Eye relief意思

"Eye relief" is a term commonly used in the context of optical devices such as telescopes, binoculars, and firearms. It refers to the distance from the eyepiece or objective lens at which the user's eye must be positioned to obtain a full, comfortable, and undistorted view.

In the case of telescopes and binoculars, eye relief is important for comfortable viewing, especially for people who wear glasses. If the eye relief is too short, the user may experience vignetting (darkening of the image at the edges) or may not be able to see the entire field of view, which can be frustrating and reduce the overall viewing experience.

For firearms, eye relief is particularly critical for the use of telescopic sights or optics. It is the distance from the back of the scope to the shooter's eye at which the image is correctly focused and the shooter can see the full field of view. If the shooter's eye is too close to the scope, they may experience "scope bite," which is when the scope's eyepiece hits the shooter's brow or eye socket when the rifle recoils. Conversely, if the eye is too far away from the scope, the image may become distorted or the shooter may not be able to see the full reticle, making accurate shooting difficult.

In summary, eye relief is the distance at which the user's eye should be positioned to see the full, clear, and undistorted image through an optical device.