What is distortion?

  1. What is distortion?

Distortion (distortion aberration) means the position in which the image projected through the lens is distorted.

Generally, lenses of wide-angle type are likely to cause barrel type aberration and telephoto lenses are very easy break to pinch winding aberration


<Barrel aberration>
<Pinch Winding Aberration>


2. Method for Calculating Distortion


Optical distortion can be determined through the following formula, where the ideal image height is denoted as Y and the actual image height is denoted as y’:




3. Example of shooting using a fixed-focus lens


8mm固定焦点レンズ Using 8 mm fixed focus lens

Using 12 mm fixed focus lens

12mm固定焦点レンズ Using 25 mm fixed focus lens
Fixed focus lens


A lens with an extremely low amount of distortion is known as a telecentric lens.

Telecentric lenses exhibit low distortion characteristics, making them well-suited for precise measurements.



テレセントリックレンズ テレセントリックレンズ

Telecentric Lens

⇒ For more information about telecentric lenses, please refer to “Types and Features of Telecentric Lenses.”



4. Difference in distortion due to camera sensor size

Even when using the same lens, distortion can vary depending on the camera’s sensor size.





The distortion varies based on the size of the camera sensor, as illustrated below:

Smaller sensor sizes yield lesser distortion,
Larger sensor sizes result in greater distortion.





Regarding the variations in distortion due to sensor size, lens manufacturers may present information in two manners:

1. Noting values for each sensor size,
2. Indicating only the maximum value at the corresponding sensor size.

When presenting values categorized by sensor size,
(As exemplified by our f=25mm lens, compatible with 6 million pixels)  




When indicating the maximum size accommodated (maximum distortion value),
(As illustrated by our f=25mm lens, compatible with 12 million pixels)  





5. Summary:

– Distortion (geometric distortion) refers to the warped state of the imagery projected through the lens.

– For precise measurements or situations where minimizing distortion is crucial, it is recommended to use lenses with extremely low distortion, such as “telecentric lenses.”

– The distortion level varies depending on the camera’s sensor size.

We are also available to assist you in selecting fixed-focus lenses and telecentric lenses. Please feel free to contact our technical support for further assistance.