カメラのピント合わせ方法：M12およびCマウントレンズガイド

カメラのピント調整の背後にある物理的原理とは？

Camera focus happens when light rays from your object converge precisely onto the image sensor. Getting this right is the foundation of every machine vision system.

The distance between lens and sensor where sharp focus occurs is called the back focal length. When you adjust focus, you're changing this distance to match your working distance (how far away your object is).

For M12 lenses, each full rotation moves the lens 0.5mm (thanks to the M12×0.5 thread pitch). This shifts the focus plane by roughly 10-50mm at the object, depending on your focal length. C-mount lenses work differently: they use an internal focus ring rather than threading.

M12レンズのピントはどのように合わせればよいですか？

M12 lens focusing for board level cameras requires systematic adjustment of the threaded mount while monitoring image sharpness. Each rotation = 0.5mm of lens movement. The key is using the ceiling target method to eliminate image tilt.

Thread tolerance mismatches between M12 lenses and holders often cause the lens to sit at a slight angle. This makes one side of your image sharp while the other is blurry, a common problem detailed in our M12 lens technical guide. The fix? Point your camera straight up at a ceiling target. Gravity keeps everything parallel.

Cマウントレンズのピントはどのように合わせればよいですか？

C-mount lenses require a different focusing approach due to their standardized flange focal distance. They have a fixed 17.526mm flange focal distance. You focus by rotating the lens's focus ring, not by threading the whole lens like M12.

Cマウントのフォーカス調整手順

1. Mount lens to camera: Thread C-mount lens fully into mount until flange contacts. This sets the precise 17.526mm spacing.
2. Set aperture: Open to maximum aperture for brightest view during focusing, then stop down to working f-number after focusing.
3. Rotate focus ring: Turn the focus ring (not the entire lens) while viewing live image. Most C-mount lenses have ~270° of rotation.
4. Verify across field: Check center and corners at working aperture. Industrial C-mount lenses should maintain <5% MTF variation.
5. Lock focus ring: Tighten set screws on focus ring or apply removable thread locker to prevent drift during operation.

Commonlands offers a comprehensive selection of C-mount lenses optimized for 1/2" to 1" sensors, with focus rings designed for smooth adjustment and reliable locking. These lenses feature low-distortion designs ideal for measurement applications.

オーバーシュート法を使って、集中力のピークをどのように見つければよいですか？

The overshoot-and-return technique ensures you find true peak focus, not a local maximum. By deliberately passing through the point of best focus and then returning with finer adjustments, you eliminate backlash effects and verify you've found the global optimum.

Here's how it works: deliberately pass through the point of best focus, then return with finer adjustments. M12 threads have 10-30μm of mechanical play (backlash), so always approach your final focus position from the same direction. This method works for both manual adjustment and when reviewing MTF measurement curves.

どのフォーカスロック方式を選べばいいですか？

The choice of focus locking method for board level cameras impacts long-term stability, serviceability, and production throughput. Each method offers distinct advantages for different applications and production volumes when securing board level lenses.

被写界深度はどのように計算すればよいですか？

Proper depth of field calculations ensure your entire object range remains in acceptable focus. Your DOF depends on focal length, aperture (f-number), sensor size, and working distance.

Visit our Camera Depth of Field Calculator to determine optimal focus settings for your specific lens/sensor combination and working distance requirements.

組み立て前に適切な露出を設定するにはどうすればよいですか？

Correct exposure settings must be established before final focus locking to ensure consistent image quality across production. Using standardized targets like ColorChecker gray patches or OECF charts provides repeatable exposure calibration that eliminates unit-to-unit variation in brightness and contrast.

簡単な露出設定の手順

よくある集中力の問題とその解決策とは？

Focus issues cost production time and reduce yield. Understanding root causes enables targeted solutions that maintain long-term stability. Our experience from assembling thousands of camera modules has identified these critical issues and proven solutions.

プロ向けカメラモジュール組立サービス

Commonlands provides complete camera module assembly with professional focusing services starting at 100 pieces minimum order quantity. Our clean room facilities and precision alignment fixtures ensure consistent, production-ready results for robotics, surveillance, and automotive applications.

Ready to eliminate focusing challenges? Our team handles the complex alignment process so you can focus on your application. Minimum order quantity: 100 pieces. Learn more about our assembly services or contact our engineers to discuss your requirements.

アクティブ・アライメントとは？（OEM生産限定）

Active alignment optimizes focus while monitoring image quality in real-time, improving yield for high-volume OEM production. This technique is only cost-effective for large production runs due to significant capital equipment costs and complex changeover requirements between different camera models.

The process uses 6-axis positioning with MTF or contrast feedback to compensate for component tolerances by optimizing each unit individually. This increases first-pass yield from ~85% to >98%.