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Lens Focal Length Calculator
Calculate the approximate lens focal length required for a machine vision camera from target field of view, sensor size, and working distance. It also recommends the closest common lens focal length for first-pass selection.
Input Parameters
Results
Use these results as engineering selection values, then verify with actual lens, camera, PCB, or light-source data as appropriate.
Equations Used
Required focal length:
F = Working Distance / (FOV / Sensor Size + 1)
Covering both width and height:
Use the smaller calculated focal length when the selected lens must cover both requested width and height.
Nearest standard lens:
The calculator compares the required value with common C-mount focal lengths such as 6 mm, 8 mm, 12 mm, 16 mm, 25 mm, 35 mm, and 50 mm.
Frequently Asked Questions (FAQ)
Q1: What does this lens focal length calculator do?
It estimates the focal length needed to capture a required field of view at a given working distance.
Q2: Why does it calculate width and height separately?
A camera sensor and target area both have aspect ratios. The chosen lens must cover the limiting dimension without cropping the target.
Q3: Should I choose the exact calculated focal length?
Usually no. Select the nearest available lens, then check if its actual FOV still covers the target with margin.
Q4: Does this account for lens distortion?
No. Wide-angle and low-cost lenses may have distortion that changes usable FOV and measurement accuracy.
Q5: What else should engineers check?
Check sensor format, mount type, image circle, aperture, working distance, depth of field, distortion, and lens resolution.
