables . . . . . . . . . . . . . . . . . . . . . . 6
Focal Length Table, Working Distances in Inches . . . . . . . . . . . . . . . . 6
Lens Extensions Table, Working Distances in Inches . . . . . . . . . . . . . 7
Focal Length Table, Working Distances in Millimeters. . . . . . . . . . . . . 8
Lens Extensions Table, Working Distances in Millimeters . . . . . . . . . . 9
Working Distance vs. FOV Graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Focal Length Formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Lens Options Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Banner Engineering Corp.
www.bannerengineering.com • Tel: 763.544.3164
•
Minneapolis, MN
•
USA
P/N 69950 rev. B i
Lens Selection Guide
ii P/N 69950 rev. B
Banner Engineering Corp.
www.bannerengineering.com • Tel: 763.544.3164
•
Minneapolis, MN
•
USA
Lens Selection Guide
General Lens Considerations
There are many lens options to consider, such as focal length, mounting style, and focus
locking. The two most critical lens considerations are mounting style and focal length. Banner
products use C-Mount lenses only. Before selecting the appropriate focal length, Field of View
(FOV) and working distance must be determined.
Banner offers C-Mount lenses of the following focal lengths (in millimeters): 4, 8, 12, 16, 25,
50, and 75. Other manufacturers’ C-Mount lenses may also be used.
The following sections provide a tour through the process of determining the Field of View,
working distance, and focal length:
Determining Field of View
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 2
Determining Working Distance
Determining Focal Length
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 4
For additional help, support is available from your local Banner representative or a Banner
Application Engineer. Application Engineers are available from 8:00
A.M. to 5:30 P.M. Central
Time, Monday through Friday, excluding holidays.
Field of View
Field of view (FOV) is the area of the inspection captured on the camera’s imager. The size of
the FOV and the size of the camera’s imager directly affect the image resolution (one
determining factor in accuracy). See the illustration below.
NOTE: The PresencePLUS Pro camera imager
size is 640 pixels wide by 480 pixels tall.
Working
Distance
Camera
Lens
480 pixels
(vertical FOV)
640 pixels
(horizontal FOV)
Imager
Banner Engineering Corp.
www.bannerengineering.com • Tel: 763.544.3164
•
Minneapolis, MN
•
USA
Field of View
P/N 69950 rev. B 1
Lens Selection Guide
Determining Field of View
To determine FOV size: Measure the size of the inspection area (inches or millimeters), and
allow extra area to accommodate any anticipated movement of the target object.
To verify that the FOV is sufficient for the required resolution:
1. Estimate the required resolution or minimum detection size; for example, will the inspection
measure to a tolerance of 0.1 mm? 1 inch? 10 feet?
2. Use the FOV Formula below to determine the maximum horizontal and vertical FOV that will
maintain the required resolution.
3. Verify that the calculated FOV is larger than the inspection area.
FOV Formula
Required Resolution x 640 pixels = Maximum Horizontal FOV
Required Resolution x 480 pixels = Maximum Vertical FOV
Calculated FOV Example
Approximate area of inspection is 3.0" by 3.5". Required resolution is 0.01".
For the required resolution, is the area of inspection an acceptable FOV?
Required Resolution x 640 pixels = Maximum Horizontal FOV.
0.01" x 640 = 6.4" Maximum Horizontal FOV.
Required Resolution x 480 pixels = Maximum Vertical FOV.
0.01" x 480 = 4.8" Maximum Vertical FOV.
The Calculated FOV (6.4" x 4.8") is larger than the area of inspection;
therefore, a 3.0" x 3.5" FOV is acceptable.
If the calculated FOV is smaller than the desired area of inspection, options are as follows:
• Use multiple cameras.
• Inspect a smaller portion of the area.
• Reduce the resolution requirement.
Banner Engineering Corp.
www.bannerengineering.com • Tel: 763.544.3164
•
Minneapolis, MN
2 P/N 69950 rev. B
•
USA
Lens Selection Guide
Determining Working Distance
Working distance is the distance between the back of the lens and the target object.
Camera
Working
Distance
Target Object
Some of the key factors that can restrict working distance are as follows:
• The minimum working distance of Banner’s standard lenses is about 2.5 inches. Banner’s
high-performance lenses and most C-Mount lenses have a minimum working distance of 14
inches (spacers can be used to reduce that working distance).
• The lens may need to be close to the target object to avoid light fluctuations.
• There may be physical constraints that limit where the camera can be mounted.
Banner Engineering Corp.
www.bannerengineering.com • Tel: 763.544.3164
•
Minneapolis, MN
•
USA
P/N 69950 rev. B 3P/N 69950 rev. B 3
Lens Selection Guide
Determining Focal Length
Focal length is the distance between the rear nodal point of the lens (the point where the light
rays leave the rear of the lens) and the camera’s imager and is specified in millimeters.
Focal Length
Camera
Model PPCAM
Lens
Imager
-----------------------------------------------------------------------
Focal Length Tools
To choose the best focal length for a specific application, use any of the following tools:
Focal Length and Lens Extension Tables
Working Distance vs. FOV Graphs
Focal Length Formula
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 16
. . . . . . . . . . . . . . . . . . . . . . . . . . page 6
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . page 10
4 P/N 69950 rev. B
Banner Engineering Corp.
www.bannerengineering.com • Tel: 763.544.3164
•
Minneapolis, MN
•
USA
Lens Selection Guide
Focal Length Considerations
If more than one focal length seems appropriate for the application, consider the following:
• Cost: A lens with a shorter focal length is less expensive.
• Depth of focus capability: Depth of focus (focus tolerance) is the area in front of and beyond
the optimal point of focus in which the image quality remains acceptable. A longer focal
length provides less depth of focus; a shorter focal length provides more depth of focus.
• Distortion (see example below): A larger focal length lens provides a less distorted image.
Gauging and the pattern matching tools are sensitive to distortion.
Image of Grid with 25 mm Lens
Banner Engineering Corp.
www.bannerengineering.com • Tel: 763.544.3164
•
Minneapolis, MN
•
USA
Image of Same Grid with 4 mm Lens
P/N 69950 rev. B 5P/N 69950 rev. B 5
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