Lenses for Embedded Vision: Mount Selection, Sensor Matching, and Board-Level Integration
Board-level lens selection for Jetson, Raspberry Pi, and other MIPI-CSI2 camera modules, covering mount choice, sensor and CRA matching, and the power/size/cost tradeoff.
M12（Sマウント）レンズは、3g-15gのネジ山でPCBに取り付けられたホルダーに直接ねじ込むことができ、最大で約1/1.8インチまでのセンサーに対応し（一部のモデルでは1/1.7～1/1.6インチまで対応）、産業用Cマウントレンズに比べてコストが大幅に安いため、組み込みビジョン分野では標準的に採用されています。 CマウントやCSマウントを使用するのは、アプリケーションで可変絞り、より大きなセンサー、あるいはCマウントのカム補正や絞りによってより容易に実現できる産業用グレードの補正が必要な場合に限定してください。
What Lens Mount Is Best for Embedded Cameras?
M12 (S-mount) is the standard for embedded vision: the smallest form factor at 3g-15g, threading directly into a PCB-mounted holder with no adapter plate, at a fraction of the cost of industrial C-mount. Most M12 lenses cover sensors up to roughly 1/1.8 inch (select models reach 1/1.7 to 1/1.6 inch), including the IMX477, IMX219, and IMX708 on most Jetson and Raspberry Pi modules.
Embedded systems lack the design margin of a factory-floor station: a 150g C-mount lens is fine on a fixed stand, but it eats flight time on a drone, adds inertia on a robot arm, and adds fatigue on a handheld scanner. Weight, power, and unit cost compound across every embedded decision.
Thermal range is also wider outside a climate-controlled factory. A camera in a vehicle or outdoor enclosure can swing across -30 degrees C to +70 degrees C in a day, and at F/2 on a small-pixel sensor the depth of focus is only a few microns. All-glass, all-metal construction holds focus more stably than plastic-element designs. Verify thermal focus against the lens datasheet for your temperature range.
| マウント | スレッド | 標準重量 | こんな方に最適 | コレクション |
|---|---|---|---|---|
| M12（Sマウント） | M12×0.5mm | 3g～15g | ロボティクス、ドローン、エッジAI、ボードカメラ | M12レンズ |
| M8 | M8×0.35 または M8×0.5 | 1g～5g | 超小型、内視鏡用、マイクロカメラ | M8 vs M12 |
| CSマウント | 1"-32 UN, 12.526mm flange | 50g～150g | コンパクトな産業用カメラ、Raspberry Pi HQカメラ | CSマウントの基礎知識 |
| Cマウント | 1"-32 UN, 17.526mm flange | 50g～200g | 産業用フルスケール・高解像度検査 | Cマウントレンズ |
C-mount and M12 are different optical systems, not two sizes of the same thing. C-mount uses an internal cam: rotating the focus ring moves lens groups to rebalance aberrations across the focus range and allow an adjustable iris. M12 is a rigid assembly with no moving groups, focused by threading the whole lens in or out, with no aberration rebalancing. Neither is a lesser version of the other; the tradeoff is cam compensation and iris control versus size, weight, and cost.
How Do I Match a Lens to My Embedded Sensor?
A lens-sensor mismatch shows up as vignetting, color shading, or wasted resolution. Four parameters need to line up: image circle versus sensor diagonal, chief ray angle (CRA) versus sensor microlens design, lens MTF versus sensor Nyquist frequency, and back focal length versus your sensor stack.
Image Circle Must Cover the Sensor Diagonal
The lens projects a circular image; your rectangular sensor sits inside it. An image circle smaller than the sensor diagonal vignettes the corners and fails whenever the image must fill the frame. Moderate oversizing is harmless. Circular-image fisheyes that place the whole image circle inside the frame are the deliberate exception.
| センサーフォーマット | 対角線 |
|---|---|
| 1/4インチ | 4.5mm |
| 1/3インチ | 6.0mm |
| 1/2.5インチ | 7.2mm |
| 1/2.3インチ（IMX477クラス） | 7.9mm |
| 1/1.8インチ | 8.9mm |
| 1/1.7インチ | 9.5mm |
| 1/1.6インチ | 10.1mm |
A lens rated for 1/2.5" sensors covers that size or smaller and vignettes on a 1/1.7" sensor. Datasheets list image circle in millimeters or as a format designation, and the two are not always published with matching precision, so verify against your sensor's actual diagonal. See sensor size and lens compatibility for the coverage math.
