D800 Firmware Update Focus Improvement!

Started Apr 2, 2013 | Discussions thread
GroWeb
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Re: Again, I am using only one point for these
In reply to Daniel Lauring, Apr 5, 2013

Daniel Lauring wrote:

m_appeal wrote:

I'm not using 9, 21 or 51 points.

Never mind then.  

I haven't tried on such a difficult focus target.  I have used a tape measure and it hits the numbers under the focus square, but the tape measure has much more contrast than grain on wood.

In order to see if the new firmware changed this behaviour, I just did a test that I had done before, as follows.

I first set the camera in AF-S, centre point selected, and place the centre AF point over a bland, contrast-free point on the wall, close to, but definitely not overlapping a textured, contrasty picture frame. The camera hunts but never finds focus.

Then I set the camera in AF-C, single-point mode -- no dynamic area -- centre point selected, and place the centre AF point over the same bland, contrast-free point on the wall, close to, but definitely not overlapping the textured, contrasty picture frame. Unexpectedly, the camera does almost no hunting and snaps into focus on the picture frame, which is under the far side of a neighbouring AF point, a significant distance away from the centre point. When I move the centre focus point farther away from the contrasty picture frame, on the same bland wall, the camera hunts but never finds focus, just as in AF-S.

My conclusion from this is that the AF-C single-point mode will act like the 9-point dynamic area mode when it does not find a sufficiently contrasty target under the selected AF point. However, it appears that it does not go beyond the 9-point area in its search for contrast in the single-point mode.

As indicated above, this is not the behaviour I would have expected in AF-C single-point mode. It also raises some questions:

1) in this mode, how contrasty does the target under the chosen AF point need to be to ensure that the camera will not focus on something else nearby?

2) in 9-point dynamic area mode, if the camera does not find anything sufficiently contrasty under any of the nine selected points, does the camera look in a 21-point or larger area for a better target?

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