FE 24-70mm F4 OSS Here Today .. Gone Today! Locked

Started Mar 4, 2014 | Discussions thread
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Miki Nemeth
Miki Nemeth Senior Member • Posts: 1,284
Henry says that F4 on FF is F2.8 on APS-C and F2.0 on m43

blue_skies wrote:

Remember that F4 on FF is F2.8 on APS-C and F2.0 on m43?

Hi Henry,

I have learned so much from You, here on the pages of this excellent forum. This point I do not understand completely. I had the impression that F-number is the same on any camera systems, just like focal-length. Do you mean that the DoF of F4 on a FF camera is the same as the DoF of F2 on a m43? Does this mean that a FF camera with F4 can auto-focus at the same speed as a m4/3 camera with F2?

Another related question: If I change the A7 to APS-C mode the effects/usability of F4 changes down to F5.6?

Thank You for the help, Miki

 Miki Nemeth's gear list:Miki Nemeth's gear list
Sony a5100 Sony a9 Canon TS-E 17mm f/4L Sony E 16-50mm F3.5-5.6 PZ OSS Zeiss Batis 25mm F2 +15 more
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