Why F/6.3, when the same lens (via adapter) is F/5.6 on DSLR?

Started 6 months ago | Discussions thread
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007peter
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Why F/6.3, when the same lens (via adapter) is F/5.6 on DSLR?
6 months ago

DSLR:

  • Canon 55-250mm IS STM F/4 ~ F/5.6

Yet the same lens for Mirrorless M is

  • Canon 55-250mm IS STM F/4.5 ~ F/6.3

its the same with Sony: its 55-250mm lens for Alpha dslr = 5.6, but mirrorless NEX = 6.3.  Is there something about mirrorless that rub 1/3 stop of light???

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Nikon D3100 Canon EOS M Canon EF-M 22mm f/2 STM Nikon AF-S Nikkor 35mm f/1.8G
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