If shooting at f/22, is a fast 1.8 lens still considered fast?

Started Apr 17, 2011 | Discussions thread
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edwardaneal
edwardaneal Veteran Member • Posts: 9,101
Re: And Wikipedia is wrong in this regard

you are acting as if opening up the apreture only effects the brightnes in some outer band outside some mythical "f/5.6 ring" as you call it and your theory assumes that the phase detect sensors cant see the area outside this "ring"

but as you well know opening up the apreture increases the brightness equally across the entire frame.

when the projected image is brighter it is easier to detect contrast and easier for the AF system to do its job. And yes, even phase detect AF systems rely on being able to see contrast to focus properly

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My kit - D200, 10.5mm f/2.8D, 35mm f/1.8G, 50mm f/1.4G & 70-300VR
SB800, SB600 and other misc lighting equipment

Lenses worth mentioning owned and sold– 12-24 f/4, 17-55 f/2.8, 35-70 f/2.8, 80-200 f/2.8, 20mm f/2.8, 35mm f/2, 50mm f/1.8, 50mm f/1.4D, 60mm f/2.8D, 85mm f/1.8, 105mm f/2D-DC, 180mm f/2.8, 300mm f/4D-ED

 edwardaneal's gear list:edwardaneal's gear list
Sony Alpha NEX-7 Sigma 60mm F2.8 DN Art Carl Zeiss Touit 1.8/32
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