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Machine Vision Lens FAQ

The questions buyers ask us most, answered with the numbers we actually work to — focal length and sensor matching, resolution, distortion, drawings, lead times, custom design and warranty.

Choosing and matching a lens

How do I choose the focal length for my field of view and working distance?
Focal length = sensor width × working distance ÷ field of view. For example, a 1/2″ sensor (6.4 mm wide) at a 300 mm working distance needs roughly a 19 mm focal length for a 100 mm field of view. Our lens selector runs this calculation and lists the models that meet it.
How do I know whether a lens resolves my camera’s pixels?
Match the lens to the pixel pitch, not the megapixel count. Nyquist frequency = 1 ÷ (2 × pixel pitch): a 3.45 µm pixel needs usable contrast at about 145 lp/mm. Send us your camera model and we will check it against measured MTF at that frequency.
How do I choose the sensor format, and what happens if it does not match?
The lens image circle must cover the sensor diagonal. A lens rated for a larger format also covers smaller sensors — a 1.1″ lens works on 1″, 2/3″ and 1/2″ cameras. If the lens is rated smaller than your sensor you get vignetting, dark or black corners, and the outer field loses resolution. Check the sensor format in your camera datasheet, not the resolution.
When do I need a telecentric lens?
Use one when you measure parts that vary in height, or when perspective error would change the apparent size. A standard lens makes an object look smaller as it moves away; a telecentric lens keeps magnification constant over a defined depth range. For flat parts and simple presence or code checks, a standard fixed-focal lens is usually enough and costs far less.
My line has vibration and dust — what should I look for?
Lock the focus and aperture rings after set-up and keep the mount and fixture rigid. Add a protective window or housing where there is dust or oil mist. For continuous vibration, tell us the amplitude and frequency and we will look at reinforced mechanics and a wider-temperature design.

Optical performance and test data

What is MTF, and are your figures measured or typical?
MTF, the modulation transfer function, is how much contrast a lens preserves at a given detail size, in line pairs per millimetre. Our published figures are measured, not typical: MTF is tested on an optical transfer function instrument covering 0–500 lp/mm for visible and NIR, and 0–60 lp/mm for LWIR, with on-axis accuracy better than ±2%. Distortion is measured to better than 0.25% accuracy. Per-unit signed test reports from our CMA / CNAS accredited optical testing center can ship with production units.
How much distortion is acceptable?
It depends on whether you measure or only detect. For presence checks and code reading, 1–2% TV distortion is usually fine. For dimensional measurement, distortion feeds straight into the result, so use a low-distortion model — many of our FA lenses are specified under 1.5% TV distortion — or a telecentric lens, and correct what is left in software with a calibration target.
Can I get the 3D model and the dimensional drawing?
Yes. Every model page carries a free PDF datasheet with the mechanical outline, flange-back distance and thread sizes, with no form and no sign-up. Full-size PDF, STEP / 3D model and measured MTF and distortion reports are available on request.
Which mounts do you support, and can you change one?
C, CS, F, M42, M58 and M72 as standard. We supply adapters and can also change the mount at the factory. If your camera uses a mount that is not listed here, send us the flange-back distance and thread specification and we will check it.
Do you have near-infrared (NIR) versions?
Standard lenses ship with a visible-light coating. For 850 nm or 940 nm near-infrared work we develop an NIR version as a custom design — the coating, and where needed the optical design, matched to your wavelength band. Development takes about 6 weeks and the minimum order quantity is one piece. Send us your wavelength, illuminator and target resolution and we will confirm what is achievable.

Ordering, delivery and warranty

What is your minimum order quantity?
One piece — for standard lenses and for custom designs alike. There is no minimum order quantity to start working with us.
What are your lead times?
Standard lenses in stock are dispatched within 3 working days. Standard lenses that are not in stock take about 3 weeks. Custom designs take about 6 weeks. We confirm the actual date when you place the order.
Can you design a lens from scratch for my application?
Yes, from 0 to 1. Optical design, mechanical design and metal machining are all in-house, so we can take a specification through to production: focal length, mount, housing, coating and engraving, or a completely new optical design. The minimum order quantity is one piece and typical development is about 6 weeks.
Can you sign an NDA before we share our drawings?
Yes. We sign mutual or one-way NDAs before you share drawings or specifications — for custom projects and for standard-lens enquiries alike. Send us your own NDA template, or ask for ours.
Can I test a sample before placing a volume order?
Samples are sold rather than lent, and are not returnable. Because the minimum order quantity is one piece, you can buy a single lens, test it on your own station, and move to volume once it passes.
What is the warranty?
12 months. Any failure that is not caused by misuse is replaced free of charge.
Are your lenses RoHS and REACH compliant?
Yes. Our lenses are RoHS and REACH compliant, and a certificate of origin can be issued with your shipment. Tell us when you order if you need the documents in a particular format.
Which trade terms do you ship on, and can I use my own forwarder?
Both EXW and FOB are available. Shipment goes by international express (DHL / FedEx) or through a freight forwarder you nominate — the choice is yours for every order. Tell us which you prefer when you order and we will quote accordingly. Certificates of origin and other export documents can be issued with the shipment.
What do you need from me to give a quote?
Four things are usually enough: your camera model, or the sensor format and pixel pitch; the field of view you need; the working distance; and the mount. A drawing or a photo of the part helps. We reply with a selection proposal and test data within one business day.

Still not sure which lens fits?

Send us your camera model, field of view and working distance — we reply with a selection proposal and test data within one business day.

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