Fixed-focus lenses, also known as fixed-focal-length lenses, are a cornerstone of optical technology, offering simplicity, reliability, and cost-efficiency. Unlike zoom lenses, fixed-focus lens maintain a single focal length, making them ideal for applications requiring consistent image quality without manual adjustments. Whether you’re deploying them in surveillance systems, industrial automation, or automotive cameras, understanding their parameters and best practices is critical.

Understanding Fixed-Focus Lenses: Core Parameters

Fixed-focus lens are engineered for precision, but their effectiveness hinges on mastering their technical specifications. Here are the critical parameters to evaluate:

1. Focal Length & Field of View (FOV)

The focal length determines the angle of view and magnification. Shorter focal lengths (e.g., 2.8mm) provide wider FOVs, suitable for panoramic surveillance, while longer focal lengths (e.g., 12mm) narrow the FOV for detailed inspections. TOWIN’s fixed-focus lenses, such as the M12 Low Distortion Lens, offer focal lengths ranging from 2.8mm to 16mm, catering to diverse needs.

Low-distortion-4.2mm-fixed-focus lenses

2. Aperture & Light Sensitivity

The aperture (f-number) controls light intake. A lower f-number (e.g., f/1.4) allows more light, enhancing low-light performance. TOWIN’s Low Light Sensitive Fixed-Focus Lenses feature wide apertures, ensuring clarity in dim environments like parking lots or nighttime traffic monitoring.

3. Resolution & Image Quality

Resolution is measured in megapixels (MP). TOWIN’s fixed-focus lens support up to 12MP resolution, delivering crisp images for high-definition surveillance. Their multi-coating technology reduces glare and improves contrast, critical for day/night cameras.

4. Mount Type & Compatibility

Fixed-focus lenses come in various mounts:

• M12/S-Mount: Compact and threaded directly into PCB cameras, ideal for embedded systems.
• C-Mount: Used in machine vision and industrial cameras, with a 17.526mm flange distance.
• CS-Mount: Designed for CCTV and IP cameras, with a 12.526mm flange distance.

TOWIN’s CS-Mount Fixed-Focus Lenses include manual iris, DC auto-iris, and P-iris variants, ensuring compatibility with modern surveillance systems.

5. Distortion & Chromatic Aberration

Fixed-focus lenses must minimize distortion (e.g., barrel or pincushion) and chromatic aberration (color fringing). TOWIN’s Fisheye Fixed-Focus Lens balance ultra-wide angles with minimal distortion, while their Wide Angle Lenses correct chromatic errors for true-color reproduction.

Low-distortion-3.4mm-fixed-focus-industrial-lens

5 Tips & Precautions for Fixed-Focus Lens Users

1. Choose the Right Focal Length for Your Application

Selecting the correct focal length is non-negotiable. For instance:

• A 2.8mm fixed-focus lens suits retail stores needing broad coverage.
• A 12mm lens is better for license plate recognition at entry gates.

Pro Tip: TOWIN’s M12 Lens Selector Tool helps match focal lengths to your use case.

2. Prioritize Low-Light Performance in Dim Environments

Fixed-focus lens with wide apertures (e.g., f/1.2) excel in low light. TOWIN’s Low Light Sensitive Lenses incorporate IR-corrected multi-coating, ensuring 24/7 performance in security applications.

3. Ensure Compatibility with Camera Mounts

Mixing incompatible mounts (e.g., C-mount on a CS-mount camera) causes focus issues. TOWIN’s lenses are labeled clearly, and their team provides mount compatibility guides.

4. Regularly Clean Lenses to Maintain Image Quality

Dust and fingerprints degrade image sharpness. Use a microfiber cloth and lens-cleaning solution. TOWIN’s lenses feature anti-reflective coatings, but proper maintenance extends their lifespan.

5. Avoid Mechanical Stress on Lens Barrels

Fixed-focus lenses lack zoom mechanisms, so avoid twisting or applying pressure to the barrel. TOWIN’s ruggedized Automotive Fixed-Focus Lens resist vibrations, making them ideal for vehicle-mounted cameras.

Why TOWIN’s Fixed-Focus Lenses Stand Out

TOWIN specializes in high-performance fixed-focus lens tailored for:

• Surveillance: CS-mount lenses with IR correction for day/night cameras.
• Industrial Vision: C-mount lenses for machine vision and 3D inspection.
• Automotive: Miniature M12 lenses for ADAS and in-cabin monitoring.

Their lenses are manufactured in China with stringent quality control, ensuring fast delivery and competitive pricing.

5mm IR corrected CS mount fixed-focus lens

Conclusion

Fixed-focus lenses offer unmatched reliability for applications demanding consistent image quality. By selecting the right focal length, prioritizing low-light performance, and ensuring proper maintenance, users can unlock their full potential. TOWIN’s diverse range of fixed-focus lens—from low-distortion M12 variants to high-resolution CS-mount models—provides tailored solutions for every need.