Object-size lens & exposure calculator

What this page does

This is a lens and exposure planner for machine vision and camera setup. You enter how far the camera sits from the object and how large that object is; the tool shows which focal lengths cover it (Lens result / FOV result), an approximate depth-of-field band, and a camera shutter for line speed (Exposure result / Shutter result).

Use it to pick a lens and shutter before buying or mounting hardware — not as a substitute for the camera/lens datasheet on critical jobs.

Quick start

1. Set working distance (cm) and object width/height.
2. Choose a sensor format, then click lenses in Lens result until cyan FOV covers the yellow object.
3. Check FOV result, the side/isometric graphs, and the bar chart of all lenses.
4. Under Inputs Exposure, set output resolution (default 1920×1080) and line speed — read Exposure result and Shutter result for the closest camera step (e.g. 1/500).
5. Use the aperture slider under Depth of field for a rough sharp range (focused on the object).
6. Open More options for margin, blur budget, and CoC. Add a custom focal length in Lens result. Tap or hover ? (and stats) for short tips.

Graph legend

• Cyan — FOV (triangle / frustum / rectangle).
• Solid yellow — object size to cover.
• Dashed yellow — object + safety margin.
• Green band — approximate sharp range (DOF), focused at WD.

Terms

• FOV / HFOV / VFOV Field of view as size at the object plane, or as horizontal/vertical angles. Shorter focal length → wider FOV.
• Working distance (WD) Camera → object in cm. Assumed focus distance for the DOF graph.
• Object / safety margin Size of the part or area to cover, plus optional % buffer. Height 0 means a square (same as width).
• Active sensor area / output resolution Active sensor width and height drive FOV. Output resolution (default 1920×1080) drives mm/px, object → px, and the exposure ceiling. A camera may offer several output aspect ratios by cropping or scaling one sensor; use matching active-area dimensions for precision.
• Sensor scale Sensor size ÷ FOV size — how large the scene is on the chip compared with real life (not phone zoom). Example: at 0.025×, a 1 mm scratch is only 0.025 mm on the sensor and may be hard to resolve unless pixels are fine enough.
• Aperture / DOF / CoC f-number and circle of confusion set how deep the sharp zone is. Approximate thin-lens model only — check min WD and datasheet for real lenses.
• Covers / tight / does not cover FOV must meet object × (1 + margin) on both width and height. Tight means it covers but with less than ~8% spare (spare < 1.08×). Covers means at least that spare. Green / amber / red on the recommendation and lens underlines.
• Suggested / best / widest Among lenses that cover, the gold best badge picks the one closest to ~25% spare FOV (1.25×); tight fits are slightly penalized. If nothing covers, a grey widest badge marks the shortest focal length (largest FOV) — not a good fit, only the least-bad option.
• Exposure result Max shutter ≈ (blur budget × mm/px) ÷ line speed. Shows µs and the nearest common camera steps (1/200, 1/360, …). Prefer a step at or under the max so smear stays within budget. This is a motion ceiling — raise light/gain if the image is too dark.