Machine Vision
Lens Calculator
Find the focal length needed to fit your object in frame using sensor size, object dimensions, and working distance.
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Continue to Camera FOV Calculator — 25 mm lens · 400 mm WD · 2448x2048 preset
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How it works: Thin-lens model f = sensor × WD / object. When width and height disagree, the shorter focal length is recommended so both axes fit without cropping.
Learn about this tool
What it is, when to use it, formulas, and common questions
What is this?
Finds the focal length needed to fit your object in frame given sensor format, object size, and working distance.
When do engineers use it?
Use early in vision system design when you know what must fit in the image but haven't picked a lens yet.
Formula
f ≈ (sensor width × WD) ÷ object width
Example
To fit a 200 mm wide conveyor at 500 mm WD on a 2/3" sensor, you typically need ~16–25 mm focal length.
FAQ
- Should I size from width or height?
- Compute both, then use the shorter focal length so neither axis is cropped. A longer lens increases magnification but narrows FOV and will clip the other dimension.
- Does this match the lens datasheet FOV?
- It uses a thin-lens model. Real C-mount lenses have distortion and slightly different effective FOV. Shortlist a focal length here, then confirm against the manufacturer table for your sensor format.
- What working distance should I enter?
- Enter the planned mount-to-object distance, not the catalog minimum WD. If the bracket height is not fixed yet, try a few WD values and see how focal length trades off.
- What should I do after I get a focal length?
- Open Camera FOV Calculator to confirm mm/px, then Depth of Field if part height varies, then Camera Placement Planner for the physical mount.