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Sigma SD1 and Sigma 18-35mm f/1.8 ART lens equivalent focal range?

Started Nov 7, 2016 | Discussions thread
atom14
atom14 Veteran Member • Posts: 3,301
Re: Sigma SD1 and Sigma 18-35mm f/1.8 ART lens equivalent focal range?

tylershoemakerix wrote:

... I'm wondering what the equivalent focal range (to 35mm) the 18-35 would be on the SD1 (1.5x crop factor) . . . Or because the lens was intended for APS sensors is the range actually a 18-35mm equivalent on smaller sensors and thus named so on the lens? Thanks for any input. I'm really looking forward to trying this lens on the SD1...

Yeah!  As stated, the markings are the "absolute" focal lengths. It is mostly a marketing shortcut to refer to lenses in terms of "equivalent FL in FF" and such. And how useful is it? You said you come from a cinematic background, and so were "FF" or "35mm" frames used there? How many digital users have ever used a 35mm camera, and what does it matter?

IMO, it's better to think of it in terms of "equivalent field of view", or FOV. Then you could more usefully ask "What is the equivalent FOV in FF?" (Perhaps??)

An image size of a (say) small bird will be the same whether you have F=300mm sitting on a FF camera, or whether you have an F=300mm lens on an APSC camera.

atom14('s 2c worth).

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