Banner PresencePLUS Megapixel C-Mount Lenses - Manual (Page 8)

Lens Selection Guide
Banner Engineering Corp. • Minneapolis, MN • USA
www.bannerengineering.com • Tel: 763.544.3164
P/N 69950 rev. B
5
P/N 69950 rev. B
5
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 Image of Same Grid with 4 mm Lens