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As an adjunct to the Tangents blog, the intention with this forum is to answer any questions, and allow a diverse discussion of topics related photography. With that, see it as an open invitation to just climb in and start threads and to respond to any threads.
it is my understanding that aperture size is determined by focal length divided by Fstop, which means for example a 70-200 f/2.8 lens set at 2.8 will have a larger diaphragm/aperture at 200mm than at 70mm and allow in the same amount of light, this can explain why a typical kit lens has a variable aperture of 3.5-5.6 b/c when zoomed in the aperture cant expand larger to accumulate equal amount of light from its zoomed out position.
If this is so than why isnt a 70-200 f/2.8 a 1.8 - 2.8 lens since at 70mm its aperture is not its widest at 2.8?
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