Hate to admit it, but I have the AF issue. Going to make a case with Nikon. Any advice?

Started Nov 4, 2012 | Discussions thread
Fayard
Regular MemberPosts: 127
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Re: Hate to admit it, but you are wrong.
In reply to M Powered, Nov 7, 2012

M Powered wrote:

Why do some people care so much about using test targets to test AF? Do they plan on using the camera to shoot test targets? Or take actual photos?

My subjects are people in various lighting conditions, time after time left / right AF points are not accurate. Thats a problem. I don't need to freaken test target to tell me the AF is not accurate.

When you shoot at a real subject, you have all these problems: the target and the light are not ideal and the subject is moving which might fool the autofocus (I don't even talk about people using speed which are too low and lead to camera shake or the movement of the subject).

These are problems that come on top of what I call AF alignement problems. When you want to test for AF alignement problems, you need to remove all the other potential problems.

I shoot with a Sony NEX7 also and never had any AF issues, do you "test target shooters" mean to tell me that the D800 AF is inferior to the Sony NEX7 AF?

The NEX 7 is not a reflex and does not have any Phase detect autofocus. It works with a contrast detect system, the same kind of system that you have with a D800 when you use Live View. These autofocus systems don't have alignement problems because everything is measured on the sensor.

So yes, in terms of accuracy, on a static subject, the Contrast Autofocus of the NEX 7 is likely to be better than the D800 Phase Detect system and even the D4 and the Canon 1Dx. But the Live View of those DSLR will be as accurate as the NEX 7.

On moving subject, the NEX 7 won't come close to the DSLR, the phase detect systems of these DSLR being far more reliable that contrast autofocus when it comes to moving targets.

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