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EOS focus Speed changes

Started Dec 10, 2014 | Discussions thread
WilbaW
WilbaW Forum Pro • Posts: 11,643
Re: EOS focus Speed changes

Doug Pardee wrote:

Focus speed in the EOS system is a function of the lens, not the camera.

Not entirely, the body does matter (e.g. see R2D2's post).

The camera determines what to focus on, measures the amount of misfocus, and communicates that misfocus amount to the lens, and the lens makes what it believes is the appropriate adjustment.

Then while the lens is moving the focus error is measured and the lens destination is updated accordingly, in a fast cycle. After the focus ring has decelerated to rest the error is measured once more. If the error is acceptable, focus is confirmed, otherwise the process repeats.

In the gray area between those is focus tracking of fast-moving objects. The camera needs to track the objects and predict where they will be at the time the shutter would be released, and the lens needs to be able to adjust focus fast enough to keep up.

It's the same fundamental process as described above, without the halt on confirmation.

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