Spacer Rings, Varifocal or Custom Focal Length: Choosing and Documenting an Exact FOV
Answer the field of view question with the error budget, not with whichever option is easiest to buy. If a catalog lens already produces...
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The RFQ asked for custom glass. The drawing was a 25 mm C-mount, 2/3″, distortion below 0.05%, 200 mm working distance. That cell already lives in the FA catalog. Custom optics vs catalog lenses is not a prestige choice. It is whether the published prescription already closes the station. Paying NRE for a catalog job burns 60 working days you did not need.
Key Takeaways
- Catalog first when format, mount, FOV and distortion already match a published cell.
- Custom when the drawing or sample is not in the catalog: odd image circle, DLP/UV, spectrometer, reverse engineering.
- Prototype to mass production: 60 working days. Repeats: 30 days. RFQ first-pass: 48 hours.
- Tooling stored free for 5 years. Payment 50% advance + 50% before shipment. NDA before drawings move.
- ISO 9001 certified 2024. Company registered 2019. Do not call the company 26 years old.
- Do not pay NRE so the PO can say OEM.
The RFQ That Did Not Need NRE
Buyer-advocate rule: open the catalog before you open a tooling quote. FA3505W, FA5005W, FA2520W, FA3520W, FA5020W, FA7520W and the LMHS-MH series already cover a lot of 2/3″ to 1.1″ C-mount work with distortion held below 0.05%. If the five inputs in the machine vision lens selection guide land on one of those cells, stop. Custom is for the leftover.
Machine vision stations fail more often on a wrong catalog pick than on missing NRE. A 16K line on a 2/3″ FA barrel is a catalog error, not a reason to skip the catalog. Match the family first.
If a published cell already hits format, mount and distortion, custom is a delay, not an upgrade.
Custom vs Catalog Compared
| Parameter | Catalog | Custom |
|---|---|---|
| Start from | Published cell | Drawing or sample |
| Lead time | Stock / short run | 60 working days to MP |
| Repeats | Catalog cycle | 30 days |
| Tooling | None extra | Stored free 5 years |
| Payment | Quoted per lot | 50% + 50% before ship |
Verdict — catalog: Default. FA, M12, telecentric, line-scan, liquid, endoscope, wide-angle, thermal. If it fits, buy it.
Verdict — custom: When the circle, waveband, or envelope is not in the book. Reverse engineering, DLP/UV micro-projection, UV exposure objectives, spectrometer modules. That is the custom optics path, not a sticker on an FA2505A.
The Clock: 60, 30, 48 and 5 Years
Write the dates as they stand. Prototype to mass production is 60 working days. That is the standard written commitment, not a slogan. Repeat orders are 30 days. Custom RFQ feasibility first-pass is within 48 hours, NDA first if you prefer. Custom tooling is stored free for 5 years. Payment is 50% advance and 50% before shipment. Sampling is supported at project stage. Production MOQ is quoted per specification and annual volume — there is no invented “MOQ 100” on this page.
Hangzhou does machining, coating, cementing, Class 10,000 assembly, 1 μm-class active alignment when needed, and ships batch reports covering MTF, distortion, BFL and DOF. ISO 9001 is from 2024. The company registered in 2019. The founding team’s 26 years of practice is a separate sentence. On-site audits and scheduled video factory tours are welcome. Those are catalog and custom facts alike. They do not turn a catalog job into tooling.
HANGZHOU FACTORY · ISO 9001
Custom When the Catalog Cannot Close the Drawing
Send a drawing or a sample. First-pass feasibility returns within 48 hours after NDA if you want it. Prototype to mass production is 60 working days. Tooling stays on the shelf free for 5 years. If an FA catalog cell already fits, we will say so rather than open NRE.
60 Working Days
Tooling 5 Years
ISO 9001
When Custom Is the Honest Path
| Best for catalog | Best for custom |
|---|---|
| 2/3″–1.1″ FA, M12, published telecentric | Odd image circle, DLP/UV, spectrometers |
| A 16K line that matches a 40 mm 16K-class cell | A sample with no drawing, reverse engineering |
| ZWA liquid models already named | A waveband or envelope the book does not list |
Mount standards still apply. Custom does not invent a new flange so you can mix C and CS. It builds a prescription the catalog does not stock.
What We Check Before We Open Tooling
- Catalog overlap: if an FA, M12, telecentric or line-scan cell already fits, quote that first.
- NDA: drawings do not move without it if you want it first.
- Five inputs: sensor, working distance, FOV, resolution, environment.
- Clock: 48-hour first-pass, 60 working days to MP, 30-day repeats, tooling 5 years.
- Paper: batch MTF, distortion, BFL, DOF, pass/fail. ISO 9001 only. No invented device badges.
A Buyer Who Paid NRE for a 25 mm FA
Illustrative PO. A 25 mm F1.6 2/3″ C-mount with distortion below 0.05% was labelled “custom OEM” so the file could show a unique part number. Tooling was opened. Sixty working days later the cell was an FA2505A with a new silk-screen. The honest path was catalog, a 30-day repeat if volume followed, and no five-year tool to store. Custom is for the drawing that does not exist on the shelf.
Conclusion
Catalog is the default when the published cell already fits. Custom is 60 working days, 30-day repeats, tooling free for 5 years, 48-hour first-pass, 50/50 payment. Use custom when the drawing is real leftover work — not when the PO wants the word OEM.
Key Takeaways
- Match FA 2/3″–1.1″, M12, telecentric, 4K/8K/16K, ZWA, endoscope modules against the catalog first.
- Quote 60 / 30 / 48 / 5 years exactly. Do not round them.
- NDA before drawings. 50% + 50% before ship.
- ISO 9001 2024. Company 2019. Team practice is 26 years, not the company’s age.
If the drawing is not in the book, send it under NDA and stay on custom optics. If it is a 25 mm FA with distortion below 0.05%, buy the catalog cell and skip the tooling conversation.
Written by Baker Zhao, Founder at Lensmind Optics. Hangzhou factory in the Lin’an optics cluster; ISO 9001 certified 2024. Company registered 2019.
Frequently Asked Questions
When should I buy catalog instead of custom?
When sensor format, mount, FOV and distortion already match a published FA, M12, telecentric or line-scan cell.
How long is custom prototype to mass production?
60 working days is the standard written commitment. Repeat orders are 30 days.
How long is tooling stored?
Custom tooling is stored free for 5 years.
What is the payment split?
50% advance and 50% before shipment.
Is Lensmind a 26-year-old company?
No. The company registered in 2019. Twenty-six years is accumulated practice of the founding team, not company age.
