How to Choose the Right Machine Vision Lens

a machine vision lens

After hours of research, you’ve finally decided on a machine vision system for your facility. But you still have choices to make. There are a plethora of lens options available. What is the importance of a machine vision lens? And how are you going to pick the right one for your application? Let the experts at Phase 1 help you decide.

How a Machine Vision Lens Works

Like any other camera, the lens is essential to machine vision image capture. Light enters the lens and is sent to the camera sensor for processing. For an automated system to successfully process an image, the image must be of sufficient quality. The lens you pick will need to capture a clear image at a high enough resolution to yield accurate results. Contrast, depth-of-field, the field of view, working distance, mounting, and cost are all critical to the lens you select.

Sure, it’s a no-brainer that the lens you choose needs to capture a clear image. But it also needs to do so at a speed to keep up with your automated processes. And an accurate, reliable lens will reproduce similar results every time for fast analysis. To stand up to harsh environments, you may need a lens that’s outfitted with a metal housing or a robust focusing mechanism. Replacing faulty lenses can lead to downtime costs that far exceed their price tag.

Pick the Right Machine Vision Lens

1. Decide on a Lens Type. If your sensor has a resolution of a megapixel or less, a standard resolution lens will likely work for you. These lenses can focus on infinity and are designed with minimal distortion and vignetting. If you’re in need of a smaller pixel size, high-resolution lenses can deliver precise measurements.

2. Select an Appropriate Focal Length. Deciding on the correct focal length will require measuring the distance between the camera and the object you are looking at. Also part of the selection process is reviewing the object you are examining. If this is an inspection application, consideration will have to be given to whether you are looking at the entire object or just the part you are inspecting. Most machine vision applications can be solved by using standard C mount fixed lenses between 8 to 75 mm. Consideration must also be given to the format size of the sensor in the camera. Large format size sensors may require an F mount or M42 mount in order to accommodate the physical size of the sensor, and not cut off any pixels on the corners of the sensor.  Telecentric lenses are especially well-suited to metrology applications. They can Magnify an image without perspective distortion but often become cost-prohibitive when a large field of view is required.

3. Choose Application-Specific Features. Most lenses are available with a number of configurable options. Picking the right balance between precision, speed, and quality, and then matching them to your camera's specification will always give you the best results. Different motors can be used to control lens focusing and pick the right balance between precision, speed, and quality. From iris control to light filters to lens mounting kits, you can pick a lens that is perfect for your application. In addition to conventional lenses, electrically tunable liquid lenses allow for cutting-edge shutter speed.

Not sure what’s best for your automation system? Contact the experts at Phase 1 to get the right machine vision lens for your application.