Learning About Optics

One of the hard things about machine vision is selecting the correct lens. When possible, you should consider the use of a telecentric lens, which work especially well for small applications typically 2 inches and smaller. For very small Field of View (FOV), consider the use of an Infinistix. These lenses are very small fixed focus length lenses and are great to work with. For larger FOV, I like the telecentric lenses from Melles Griot. As the size and cost of the telecentric lenses rapidly increases with size of the FOV, the vast majority of applications use more of the standard type of video lens. To help you figure out which lens you will want to start with, consider using this optics calculator. All you need to do is fill in the blanks and it will tell you exactly what size of lens you need; I have found that it is very reliable. As this gives odd sizes, you may need to adjust your working distance to get to a "standard" size lens or consider adding extension tubes to a standard lens to make it work for you. Remember: as you add extension tubes it requires more and more light to make the vision system work reliably.