The purpose of the lens is to manage and direct light. To properly select a lens for your vision application, it is important to know the focal length, resolution, field of view, and working distance. Each lens has an optimal focus area, so trying to adjust any of these aspects after project completion can affect the focus and reliability of the system.
When working with lenses that are less than 9mm, watch for barrel distortion. Barrel Distortion makes the object look like it was wrapped around a sphere. This means the edges of the field are not as magnified or clear.
For short focal length lenses (9 mm or less) you will want to stay inside the center portion of the lens’ view and avoid the distorted perimeter area of the lens’ field of view.
Other things to watch for when selecting a lens:
- Lens selection should be based on the size of the cameras imager (Format)
- Typical Machine Vision lenses are either 1/3”, 1/2”, or 2/3” format
- Select a lens with a locking focus and aperture (usually a thumbscrew is used to do this)
- Be sure the lens has threads to accept the filter of your choice
If you would like to learn more about Basic Machine Vision Hardware, see our other vision series posts or contact our sales group.