HIKROBOT Lens Selection and Field of View (FOV) Calculator
Select your camera, enter the field of view and working distance, and instantly see the required focal length, the resolution per pixel and the HIKROBOT lenses that fit your camera.
How is it calculated?
The calculator uses the thin-lens approximation that is commonly used for pre-selection in machine vision.
Sensor size
Sensor width = horizontal pixel count × pixel size. For example, 2448 pixels × 3.45 µm = 8.45 mm.
Magnification
Magnification = sensor width ÷ field of view width. The smaller ratio is used so that both the width and the height of the field of view fit on the sensor.
Focal length and working distance
Focal length ≈ working distance × magnification ÷ (1 + magnification). Conversely, the working distance required with a given lens ≈ focal length × (1 + magnification) ÷ magnification.
Resolution per pixel
Area per pixel = field of view width ÷ horizontal pixel count. The smallest detail to be detected should cover no fewer than a few pixels in the image.
Lens compatibility
The image circle of the lens must not be smaller than the sensor diagonal, and the lens mount must match the camera. If the lens resolution (MP) is lower than the camera’s, image sharpness is limited. See HIKROBOT lenses for all lenses, area scan cameras for cameras and HIKROBOT machine vision for general selection.
To calculate the exposure time and frame rate for moving parts, use the line speed, exposure time and frame rate calculator.
Frequently asked questions
How do I calculate the focal length of a machine vision lens?
The calculation uses the thin-lens approximation. First find the sensor width: horizontal pixel count × pixel size. Magnification = sensor width ÷ field of view width. Focal length ≈ working distance × magnification ÷ (1 + magnification). The result is for pre-selection; at short distances, check the lens minimum object distance (MOD) on the product page.
How do I use the lens selection and field of view calculator?
Select one of the cameras on our site or enter the resolution, pixel size and lens mount manually. Then enter the two values you know: the tool calculates focal length from field of view and distance, field of view from focal length and distance, or distance from field of view and focal length. It lists the HIKROBOT lenses that fit your camera, closest to the required focal length first.
What is resolution per pixel, and how many pixels should the smallest detail cover?
Area per pixel = field of view width ÷ horizontal pixel count. It shows how much of the part one pixel represents. For reliable detection, the smallest detail should usually cover at least 3–4 pixels. If it covers fewer, consider a higher-resolution camera or a narrower field of view.
How do I know if a lens is compatible with my camera?
The lens mount must match the camera, and the image circle must not be smaller than the sensor diagonal. If the lens resolution (MP) is lower than the camera resolution, image sharpness is limited. Applications where perspective error matters, such as dimensional measurement, require a telecentric lens. FST can help you finalise the camera, lens and lighting combination for your application.