Caution ! Dynamic AF versus single point AF... !

Started Jan 13, 2013 | Discussions thread
rubank
Contributing MemberPosts: 618Gear list
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Re: Yes, 9 or nothing
In reply to michaeladawson, Jan 16, 2013

michaeladawson wrote:

SteveL54 wrote:

Mako2011 wrote:

SteveL54 wrote:

Several folks here seem to imply from the manual that the camera must acquire and lock onto whatever is under the selected AF bracket. There are conditions that it just can't. The manual just does not say what happens in this case either.

From testing (dynamic AF-Area mode), when it can't find contrast under the primary point, it may lock onto contrast in an immediately adjacent array (the 8 surrounding the primary). If no contrast is in those 9...then it just hunts and will not lock onto anything in the outlying array FOV's regardless of how strong a contrast.

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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)

At least that's the way my D300 tests. But my point is that some people seem to interpret this as not following the manual -- even though the manual really says nothing about initial acquistion rules.

Steve

You are right Steve. People are inferring things that are not stated in the manual. So it would be accurate to say the manual is not wrong. Technically speaking there is no evidence that Nikon is not following the manual.

However, I think it is a reasonable inferrence to make. Nikon goes to the trouble to state how the tracking works. It seems like a major omission to not also add some explanation of what happens in dynamic AF mode when there is not suitable contrast under the selected AF point. I would think this simple inclusion would save them a lot of money in tech support dealing with reports of faulty AF.

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Mike Dawson

The problem is that even if there is enough contrast under the chosen AF point to lock focus the D800 sometimes shifts focus to an adjacent point with higher contrast! By "enough" contrast I mean that if you set the camera to S it will not hesitate to lock focus on the same spot.

According to the manual it should lock focus under the primary point and use the adjacent points if the subject momentarily leaves the area under the chosen point.

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