Lens Resolution Parameters-Knowledge Encyclopedia-Shenzhen Kai Mo Rui Electronic Technology Co. LTD

Lens Resolution Parameters

Source：Shenzhen Kai Mo Rui Electronic Technology Co. LTD2026-06-24

Definition of Resolution

The minimum distance between two object points that can be distinguished is defined as the object-side resolution of a lens, denoted as Resolution(Object), with the unit of micrometer (µm).

It is important to note that this is an inherent parameter of the lens itself, which only characterizes the resolving power of the lens and has nothing to do with the pixel count of the camera. It directly indicates the size of the blurred spot formed when an ideal point source is imaged through the lens; a smaller value means better performance.

Lens resolution is correlated with its aperture size (or numerical aperture, NA). Lens imaging is essentially an optical diffraction process. A smaller aperture (larger F-number) leads to more severe diffraction spots and consequently degraded resolution.

Besides, even with a large aperture, uncorrected optical aberrations will also compromise image sharpness. For this reason, some FA lenses do not deliver the sharpest picture at their maximum aperture.

Distinction from Detection / Measurement Accuracy

The "accuracy" required by most customers actually refers to the physical object size represented by a single pixel. It can be calculated by dividing the camera pixel size by the optical magnification:

Accuracy=Pixel Size÷Optical Magnification

Equivalently, it can also be calculated as total field of view divided by total pixel quantity, yielding the same result.

For example: a 5MP camera with 2.2 µm pixel size paired with a 0.5× lens gives an accuracy of 2.2 μm÷0.5=4.4 μm. Measuring a 25 µm line width requires 5~6 pixels, and every single-pixel shift in the image changes the measured value by 4.4 µm.

Evidently, this calculation does not involve lens resolution at all; measurement accuracy is directly determined by camera pixel specifications and field of view.

Matching Lens Resolution with Camera Resolution

After clarifying these two frequently confused parameters, we introduce the matching principle between lens resolution and camera resolution:

Multiply the nominal object-side resolution of the lens by magnification to obtain image-side resolution;
Compare this image-side resolution with twice the camera pixel size.
A perfect match is achieved when the two values are approximately equal. Whichever value is larger becomes the bottleneck limiting the overall performance of the vision system.
Formula reference:
Lens Object Resolution×Magnification
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