7D F8 autofocus

Started Oct 22, 2012 | Discussions thread
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Michael Eckstein Senior Member • Posts: 2,159
Re: Liveview Auto Focus

riknash wrote:

Michael Eckstein wrote:

This shot was taken with 7D and 400L ƒ5.6 and Canon 2X with liveview auto focus.

Nice photo but with Liveview, it is using a completely different method to achieve focus. It uses the sensor in contrast detect to determine very accurate focus. That has nothing to do with phase detect AF at f/8 since it is simply a matter of enough contrast in the area of the focus site on the sensor that determines absolute focus. I suspect the insect wasn't moving very fast, if at all since contrast detect is a much slower process as it must constantly sample the light at the focus site and compare with previous samples. Phase detect on the other hand provides very fast focus and can be programmed to 'follow' a moving subject using a predictive algorithm since slight variances are instantly measurable and can be compensated more directly.

I am well aware of how live view  AF differs from normal AF. BTW the image was taken at ƒ11 and I was impressed how quickly AF was achieved. Certainly much better than no AF!

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