# fStop The physical camera aperture simulated by SceneKit for depth-of-field effects. Animatable. ``` var fStop: CGFloat { get set } ``` ## Discussion F-stop numbers describe the light-gathering area of a physical camera’s imaging system, and are typically expressed as the denominator of a ratio including the camera’s focal length ƒ, such as ƒ/2 or ƒ/5.6. A larger denominator indicates a smaller aperture, allowing less light to pass from the camera’s lens through to the imaging plane (sensor or film), and a smaller denominator indicates a larger aperture that lets more light through. SceneKit uses aperture measurements to simulate depth-of-field blur effects (also called *bokeh*) approximating those produced by a physical camera. A larger [`fStop`](/documentation/SceneKit/SCNCamera/fStop) number (or aperture denominator) causes most of the scene to appear in focus, with extremely close or far depths showing slight blurring; a smaller number results in only a narrow range of depths appearing in focus, and a more pronounced blur effect for the rest of the scene. The default [`fStop`](/documentation/SceneKit/SCNCamera/fStop) value is `5.6`. You can animate changes to this property’s value. See [Animating SceneKit Content](/documentation/SceneKit/animating-scenekit-content). --- 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)