f/8-compatible body?

Started Dec 20, 2012 | Discussions thread
mrwilkins
Forum MemberPosts: 70
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Re: f/8-compatible body?
In reply to as1mov, Dec 20, 2012

I can explain for you what it means.

Nikon system cameras autofocus with the lens wide open.  This both improves focus accuracy because it increases how much the contrast varies with small differences in focus point, and also it makes the image in the viewfinder as bright as possible when you're looking through the camera.

When you press the shutter, the mirror flips up, the iris closes to the aperture you've selected, and the shutter opens.

Different camera bodies require different minimum amounts of light to autofocus.  The better ones can do so with less light.  An "f/8 compatible body" is one that is able to autofocus even when "wide open" on the lens is f/8 as opposed to a more typical f/1.4-f/5.6.

When you mount a lens with a teleconverter, you're reducing the minimum effective aperture of the lens, and so less light reaches the AF sensor.  That's why it specifies that you need a camera model that is able to focus at f/8 to use that particular lens/teleconverter combination with AF.

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