D800 Firmware Update Focus Improvement!

Started Apr 2, 2013 | Discussions thread
Robin Casady Forum Pro • Posts: 12,898
Re: Another example of misfocus

m_appeal wrote:

michaeladawson wrote:

m_appeal wrote:

It comes from View NX (Nikon software) and shows the point that was used for focusing. I certainly didn't draw the red square in. I'm using SINGLE point Af-c, so the camera should not switch focus to another point.

I assumed you didn't draw it in, but had to ask.  All I can say here is that if you use AF-C with 9 or more points the camera DEFINITELY will chose one of the adjacent focus points if it does not like the contrast under the user selected AF point.  You can easily test this yourself with a featureless wall with some high contract object close by.  If the AF spot is on the featureless wall and the high contrast object is underneath one of the 9, 21, or 51 points the focus will shift to that point.  Is this expected behavior.  Too many it is not.  But it is in fact how the camera AF system is designed.

Now you say you used SINGLE point AF-C.  I would agree with you that the focus point should not shift (although others debate this) in this case.  In fact, View NX is confirming this by showing the red AF box over the eyelid.  So  I would agree that your camera appears to be mis-focusing.

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Mike Dawson

That's exactly why I'm using single point and not 9 points. I don't know if I should send it in to Nikon to have a look at or if it's within spec. I don't think these results are acceptable though.

The alignment between where the AF point is and where the camera displays it may not be perfectly accurate. They have been known to be off in the past. You might want to try a few setups to see if you can identify exactly where the point is. It would be useful to know whether it is always offset by the same amount, or jumps around with different subjects. Use similar subject distances to keep from adding another variable to the test.

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Robin Casady
"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts."
— Bertrand Russell

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