← ToolBox / 微距放大率

📷 Macro Magnification Calculator

Calculate magnification ratio from focal length and extension tube length, and see the resulting field of view and exposure loss.

焦距 mm

物距 mm

画幅高 mm

微距放大率：放大率 m = 焦距 f ÷ (物距 s − f)（×）；联动量：像高 = m × 画幅高（mm）。校验：焦距、物距、画幅高三项必填守卫，物距 s 作为分母不得为 0。判据：无固定分级，物距越接近焦距放大率越大（s 趋近 f 时急剧增大），放大率即像高与画幅之比。

m=1 为等倍微距，标本与像等大。

📚 深度解析：微距放大率计算

放大率

物高 24mm 在传感器成像 24mm（APS-C 高）：放大率 M = 1.0×（1:1 真微距）；若像高 12mm 则 M=0.5×。

最小物体

M=1.0、传感器高 24mm：可拍最大物体 = 24mm 充满画面；拍更小需更高放大或后期裁切。

Item	Formula / Rule	Source / Standard
Magnification	m = f ÷ (s − f) with s the subject distance; at 1:1 the distance equals 2f	Kingslake, Optics in Photography, SPIE Press, 1992
Effective aperture	N_eff = N × (1 + m), so at 1:1 the exposure drops two stops	ISO 12231:2012 Photography — Vocabulary
Depth squeeze	Depth of field shrinks with m² and often falls to about a millimetre at 1:1	Kingslake, Optics in Photography, SPIE Press, 1992