When it comes to selecting lenses for various camera systems, especially for industrial, scientific, and surveillance applications, C-Mount lenses are an incredibly popular choice. High-quality imaging demand in microscopy, machine vision, and security cameras makes C-Mount lens focal length choices vital.

What are C-Mount Lenses?

C-Mount lenses are a type of lens that uses a standardized thread of 1-inch in diameter with 32 threads per inch. These lenses find wide use in industrial, scientific imaging, and surveillance cameras for sharp, detailed images. They are popular for both 2D and 3D imaging applications, as well as high-definition video recording.

Why is Focal Length Important for C-Mount Lenses?

Focal length is the distance between the lens’s optical center and the image sensor when the subject is in focus. The focal length impacts the field of view, magnification, and depth of field. In general, lenses with shorter focal lengths offer a wider field of view, while lenses with longer focal lengths provide higher magnification and narrower field of view.

For C-Mount lenses, focal length matters greatly as they serve apps needing field of view, image clarity, and working distance.

20MP 12mm low distorton C-mount FA lens

Common Focal Length Options for C-Mount Lenses

1. Wide-Angle C-Mount Lenses (Focal Length: 4mm to 12mm)

Wide-angle C-Mount lenses are perfect for applications that require a broad field of view. These lenses commonly serve surveillance, security cameras, and industrial apps needing large-area monitoring. A focal length in the range of 4mm to 12mm offers a wide field of view, making them ideal for situations where you want to capture as much detail as possible from a close distance.

2. Standard C-Mount Lenses (Focal Length: 12mm to 25mm)

The standard focal length range of 12mm to 25mm is commonly used in everyday imaging tasks. These lenses are versatile, offering a good balance between field of view and magnification. They frequently serve machine vision, inspection systems, and low-to-mid-range surveillance setups. They are great for capturing moderate details from a variety of distances.

3. Telephoto C-Mount Lenses (Focal Length: 25mm to 75mm)

Telephoto C-Mount lenses suit apps needing high magnification and a narrow field of view. These lenses let you zoom on distant subjects without moving the camera, ideal for long-range surveillance, monitoring, and detailed optical inspections.

4. Very Long Focal Length C-Mount Lenses (Focal Length: 75mm and above)

For those specialized tasks that require extreme magnification, C-Mount lenses with focal lengths of 75mm and beyond come into play. These lenses frequently serve high-precision imaging tasks like microscopy and astronomy. They provide highly detailed and magnified images, allowing for inspection of the finest elements.

How to Choose the Right Focal Length for Your Application?

• Field of View: Do you need to capture a wide area or focus on specific details? For a broader field of view, opt for a wide-angle lens. For more magnified images, go for a longer focal length lens.
• Working Distance: The gap between your lens and the captured object also ranks as a critical factor. Shorter focal lengths need closer working distances; longer ones work effectively from farther away.
• Magnification Requirements: If you need to inspect small details, longer focal lengths are preferred. For general purposes, a standard focal length is ideal.

C-mount IR corrected CCTV lens

Advantages of Different Focal Lengths

• Wide-Angle Lenses: These lenses provide a large field of view and are ideal for capturing broad scenes. They are great for surveillance and security applications.
• Standard Lenses: Offer a balanced field of view and magnification, making them versatile and suitable for most industrial and inspection tasks.
• Telephoto Lenses: These lenses excel at magnifying distant objects, making them ideal for situations where zooming is necessary without moving the camera.
• Very Long Focal Length Lenses: Perfect for high-precision tasks like microscopy, where minute details need to be captured with great clarity.

Focal Length and Depth of Field in C-Mount Lenses

Depth of field is another critical factor influenced by focal length. A longer focal length lens tends to have a shallower depth of field, meaning the area in focus will be smaller. In contrast, a shorter focal length lens provides a larger depth of field, allowing more of the scene to remain in focus.

FAQs

What is the best focal length for general surveillance?

For general surveillance purposes, C-Mount lenses with focal lengths ranging from 4mm to 12mm are typically preferred. They offer a good balance of field of view and image clarity, making them ideal for monitoring large areas.

Can I use a long focal length lens for close-up inspections?

While longer focal length C-Mount lenses (e.g., 25mm and above) offer high magnification, they are usually better suited for distant subjects. For close-up inspections, a standard focal length lens (12mm to 25mm) is often more effective.

How does focal length affect image quality?

Focal length impacts magnification and field of view, but the quality of the image also depends on factors like aperture, lens coatings, and sensor resolution. Longer focal length lenses tend to provide more detailed images at a distance.

40mm C mount IR corrected machine vision lenses

Conclusion

Understanding the focal length options for C-Mount lenses is essential for selecting the right lens for your camera system. By considering factors such as field of view, working distance, and magnification needs, you can choose the optimal lens for your specific application. Whether you are setting up a security system, working in a laboratory, or designing an industrial inspection system, the right C-Mount lens can make all the difference in the quality of your images.