
Choosing the right lens is one of the most critical steps in building any camera system. With hundreds of lenses available, mismatched mounts, incompatible sensor sizes, and incorrect focal lengths can lead to blurry images, dark corners, wasted time, and costly redesigns. Engineers, buyers, and system integrators often struggle to sort through technical specifications to find exactly what their project needs.
At Towin, we designed our customized lens search tool to solve this problem. Our powerful product filter allows you to search lenses precisely by mount, sensor size, effective focal length (EFL), and other key parameters. In this guide, we break down how to use our filter efficiently, explain core lens parameters, and show you how to select the best lens for your application in minutes.

Customized Lens Search
The mount connects the lens to the camera body. A mismatched mount makes proper installation and focusing impossible.
| Mount Type | Applications | Benefits |
|---|---|---|
| M12 / S-Mount | Security cameras, drones, automotive, IoT | Small size, lightweight, cost-effective |
| C-Mount | Industrial vision, machine vision, professional cameras | Standard 17.526mm flange distance, high stability |
| CS-Mount | CCTV, compact surveillance | Shorter flange distance, works with adapter for C-Mount |
| Custom Mounts | Specialized industrial & automotive systems | Tailored for unique camera designs |
The lens image circle must fully cover your camera sensor. Using a lens designed for a smaller sensor causes vignetting.
Common sensor sizes:
Rule of thumb:
EFL determines how wide or narrow your camera’s view is.
1: Select Mount & Sensor Size First
Start with the two most important compatibility parameters to filter out mismatched lenses immediately.
2: Set EFL or FOV
Choose your desired focal length or field of view to match viewing distance and coverage area.
3: Add Application-Specific Filters
Select resolution, iris type, F-number, TTL, and special features such as IR correction or waterproofing.
4: Review Filtered Results
Browse matching lenses, check datasheets, compare specs, and request samples.
5: Request Custom Lens Support
If no standard lens fits your specs, contact Towin for custom design.

Lens Selection Tool
Q: What happens if mount and camera do not match?
A: The lens cannot be installed correctly, leading to focus failure and unusable images.
Q: Can I use a C-Mount lens on a CS-Mount camera?
A: Not directly. You need a 5mm adapter ring to adjust flange distance.
Q: What does IR corrected mean?
A: IR corrected lenses focus visible and infrared light (850nm/940nm) at the same plane, ensuring clear night vision.
Q: How do I choose EFL for long-distance monitoring?
A: Use longer focal lengths to narrow the field of view and magnify distant objects.
Q: What if I need a special lens not in your catalog?
A: Towin supports fully customized lens design based on your mount, sensor, EFL, FOV, size, and environmental requirements.
Finding the right lens no longer requires hours of manual searching. With Towin’ customized lens search filter, you can quickly filter by mount, sensor, EFL, and other critical parameters to find compatible, high-performance lenses for any vision system.
Whether you need standard lenses or fully custom designs, Towin provides reliable optical solutions for security, automotive, industrial, drone, and IoT applications.