Object-size lens & exposure calculator

Camera / machine-vision setup: set working distance and object size, compare lenses for FOV and DOF, then get a camera shutter for line speed.

Inputs

FOV

Working distance

cm from camera to object

Object width

Object height

cm (0 = square = width)

Active sensor area

Optical class · active aspect · approximate mm

Exposure

Output resolution

Output / ROI sampling · active area controls FOV

Line speed

at the object plane

Speed unit

for shutter result

More options

FOV · Coverage fit

Buffer on object size — affects cover/tight fit and the dashed yellow box.

Safety margin

% buffer beyond object size

FOV · Custom active area

Use the camera datasheet's active dimensions for the most accurate FOV.

Active width

mm active area

Active height

Exposure · Custom output

Used when Output resolution is Custom. This changes output/ROI sampling, not the physical active area.

Output width

px · 0 omits pixel calculations

Output height

px · 0 omits vertical scale

Exposure · Motion freeze

How many pixels of smear are allowed when recommending max exposure.

Blur budget

px of smear allowed

FOV · Depth of field

Prefer the aperture slider under the DOF graph. These fields sync with it.

Aperture (f-number)

synced with DOF slider

Circle of confusion

How to use & terms

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

Set working distance (cm) and object width/height.
Choose a sensor format, then click lenses in Lens result until cyan FOV covers the yellow object.
Check FOV result, the side/isometric graphs, and the bar chart of all lenses.
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).
Use the aperture slider under Depth of field for a rough sharp range (focused on the object).
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.

Not a substitute for manufacturer optics data. Aperture / DOF ignores diffraction and lens design specifics.

Lens result

Green underline = covers object + margin; amber = tight; dim = does not cover. Gold “best” = suggested (~25% spare). Grey “widest” = nothing covers — least-bad option only.

Custom focal length

Focal length

mm — adds under the matching group

Minimum working distance, distortion, and mount coverage vary by lens — confirm on the manufacturer datasheet before you buy or mount.

FOV result

Shutter result

Side view

Width cross-section only: FOV width at working distance vs object width (+ margin). Height is checked in the recommendation and lens underlines; see also the isometric view.

Isometric field of view

3D-style view of the imaging volume — the cyan rectangle is the FOV at the object plane; yellow is the object size.

Depth of field

Approximate range that stays sharp when focused on the object — not a datasheet. Adjust aperture with the slider.

Aperture f/4

Show calculations

Formulas with your current numbers plugged in.

Thin-lens / CoC approximation. Confirm critical setups with your datasheet. Diffraction is not modeled.

Compare all lenses

Bars and yellow marker use FOV width vs object width + margin only. Height is checked in the recommendation and lens underlines — a bar past the marker can still fail on height.