Blurry images are typically caused by incorrect focus distance or improper installation. First, thread your M12 lens into the holder until you go past focus. Then, while viewing a live image, slowly rotate the lens counterclockwise (loosening) in small increments (1/8 turns) until your subject comes into sharp focus. The 0.5mm thread pitch means each full rotation moves the lens 0.5mm, so small adjustments make a big difference.

Quick troubleshooting: If you can't achieve focus, check that: (1) your subject is beyond the minimum object distance (typically 20cm for wide angle lenses) and (2) the lens holder height matches your sensor's requirements. Once focused, apply thread locker or use a lock nut to prevent the lens from rotating during use.

For a complete focusing procedure with test patterns and tips, see our step-by-step camera focusing guide.

While M12-to-C-mount adapters exist, there is a possibility these won't work due to mechanical back focal length (MBFL) incompatibilities. The critical issue: C-mount cameras have filters built in with holder mechanics that prevent the lens from moving close enough to the sensor: the M12 lens usually can only get as close as 4-5mm away from the sensor. If your M12 lens has an MBFL less than ~4mm (common for wide-angle lenses), it physically cannot get close enough to the sensor to achieve focus - the image will be permanently blurry regardless of lens adjustment.

How to check compatibility: Look up your M12 lens's MBFL in its datasheet - this is the distance from the lens mounting surface to the sensor when focused at infinity. If the MBFL is less than 4mm, the lens won't work with most C-mount cameras, even with adapters. Additionally, many C-mount cameras have protruding IR cut filter holders or protective windows that increase the minimum distance to 6-8mm, making even more M12 lenses incompatible.

Working alternatives: (1) Choose M12 lenses specifically designed with long MBFL (>8mm) for C-mount adaptation - usually telephoto focal lengths. (2) Use a C-mount camera with a recessed sensor design or removable filter holder. (3) Machine a custom adapter that allows the M12 holder to sit inside the C-mount thread. (4) Select proper C-mount lenses instead - they're designed for this mount and will perform better. Remember that even if you achieve focus, the C-mount camera's larger sensor may exceed the M12 lens's image circle, causing severe vignetting.

Your actual field of view depends on both your lens focal length and sensor size. As a quick reference: with a 1/2.8" sensor (6.2mm diagonal), a 2.8mm lens gives ~90° horizontal FoV, a 3.6mm gives ~70°, a 6mm gives ~45°, and a 12mm gives ~23°. Larger sensors capture more of the image circle, resulting in wider fields of view with the same lens.

Important for wide angle lenses: Be aware that lens distortion affects your usable field of view. Standard wide angle lenses often have 5-15% barrel distortion, which curves straight lines but fits more content in the frame. Our low-distortion lenses (<1% distortion) maintain geometric accuracy but may have a slightly narrower field of view. Choose low-distortion for measurement/inspection applications, and standard distortion for general surveillance where maximum coverage matters more than geometric precision.

Use our Field of View Calculator to get exact angles for your specific lens/sensor combination - just input your focal length and sensor dimensions.

Every lens has a Minimum Object Distance (MOD) - the closest distance at which it can focus. Standard M12 lenses can focus at any object distance if the correct height lens holder is used, however, at less than 250mm the corners may be blurry if you use an infinite conjugate M12 lens. Additionally, remember that the MOD is measured from the front of the lens, not the sensor, so account for your lens holder height.

Solutions for close-up work: If you need to focus closer, you have three options: (1) use a taller lens mount to move the lens further away from the sensor, (2) add spacer rings between the lens and holder to increase the back focal distance, or (3) select a shorter focal length lens which generally allows closer focusing. Note that at very close distances, field curvature becomes more pronounced if using an infinite conjugate optimized M12 lens - the corners may be slightly out of focus when the center is sharp. Using a smaller aperture (higher f-number) helps maintain edge-to-edge sharpness.

Contact us for lens recommendations based on your working distance requirements. Our CIL945, CIL142 and CIL121 are finite conjugate optimized.

Dark corners (vignetting) typically mean your lens image circle is too small for your sensor. Check that your lens format (e.g., 1/2.8", 1/1.8") matches or exceeds your sensor size. Color shading toward the edges often indicates a Chief Ray Angle (CRA) mismatch between your lens and sensor. Modern CMOS sensors have microlenses that expect light to arrive at specific angles - when the lens CRA doesn't match the sensor CRA, you'll see color shifts or brightness fall-off at the image edges.

How to verify compatibility: Compare your sensor's CRA specification with the lens CRA shown in its mechanical drawing. A mismatch over 5° for linear CRA sensors typically can cause color shading issues.

Learn more about avoiding these issues in our article on lens chief ray angle and sensor matching.

Whether your entire scene stays in focus depends on your depth of field (DoF), which is controlled by three factors: aperture, focal length, and distance to subject. Wide angle M12 lenses (>80°) typically keep everything from 50cm to infinity in acceptable focus. Telephoto lenses (12mm+) or larger apertures (F1.4-F2.0) create much shallower depth of field, requiring more careful consideration.

