組み込みビジョンカメラ用M12レンズ

用途に合ったSマウントレンズの選び方

M12レンズの選定には、画角、解像度（MTF）、および機械的適合性の3つの要素が重要となります。これらを 適切に決定すれば、残りの仕様（F値、IRフィルタ、シーリング）は、 使用環境に応じて自然に決まります。以下の注記では、各パラメータと、組み込みシステムにおいて最も重要な トレードオフについて解説します。

画角と焦点距離に関する考慮事項

• Field of View (FOV) Requirements Focal length sets how much scene the lens captures. Short focal lengths give mobile robots the wide coverage they need for situational awareness; long focal lengths resolve fine detail for inspection at a distance. Wide-angle M12 lenses generally carry more barrel distortion, which you can correct in software or avoid outright with a low distortion design. Telephoto S-mount lenses hold geometric accuracy over a narrow field. Model coverage, distortion included, with our FOV Calculator, then check the result against the lens’s measured distortion data.
• 被写界深度（DOF）の最適化 被写界深度とは、許容できるほど鮮明に写る距離の範囲のことです。F値を高くすると被写界深度は広がりますが、 光量も減少するため、照明条件が変動する環境で動作するボードカメラにとっては大きな制約となります。 固定焦点のM12モジュールは、再フォーカスを回避するために十分な被写界深度に依存しているため、作動距離が変動する場合は、 公称距離だけでなく、両極端の距離でも鮮明度を確認してください。当社の 被写界深度計算ツールは、 許容可能なボケを推定する際にピクセルピッチを考慮に入れています。
• Sensor Format Compatibility The lens image circle must equal or exceed the sensor diagonal, or the corners vignette. A larger-than-needed image circle is usually acceptable for coverage, since the sensor samples the well-corrected center of the field; run the same CRA, clearance, filter-stack, and MTF checks as any pairing. You do pay for size, weight, and glass you never use, so the format-matched lens usually wins on cost. A 1/2.3" optimized S-mount lens works fine on a 1/3" sensor; the reverse produces dark corners. Our Focal Length Calculator maps sensor format to the focal length that produces your target FOV.

光学性能仕様

• Resolution and MTF Performance The Modulation Transfer Function describes how much contrast the lens preserves at each spatial frequency. It is the standard measure of lens sharpness. Our starting point is roughly 20% to 30% MTF at the sensor’s Nyquist frequency (1 / (2 × pixel pitch)). That band is a Commonlands rule of thumb rather than a published standard, so validate it against the contrast your own task needs. When lens contrast at Nyquist falls well below it, the lens rather than the sensor sets the resolution limit. Over-specifying MTF adds cost without visible benefit once pixel size becomes the limit, so match the lens to the sensor you actually use. Commonlands publishes measured MTF data on request.
• F値と集光力 F値は集光力を決定します。像面の照度は1/N²に比例するため、F1.4のレンズは F2.0のレンズに比べて約2倍の光量を取り込むことができます。 明るい絞り（F1.4～F2.0）は、低照度下での S/N比を高め、動きのブレを抑える短い露光時間を可能にしますが、一般的に 画角の端で収差が目立ちやすくなり、被写界深度も浅くなります。被写体が十分に明るく、速度よりも構図が重視される場合は、 F2.8前後の適度な絞り値を選ぶ方が、多くの場合、より良いバランスとなります。
• Chief Ray Angle (CRA) Matching CMOS sensors place microlenses over each photodiode, tuned for a ray incidence angle that increases toward the sensor edge. When the lens CRA diverges too far from the sensor’s microlens design, off-axis light partially misses the photodiodes and produces wavelength-dependent shading: the pink-green corner tint that is difficult to remove in post-processing. Compare the lens CRA plot against the sensor’s published curve point by point across image height rather than as a single number. How much mismatch you can absorb depends on the working F-number and the width of the ray cone, the wavelengths in use, the pixel and filter stack, and the corner shading and MTF loss your pipeline tolerates. Monochrome sensors escape the color shading but still lose light off-angle. Global shutter machine vision sensors such as the OV9281 and AR0234 publish CRA curves in their datasheets.

環境的および機械的要因

• Ingress Protection Requirements An IP67-rated M12 lens seals at the barrel, which makes a window-less build an architecture option: dropping the protective window and its two air-glass surfaces means less stray light and better contrast, but take that option only after validating the full installed assembly against your actual exposure. The rating applies to the tested lens variant in its mounted configuration under the dust and water exposures of IEC 60529, and it does not protect the sensor board or the rest of the camera. For outdoor builds, most teams start their evaluation with the sealed IP67 variant; a washdown jet sits outside what the IP67 immersion test covers, which moves the evaluation to a jet-rated IP6K9K option. Both cases still need the installed assembly validated against the actual exposure, and the housing gets sealed on its own terms; controlled indoor environments can save the cost with standard barrels.
• Thermal Stability Considerations All-glass M12 lenses are generally rated for −40°C to +85°C operation. A temperature rating is not a focus guarantee: whether focus holds across that range is a property of the assembled lens, holder, and sensor together, and is verified by measuring focus or MTF across the temperatures the camera will see. Treat element material as descriptive data rather than a thermal rule. Glass and optical plastics differ in expansion and dn/dT, but the net focus shift of a design depends on how the prescription, barrel, holder, and sensor stack combine, and a well-athermalized hybrid glass-plastic design can hold focus over temperature better than an all-glass one. Screen on outcomes instead of construction: shortlist lenses with a stated operating-temperature range, then qualify the shortlisted assembly with an over-temperature focus or MTF measurement, which Commonlands can run on request.