焦距

• Pinyin: jiāo jù
• Hanzi breakdown: 焦 = focal point (from 焦点); 距 = 足 (foot) + 巨 — distance

Meaning

Focal length. The distance between a lens and the point where light rays converge.

Technical term used in photography and optics. Determines the magnification and field of view of a lens. Longer focal length means more zoom and narrower field of view; shorter focal length means wider angle and less magnification.

Examples

1. 这款镜头的焦距是50毫米，非常适合拍人像。 This lens has a focal length of 50mm, which is perfect for portrait photography.
2. 调整焦距可以改变照片的景深效果。 Adjusting the focal length can change the depth of field effect in photos.
3. 长焦距镜头可以把远处的景物拉近。 A long focal length lens can bring distant subjects closer.

Usage Guide

Context: photography, optics, technology

Tone: neutral

Do Say

• 你这个镜头焦距是多少？(What's the focal length of your lens?)
• 焦距越长，背景虚化越明显。(The longer the focal length, the more pronounced the background blur.)

Don't Say

• 用'焦距'描述对焦清晰度 (Don't use 焦距 for focus sharpness — that's 对焦; 焦距 is specifically the lens focal length)

Origin & History

Composed of 焦 (focal point) + 距 (distance). A technical term from optics describing the focal distance.

Cultural Context

Generation: All ages

Social background: Photography enthusiasts