Resolution: The Lens MTF Must Clear the Sensor's Nyquist Frequency
A 12MP sensor with 1.55µm pixels has a Nyquist frequency of 1 / (2 x pixel pitch), about 322 lp/mm. That is the monochrome limit, and a Bayer color sensor samples each channel more coarsely. If the lens cannot resolve that frequency at your working aperture, the sensor's extra resolution goes to waste. Check the lens MTF chart at your aperture. Above roughly 20%-30% at Nyquist is a reasonable bar. The MTF curve guide explains the charts, and spatial resolution covers the pixel-to-lens relationship.
Work the Focal Length Math Directly
Run your sensor size, field of view, and working distance through the field of view calculator or EFL calculator to get the exact focal length.
How Does Chief Ray Angle Affect Embedded Camera Image Quality?
Chief ray angle (CRA) is the angle between the sensor normal and the central ray of each imaging bundle, the ray through the center of the aperture stop. It rises with image height and is set by the exit pupil distance.
Small-pixel sensors, common at 1.4µm-2.5µm in embedded cameras, use microlenses over each pixel tuned to a specific CRA curve. That curve runs from roughly 0 to 15 degrees at the edge on industrial and machine vision sensors, up to 25 to 35 degrees on mobile-class parts. Pull the curve for your sensor rather than assuming a typical value.
When the lens CRA does not track the sensor's design CRA, red, green, and blue channels fall off differently toward the edges and corner brightness drops, and software cannot fully correct it because the mismatch is wavelength- and angle-dependent at the pixel level, not a uniform gain error. Sensor and lens datasheets both specify a CRA curve. For sub-2µm pixels, check that the two track across the field, not just at the center. The full mismatch mechanics are in the Commonlands chief ray angle and mismatch guide.
CRAの不整合は、セットアップ段階では見落としがちです。なぜなら、画面中央部の画質は問題ないように見えるからです。この問題は、画面の隅やエッジ部分に現れ、多くの場合、特定の照明条件下でのみ発生するか、センサーの改訂によりマイクロレンズの設計が変更された後に初めて明らかになります。新しいカメラモジュールにレンズを採用する際は、現場で色むらが現れてからではなく、事前にCRAの互換性を確認してください。
How Do M12 Lenses Integrate With Jetson and Raspberry Pi Camera Modules?
Jetson Nano, Xavier NX, and Orin modules connect through M12 holders screwed to the PCB on a standard 18mm or 20mm hole spacing, in solderable and snap-in variants. Raspberry Pi and most other MIPI-CSI2 board cameras use the same holder pattern. Common sensors are the IMX477 (Raspberry Pi HQ camera), IMX219 (Camera Module v2), and IMX708. Because M12 has no standardized flange distance, focus is set by how far the lens threads in, and back focal length (BFL) varies by design.
That variability is a feature for board-level integration, not a defect. When you swap camera modules, or the same lens design needs to work across two sensor stacks with different cover glass or IR filter thickness, the fix is a holder of the correct height rather than a different lens.
Confirm holder height against the lens's specified back focal length and your full sensor stack (bare sensor, cover glass, IR filter, any spacer) before finalizing the PCB footprint. Commonlands' M12 lens holder selection guide covers holder height selection and thread engagement in detail.
Multi-camera designs raise the bar further. A stereo pair or array must be matched in focal length and distortion profile across every module, since those set the disparity-to-range scale and rectification accuracy and cannot be trimmed at assembly. Back focal length variation between units, by contrast, is absorbed by focusing each lens individually. Bulk-buying from one production lot reduces optical unit-to-unit variation but does not eliminate it, so verify corner focus on each unit during bring-up, not only the center.
Lens Selection by Embedded Application
Edge AI and NVIDIA Jetson Platforms
Jetson Nano, Xavier NX, and Orin modules pair with MIPI-CSI2 camera boards on M12 holders. A mid focal length covers general-purpose vision at arm's length to room scale. A wider one suits surround-view and obstacle detection, trading fine detail for coverage.
Robotics and AMR Navigation
Mobile robots usually run two camera roles on two lenses: wide-angle or fisheye for obstacle avoidance, where geometric accuracy does not matter, and low distortion for SLAM, where feature matching depends on accurate geometry. See Commonlands' lenses for robotics for dual-camera architectures.
Surveillance and Security
Day/night operation needs both a way to admit near-infrared light (a switchable IR-cut filter, or none) and an IR-corrected lens to hold focus across both bands. A fixed IR-cut filter blocks near-infrared, so the camera goes blind when an 850nm illuminator switches on. Removing it without an IR-corrected lens leaves the night image out of focus, since visible and near-infrared light focus at different planes.
