D7100 - setting focus points

Started Jun 12, 2013 | Discussions
Skiies
Regular MemberPosts: 153
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D7100 - setting focus points
Jun 12, 2013

In my autofocus menu , a6, I only have the choice of 51 points or 11. Is this correct??

Nikon D7100
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mosswings
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Re: D7100 - setting focus points
In reply to Skiies, Jun 12, 2013

Skiies wrote:

In my autofocus menu , a6, I only have the choice of 51 points or 11. Is this correct??

Don't confuse the number of af points that you can manually select as the "targeting" point with the number of AF points the AF system uses to maintain focus (AF Area Mode, dynamic-area option, adjusted using the pushbutton on the left of the lens and the control wheels)

Option a6 is basically a convenience setting that speeds up moving to the desired targeting point by limiting the number of points accessible to 11 from the full 51.  It reduces the number of targeting points to those available on earlier Nikons, like the D90 and D5100.  However, the targeting points you select will be aided by the number of points you select in your AF Area Mode.  In single point AF, only the selected targeting point controls focusing. In dynamic area AF, the immediately surrounding 9 or 21 points ( basically, one or two rings of focus points around the selected point ) - or the full 51 point array - will contribute to maintaining focus at the selected targeting point. In 3D-tracking, the focus point will actually move to track the subject given certain conditions.  In Auto-area AF, the camera will pick what it thinks is the subject.

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Skiies
Regular MemberPosts: 153
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Re: D7100 - setting focus points
In reply to mosswings, Jun 12, 2013

Thanks for the reply! So if I am taking shots of a dog running towards me should I use single point AF or 9 or 51? Would it make much of a difference? I have tried 3d tracking but I don't seem to be able to get on with it.

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mosswings
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Re: D7100 - setting focus points
In reply to Skiies, Jun 12, 2013

Skiies wrote:

Thanks for the reply! So if I am taking shots of a dog running towards me should I use single point AF or 9 or 51? Would it make much of a difference? I have tried 3d tracking but I don't seem to be able to get on with it.

3D tracking is a mixed bag.  It's memorizing the colors of what's under the focus point, then attempting to match the color pattern as it moves from focus point to focus point.  That's a lot of processing going  on, and it isn't quick.  It works better for focus-and-recompose, but only if there is a clear color difference between subject and background.  I don't use it.

The 9/21/51 point modes for dynamic AF are used when: 9 pt - the object is moving slowly and predictably; 21 pt - the object is moving more quickly and somewhat erratically; 51 point - the subject is moving very quickly and erratically.  However, the more points used, the greater the computational load, so you should use the minimum number of points that you can.

For your running dog photos, it's fairly easy to keep the subject centered over your desired focus point, so 9 or 21 point will do just fine.

 mosswings's gear list:mosswings's gear list
Olympus XZ-1 Nikon D90 Nikon D7100 Nikon AF-S DX Nikkor 18-105mm f/3.5-5.6G ED VR Nikon AF-S Nikkor 70-300mm f/4.5-5.6G VR +1 more
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