AF compatible at f/8

Started Nov 4, 2013 | Questions thread
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philippe trougouboff
Forum MemberPosts: 98Gear list
Re: AF compatible at f/8
In reply to peevee1, Nov 10, 2013

peevee1 wrote:

dad_of_four wrote:

philippe trougouboff wrote:

Can someone explains the meaning of "The center focus point is compatible with AF at f/8" ? Why f/8 only (and not f/5.6, f/11, etc)?

It means a MINIMUM aperture of f/8. Certainly a larger aperture f/5.6, f/4 will work.

At smaller apertures like f/11, there simply is not enough light passing through the lens/aperture for the AF to operate

There might be enough light if the subject is well lighted, but there will not be enough angle difference in the light - light paths for the light coming through the periphery of aperture will be too close to light path of the light coming through the middle of aperture for the PDAF sensors to distinguish between the two.

I'm impressed by the knowledge, thanks for sharing it. 

 philippe trougouboff's gear list:philippe trougouboff's gear list
Nikon D7100 Nikon AF-S Micro-Nikkor 60mm f/2.8G ED Nikon AF-S Nikkor 70-300mm f/4.5-5.6G VR Tamron SP AF 17-50mm F/2.8 XR Di II VC LD Aspherical (IF) onOne Perfect Photo Suite +2 more
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