Practical guidelines: For machine vision, barcode reading, or inspection applications where everything must be sharp, choose a smaller aperture (F2.8 or higher) and ensure your working distance range falls within the calculated DoF. For surveillance or general imaging where some background blur is acceptable, you can use faster lenses. Remember that smaller apertures reduce light transmission, so you'll need better lighting or higher sensor gain.

Calculate your exact depth of field range using our Depth of Field Calculator - input your lens specs and focus distance to see the near and far limits of sharp focus.

M12 lenses (S-mount) are ideal for compact applications, board-level cameras, and sensors up to 1/1.8". They're cost-effective, lightweight (typically 2-10g), and perfect for drones, embedded vision, and high-volume products. The 12mm diameter limits optical complexity, so they work best with sensors under 12MP and in good lighting conditions.

C-mount lenses are the professional choice for machine vision and industrial applications. With a 25.4mm threaded diameter mount and 17.526mm flange distance, they accommodate larger, more optics. Choose C-mount when you need: optimized across a large working distance range, sensors larger than 1", resolution above 12MP, motorized iris/focus/zoom, or specialized optics like telecentric designs. The trade-off is size (10-50x heavier) and cost (5-20x more expensive). C-Mount lenses do not necessarily have better performance than M12 lenses due to the mechanical back focal length constraint that requires more / larger glass elements to correct for.

Quick decision guide: Use M12 for embedded/OEM applications where size and cost matter. Use C-mount for industrial/scientific applications where optical performance is critical. Note that C-mount requires a camera with C-mount threading - you cannot adapt M12 to C-mount due to the different flange focal distances.

CMOS sensors are sensitive to infrared light (700-1100nm) which humans can't see. Without an IR cut filter, daylight images appear washed out with incorrect colors - vegetation looks white/pink and black fabrics appear purple. You need an IR cut filter for accurate color reproduction in any application with visible light imaging.

Lens-integrated filters: Lens-integrated IR filters (like our M12A650 series) are convenient and protect the lens rear element, but these are glued and cannot be removed so be sure to purchase the correct variant. For outdoor/dual-use cameras, consider motorized IR cut filter switchers that automatically switch based on lighting conditions or using a Dual bandpass filter.

When to skip the IR filter: Use lenses without IR filtration (our M12ANIR series) for: night vision with IR illumination, multispectral imaging, or applications specifically detecting IR radiation. Remember that without IR filtering, you cannot achieve accurate visible color imaging even with proper ISP tuning.

Best M12 lens solution: Vibration, thermal cycling, and handling can cause M12 lenses to rotate and lose focus. The most reliable solution is using a UV+heat dual cure adhesive or standard UV cure adhesive. Apply a small drop to the lens threads then complete final focusing - it remains adjustable during setup. Then, cure with UV light source before moving the camera, and finally cure using heat to ensure adhesive within the shadow zones is fully cured.

Alternate M12 lens solutions: You can also use a M12 S-Mount lock nut that tightens against the lens once focused. Or, use standard plumbers tape / teflon tape wrapped around the lens threads.

For C-mount lenses: These typically use a set screw in the lens barrel. Industrial C-mount lenses often include locking mechanisms built into the focus ring. Always verify the lock is engaged before deploying the camera. However, C-Mount lenses are generally more prone to failure over vibration as a result of these internal moving parts.

Select your focal length based on: (1) what you need to see (field of view), (2) how far away it is (working distance), and (3) your sensor size. The basic formula: Focal Length = (Working Distance × Sensor Size) / Field of View Width. For example, to image a 2-meter wide area from 3 meters away with a 1/2.8" sensor (4.8mm width): 3000mm × 4.8mm / 2000mm = 7.2mm focal length needed.

Remember that shorter focal lengths (wide angle) show more area but with less detail, while longer focal lengths (telephoto) show less area but with greater detail. If unsure, choose a varifocal C-mount lens (2.8-12mm range) to experiment before committing to a fixed focal length.

Yes! Commonlands offers complete camera modules and camera module focus+glue assembly services for OEM customers. We handle everything from optical design and sensor selection to final assembly and quality testing. Our services include: lens optimized for your sensor and application, sensor integration with leading image sensors from Sony, OmniVision, and OnSemi, selection of lens holders and mounting solutions, and complete module assembly including lens focusing and thread locking.

Typical project scope: We work with customers from prototype through production volumes (100 to 100,000+ units annually). Our team can optimize existing designs for cost reduction, improve optical performance, or develop entirely new camera modules to your specifications. We maintain inventory of common lenses for rapid prototypes, with production lead times of 6-12 weeks depending on customization level.

Getting started: Contact our engineering team with your target specifications: resolution, field of view, working distance, environmental requirements (IP67, operating temperature), interface type (MIPI, USB, LVDS), and target price point. We'll provide a detailed proposal including optical simulation results, mechanical drawings, and sample availability. Most customers start with our standard lens + sensor combinations for proof of concept before moving to custom designs.