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October 2023
Choosing the Right Machine Vision Lens
Choosing the right machine vision lens can be overwhelming. However, with a few key considerations, you can make an informed decision. Here are some tips to help you choose the best machine vision lens.
Fixed, Varifocal, or Zoom: Fixed lenses are a good option if you have a consistent working distance and require sharp, high-quality images. On the other hand, varifocal lenses are better suited to situations where the subject is in motion and requires refocusing. Finally, zoom lenses are the most versatile of the three and can adapt to distant subjects by changing the focal length.
Focal Length and Focus: The focal length determines the field of view (FOV) and the magnification of the image. A longer focal length will provide a narrower FOV. A shorter focal length lens will result in a broader FOV. Additionally, the focal length will also determine the magnification of the image, with longer focal lengths resulting in greater magnification.
Aperture and Lighting: It's important to understand the relationship between aperture and lighting to achieve the desired depth of field.
Resolution and Accuracy: For maximum accuracy, find a lens with the best resolution for the subject or operation, considering factors such as image clarity, application, options, and cost-benefits.
Working Distance: When selecting the correct lens, designers calculate the needed working distance using three factors: focal length, the length of the inspected object, and sensor size. The required working distance may also be calculated using the object size.1
Sensor Compatibility: Different sensors need different lenses. Smaller pixel sensors need higher resolution lenses for better image quality. A larger sensor requires a larger lens to cover the same field of view.
Camera, Mount, and Location: Ensuring the lens is compatible with the camera's sensor type and mount is crucial. You should also take the camera's location into consideration. If the camera is not easily accessible, it is recommended to use a lens with remote focus, iris, and zoom control, such as our LensConnect Series. These lenses come with power and control through USB, allowing you to remotely adjust the focus, zoom (on varifocal lenses), or iris.
Selecting the right machine vision lens is vital to ensure optimal camera or system performance and image quality. Information flows from the lens first. Before choosing, determine the application, location, and the subject being observed or inspected. Factors such as the camera, resolution, focal length, working distance, and aperture will guide you to choose the best lens for your needs.
References
2. https://www.automate.org/blogs/selecting-the-correct-machine-vision-lens-for-your-application
3. https://computar.com/resources/files_v2/1817/Computar_Industrial_Imaging_Lens_Catalog%2002.03.20