Top M12 Lenses for Embedded Vision
The Commonlands lenses below span 0.8mm to 7.8mm focal length at F/1.45 to F/2.3, covering general-purpose vision, low-light surveillance, low-distortion SLAM, and ultra-wide surround view on Jetson and Raspberry Pi camera modules. All are stocked, all-glass or hybrid designs that thread into a standard M12x0.5mm holder.
| ランク | レンズ | EFL | F値 | 像円 | 組み込み用途における最適な活用法 |
|---|---|---|---|---|---|
| 1 | CIL078 7.8mm M12 lens | 7.8mm | F/2.0 | 9.2mm | 最大1/1.7インチの8MPセンサーを用いた汎用ビジョン（Jetson、Raspberry Pi） |
| 2 | CIL059 5.9mm M12 lens | 5.9mm | F/1.7 | 9.0mm | 高速な汎用カメラ、ステレオカメラ、検査用カメラ。IP67対応モデルもご用意しています。 |
| 3 | CIL326 2.9mm M12 lens | 2.9mm | F/1.45 | 6.8mm | 広角・低照度監視対応、屋外用カメラ向けIP67規格準拠 |
| 4 | CIL034 3.25mm M12 lens | 3.25mm | F/2.3 | 7.8mm | 低歪みSLAMおよび屋外ロボット工学；M12AモデルはIP67対応 |
| 5 | CIL239 1.8mm M12 fisheye | 1.8mm | F/2.0 | 5.2mm | 1/4インチ～1/3インチセンサーを用いた、赤外線補正機能付き昼夜対応障害物回避機能 |
| 6 | CIL207 0.8mm M12 fisheye | 0.8mm | F/1.9 | 4.0mm | 220度の超広角サラウンドビューと障害物検知機能 |
よくある質問
組み込みビジョンシステム用のレンズはどのように選べばよいですか？
まず、センサーフォーマット、マウントタイプ、視野角、動作環境という4つの制約条件から検討を始めます。センサーフォーマットによって、最小のイメージサークルが決まります。組み込みカメラの多くは、コンパクトさを重視してM12を採用しています。作動距離と必要な視野角から焦点距離を算出し、その後、IP保護等級、IR補正、およびセンサーのマイクロレンズ設計とのCRA適合性に基づいて絞り込みを行います。
組み込みカメラには、どのレンズマウントが最適でしょうか？
M12 (S-mount) is standard for embedded vision. It weighs 3g-15g, threads directly into a PCB-mounted holder, and covers sensors up to roughly 1/1.8 inch in most models (select models reach 1/1.7 to 1/1.6 inch). Common examples include the IMX477, IMX219, and IMX708. Choose M8 for ultra-compact designs. Choose C-mount or CS-mount when you need a larger sensor, an adjustable iris, or industrial-grade correction that M12 lenses typically are not designed to provide.
M12レンズはNVIDIA Jetsonカメラで使用できますか？
Yes. Most Jetson-compatible camera modules use M12x0.5mm lens holders. This includes the Raspberry Pi HQ Camera M12 variant, Arducam modules, and other MIPI-CSI2 boards. M12 has no fixed flange distance, so focus is set by threading the lens in or out, which also lets you compensate for different sensor stack thicknesses between camera modules.
組み込みビジョンには、どの焦点距離が必要ですか？
焦点距離は、特定のセンサーと作動距離における視野角を決定します。0.5m～2mの範囲では、4mm～8mmが汎用ビジョンに適しています。2mm～4mmは障害物回避や周囲の視界把握に適しています。8mm～16mmは検査やバーコード読み取りに適しています。正確な焦点距離を求めるには、EFL = (WD × センサー幅) / FOV幅 の式、またはCommonlandsのEFL計算ツールをご利用ください。
CRAは組み込みカメラの画質にどのような影響を与えるのでしょうか？
Chief ray angle (CRA) is the angle at which the lens delivers light to each point on the sensor. Sensor microlenses are tuned to a CRA curve, from roughly 0 to 15 degrees at the edge on machine vision sensors up to 25 to 35 degrees on mobile-class parts, so pull the curve for your sensor rather than assuming one value. A lens CRA that does not track that curve produces color shading and corner falloff that software cannot fully correct, since the mismatch is wavelength- and angle-dependent.
Need Help Matching a Lens to Your Embedded Camera?
Send Commonlands your sensor model, target field of view, and operating environment. The optical engineering team can recommend focal length, aperture, and filter configuration, and confirm CRA compatibility before you commit to a design.