# barrelDistortion The first coefficient for determining the radial distortion applied to pixels rendered using the camera. ``` var barrelDistortion: Float { get set } ``` ## Discussion Light passing through any lens produces some amount of radial distortion, which a renderer can compute based on the [`focalLength`](/documentation/ModelIO/MDLCamera/focalLength) property. However, some lenses or aesthetic designs introduce additional distortion. A renderer can model radial distortion using the following equation, in which `r` is the radial distance from a pixel to be rendered to the center of the projection, and `r’` is the new radial distance to that pixel accounting for distortion: `r' = r * (1 +` [`barrelDistortion`](/documentation/ModelIO/MDLCamera/barrelDistortion) `* r^2 +` [`fisheyeDistortion`](/documentation/ModelIO/MDLCamera/fisheyeDistortion) `* r^4)` A nonzero [`barrelDistortion`](/documentation/ModelIO/MDLCamera/barrelDistortion) value sufficiently describes the distortion characteristic of most lenses. To simulate other lenses—such as security cameras, plastic toy lenses, or VR headsets—use both the [`barrelDistortion`](/documentation/ModelIO/MDLCamera/barrelDistortion) and [`fisheyeDistortion`](/documentation/ModelIO/MDLCamera/fisheyeDistortion) properties. The default value of both radial distortion parameters is zero, resulting in a rectilinear projection. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)