Legitimate Observation Re: AF-A?

Started Oct 19, 2012 | Questions thread
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Legitimate Observation Re: AF-A?
Oct 19, 2012


Keep the discussion focused (No pun intended)

Has anyone else noticed the behavior I laid out near the end of the previous thread?

Again, I invite you to try this if you have a D7000.

Set your cam to AF-A Single point.... 9 point.. etc. doesn't matter.

Set your center AF point as the AF point.

Choose a higher FL so that you know that focus will be critical.

I just went into a well lit large room and randomly picked targets to try this - small targets... big targets... dark ones..light ones... etc. In other words a typical test scenario.

What I observed that, in AF-A (True AF-A ... not AF-Auto Area)

For a huge number of various targets, the camera would not readjust AF once initial AF was acquired.... regardless how much I leaned towards the target, or moved away (simulating movement) .... or even moving the AF point completely away from the target and on to something well beyond the initial AF distance. Yet, when set to AF-C .. the camera continuously and ALWAYS makes adjustments for movement ... leaning in/out.. moving AF point away from intended target.

The whole purpose of AF-A is supposedly .... you have the best of both worlds. AF-S primarily.. and if the target moves beyond it's initial AF locked distance.. then AF-C kicks in. Well, I'm saying ... this is simply not the case 100% of the time... or anywhere near 100% of the time.

Then lenses I used for this demonstration was a 18-105VR, 70-300VR, and a 50 1.8D.

Of those, I observed that the 18-105 was least likely to readjust, and the 70-300VR most likely to readjust. The 50 1.8D was spotty, but less so than the 18-105. ALL lenses exhibited the crux of my argument.

My initial contention was that anyone having AF issues with the D7000 .. should avoid this mode until they have a thorough and complete understanding of what AF-A's limitations are.

Do I have a legitimate point? I think I do based on the above.

Again, please reply to this thread in the context of what I am saying/asking. I'm not interested in hearing about anyone with AF problems, or problems with Nikon... quality control...etc. etc.

Thanks and I'm looking forward to a healthy civil discussion.

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Nikon AF - One Shot ..... One Kill

Nikon D7000
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