← ToolBox / 安全快门速度

🏎️ Safe Shutter Speed Calculator

Find the slowest safe handheld shutter speed from focal length and crop factor, with stops of stabilisation taken into account.

焦距 mm

裁剪系数

防抖档数

安全快门（本页代码口径）：安全快门=1÷(焦距×裁剪系数)（s）；建议分母=焦距×裁剪系数；防抖后安全快门=1÷(焦距×裁剪系数×2^防抖档数)（s）。校验：三字段经输入守卫必填且须为合法数值，否则提示并中止。判据：无固定分级，裁剪系数等效放大焦距口径，防抖项按 2^档数倍乘入分母折算。

低于此速度易因手抖模糊，防抖可放宽。

📚 深度解析：安全快门计算

安全快门

50mm：安全快门 = 1/50s（分母≈焦距）；200mm 需 1/200s，焦距越长越易抖。

防抖放宽

5 档防抖：安全快门 = 1/(50×2^5) = 1/1600s 理论可更慢，实际保守用 1/（焦距×防抖档）折中 1/400s。

Item	Formula / Rule	Source / Standard
Rule of thumb	The safety shutter is about 1 ÷ equivalent focal length in seconds	ISO 12231:2012 Photography — Vocabulary
Pixel-density correction	High-resolution bodies warrant one extra stop, near 1 ÷ (2 × equivalent focal length)	ISO 12231:2012 Photography — Vocabulary
Stabilization credit	Body or lens stabilisation slows the shutter by its rated stops, measured to the CIPA standard	CIPA DC-011 Image stabilisation measurement