chromophore said:Zoom ratios are exactly that: a lens like a 70-200mm has a zoom ratio of approximately 200/70 = 2.85714x at infinity focus, and the general formula is zoom ratio = (longest focal length)/(shortest focal length); therefore, a lens with only one focal length, say an 85mm prime, has a zoom ratio of 85/85 = 1x.
Technically that is correct, but what people want to know is how much closer something will appear when using this lens compared to a "standard" lens. For FF a "standard" lens would be 43mm (diagonal of the sensor size), so a 70-200 would be a 1.6-4.6x (IMHO).
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