Assymetrical AF (Left AF Problem) may be a general problem for the CAM3500FX AF module

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crosstype
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Assymetrical AF (Left AF Problem) may be a general problem for the CAM3500FX AF module
2 months ago

Since following surrephoto's threads I am very surprised that so many Nikon shooters choose to turn him down rather than giving a little bit of support or trust. I just cannot live to see him fighting alone.

The CAM3500FX AF module has been used in many Nikon camera bodies since the rise of Nikon in the digital era - the D3 resurrection, including the D3, D700, D3s, D4 etc, and most probably will also be featured in the upcoming D4s if the rumors are true. It is important to bring this up so that more consumers are aware of this potential problem and hence reduce the risk of losing money by ending up having to sell problematic units as used.

Don't get me wrong. I am a Nikon shooter (not a troll or hired to demote Nikon's products) and I enjoyed using my D4. For a starting amateur like me (who started taking random pictures a year ago), the D4 captured many amazing pictures for me, of which some were published in recognized magazines, became editor's choice at 500px, won prizes in contests etc, but most importantly, captured precious moments for my family. I bear the risk of having to sell my own unit cheap for posting this thread here, just to hope that Nikon could be aware of this issue and address it in future products. So please try to be nice to us.

I am doing a PhD in science in a decent university and I know what is called validated repeated experiments and statistical tests. Saving all those boring stuff, I am going to just upload some simple, adhoc and *informal* tests, just to illustrate and help you guys get an idea about what this problem is all about. Please do *NOT* ask for formal tests with more accurate equipment. There is no point unless I have access to Nikon's equipment at their repair centers. You may well question the flaws or accuracy of my tests (just as many of you attacked in the other threads) and I'm fine with that - in that case I bid you good luck with your Nikon gear and hope you enjoy it.

According to my experience with various camera bodies and lenses focusing on different subjects, I have listed several hypothesis with this left AF problem:

  1. This left AF problem is a general issue for all cameras using the CAM3500FX AF module;
  2. This problem is most famous on the Nikon D800 and D800E due to high resolution, but less known for the D3 and D700 due to low resolution;
  3. This problem is usually more pronounced on wide angle lenses, especially at the wide angle side on zoom lenses;
  4. This problem is "rarely" seen on normal or telephoto lenses, including the reference lens 50mm f1.4 D, which is used by Nikon to calibrate camera bodies sent in for service;
  5. This problem could occur on specific combination of a camera body and a lens, while the camera works just fine with another lens (of the same model) and the lens works just fine with another camera (of the same model);
  6. Some friends had Nikon fixed this problem, while some friends were frustrated by Nikon's repairs, and ended up having to sell the camera body.

To prove these "hypothesis" I would need scientific data and validation but life is too short for me for this and I would probably choose to suck it up and move on, instead of fighting against Nikon again, just like what I did for the focus shift problem caused by AF assist beam from Speedlights for no result. I did not bother sending in my camera body again because I expect they say "within spec" just as they stated before in previous cases.

I will start with a Nikon D4 with a 14-24mm f2.8G lens mounted. Below shows the focusing result of the leftmost and the rightmost AF point in the central row respectively. I hope this rules out the questions regarding the field curvature of the 14-24mm lens.

Nikon D4 + Nikon 14-24mm f2.8G @ 14mm f2.8

To eliminate the possibility of off-center defect of the 14-24mm lens, I further carried out tests on a Zeiss Distagon T* 15mm f2.8 ZF.2 lens. The manual focusing was done on prompt with the focus indicator in the view finder.

Nikon D4 + Zeiss Distagon T* 15mm f2.8 ZF.2 @ f2.8

To show that this is not a specific issue with the D4 (or D800) but also a general issue with previous products, I have done tests on a Nikon D3 camera body as well:

Nikon D3 + Zeiss Distagon T* 15mm f2.8 ZF.2 @ f2.8

I have not tested any D700 myself, but it's easy to google and get similar results:

http://hifivoice.wordpress.com/2012/09/02/d800-autofocus-the-grand-finale/

And for the D800 (D800E) I don't think it's hard to find similar complains because it's just too famous...

It would be extremely difficult to force Nikon to acknowledge this problem, just like Nikon denied to accept that the D600 had dust / oil issues. It is even more difficult because most Nikon shooters woudn't spend so much time carefully testing their camera bodies like we geeks do. When I said that the AF assist beam from the Speedlight would cause focus shift problems, most Nikon shooters did not believe in me, and Nikon of course denied to acknowledge it. This left AF issue may be buried into graveyards when the CAM3500FX AF module is finally dead, but it is likely to persist in the upcoming D4s (if the rumors are true).

 crosstype's gear list:crosstype's gear list
Sony RX1R Nikon D4 Nikon D4s Nikon AF-S Nikkor 200mm f/2G ED VR II Carl Zeiss Distagon T* 2,8/15
Nikon D3 Nikon D3S Nikon D4 Nikon D600 Nikon D700 Nikon D800 Nikon D800E
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