Lens selection for machine vision

Whenever I talk with manufacturing people – those at the sharp end who actually engineer the activity of making things – about machine vision they tell me that one of the most baffling areas is that of lens selection. Unless they happen to be enthusiastic amateur photographers, all the talk of focal length and f-stops might as well be Greek.

This is why I am return to my familiar theme of how to pick a lens. Today I want to refer you to an excellent paper in the Point Grey Knowledge Base titled, “Selecting a Lens for your Camera.”

This does covers such topics as lens mount formats (C, CS and M12,) what focal length means and how it relates to sensor size, and the importance of pixel size in spatial resolution. These are all important points to be aware of, but unfortunately the article doesn’t actually help you to select a lens.

For that I would like to refer you once more to the excellent MachVis lens selection program, downloadable at no charge from Linos. It’s very easy to use, providing you understand key terms such as sensor format, so read the Point Grey paper then play with the software to learn how to use it.

I can’t guarantee that all your lens problems will be resolved, (groan) but these two tips should help give a clear view of what you need to do.