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
olyflyer Forum Pro • Posts: 24,915
Re: left/right AF asymmetry

Leo360 wrote:

olyflyer wrote:

Careful selection of target is important, just like good light and steady tripod, as well as mirror lock and in fact also a remote trigger to eliminate "AF error" caused by camera shake.

Nobody disputes the importance of a proper target. But, please, enlighten me regarding the following dilemma. If the target is left/right symmetrical, light is uniform, focal plane is parallel to the target plane then why on Earth left-AF sensor perform differently from corresponding right-AF sensor?


Don't ask me, ask Nikon. Never the less, page 100 is clear about that, since one example is exactly the target you are describing, like a bar code, which some times is a good target other times it is not and it is always good target for the center, cross type sensor. As a matter of fact, I think a daily newspaper is some times a much better target than any chart because of the small prints give you good detail and high contrast to focus on. There is no "uniform light" for me. There is good light or bad light. bad light is for example low energy florescent light, good light is halogen bulbs, or something not flickering like the florescent bulbs, which flickers with the mains frequency. On a bad target the results may be random. Also, if you feel the results are consistent, turn the camera upside down so that left becomes right and check again.

Never the less, the type of the target is important. Also, CDAF and PDAF are not the same, CDAF is more accurate but slower. I am not going to argue this, no doubt there may be cameras with serious problems, but in my opinion spending a great deal of time on AF testing is pointless. That's not what I bought a camera for. If I am happy with my images then fine, I can live with occasional misses. I have some sour experience with Olympus and Olympus never really sorted out the AF issues for their E-3, and as a result, the hit rate with any of the 11 AF points, but mostly the edges, was down to 50-70% which is unacceptable.

I can not say there are no cameras with AF problems, of course there are, but I can definitely say that most of the people testing their cameras for AF are doing it totally wrong, including the OP of this thread. This is what creates all the hysteria around the "left AF issue" and I am by now pretty convinced that these erroneous tests and conclusions created the hysteria. There is so much confusion on the internet about how to test AF that it is simply unbelievable. I thing 99% of those people would be happier without internet or without all these tests. They should just take images and ask themselves "Am I happy with my images?" and if the answer is no they should spend time reading a book or attending a photography course of some kind. Testing and looking for errors will just make you want to test more and look for more errors and eventually you will find some and then it is up to you to get convinced one way or the other, especially if you don't really know what you are doing. In most tests the largest error is made by the tester, not the camera or the lens.

Yes, fanboys deny the existence of any errors but that does not mean that anyone claiming an "issue" is right about a certain problem.

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