The Small 1x1 of Machine Vision
Optics in Machine Vision
Understanding and Applying Lens Selection
Optics are a fundamental part of every machine vision system - and at the same time one of the most common causes of unstable inspection results. In many projects, lens selection is considered too late or treated as an isolated task, resulting in insufficient image quality, measurement errors or unnecessary design iterations.
The key point is that optics never operate in isolation. They must be precisely matched to the sensor, pixel size, working distance and lighting.
If you would like to understand the fundamentals of industrial machine vision, start with our introduction to What Is Machine Vision?
What sensor sizes are available - and why are they important?
Sensor size describes the physical area onto which the image is projected. In industrial machine vision, sensor sizes are typically specified in inches, such as 1/3", 1/2", 2/3" or 1".
Smaller sensors such as 1/3" and 1/2" are commonly used in compact and cost-sensitive applications. Larger sensors - such as 2/3" and 1" - are standard in many industrial inspection systems because they provide a wider field of view or higher image detail. Even larger sensor formats are used in high-resolution applications.
Sensor size directly affects the field of view. With the same lens, a larger sensor captures more of the object. At the same time, the lens must be compatible with the sensor size, as every lens is designed for a specific image circle. Exceeding this image circle results in vignetting or blurred image areas.
Sensor size is also closely related to camera technology. Differences in sensor architecture and pixel size are explained in more detail in Camera Technologies in Machine Vision.
Choosing the right camera is closely linked to sensor size. An overview of available camera models and sensor formats can be found in Industrial Cameras.
What mount types are available - and what do they mean?
The lens mount defines the mechanical interface between the camera and the lens. It determines how the lens is attached and its distance from the sensor.
The most widely used standard in industrial machine vision is the C-mount, which offers broad compatibility and is typically used with sensors up to approximately 1".
The CS-mount is mechanically similar but has a shorter flange focal distance. CS-mount lenses cannot be mounted directly on C-mount cameras, whereas C-mount lenses can often be used on CS-mount cameras with an adapter.
For larger sensors or applications requiring higher optical performance, F-mount systems—originally developed for photography—are frequently used. Additional mount types are available for specialised applications.
In practice, the mount ensures mechanical compatibility, but it does not determine whether a lens is optically suitable for a given application.
An overview of compatible lenses for different mount types is available in Machine Vision Lenses.
What types of lenses are used in machine vision?
Different applications require different lens types, each designed for specific optical characteristics and use cases.
Standard lenses cover a broad range of applications and are widely used for general inspection tasks. They provide an excellent balance between performance and cost.