Very odd AF problem - Help

Philth

Senior Member
Before I start, all firmware is up to date on my D750 and my Tamron 24-70 G2.

This ONLY happens with my Tamron 24-70 G2, and it ONLY happens in AF-S Single

I'll half way depress the shutter release button to engage AF. Everything snaps to focus and I get the audible and visual indicator of a successful focus. Then, while the shutter release is still half depressed, the lens slowly rotates all the way to infinity focus. The visual indicator is still saying that the camera is focused on the subject.

Alternatively, if I throw my Nikkor 85mm f1/8 on, it works flawlessly with no problems. I sent the Tamron lens under warranty repair and they couldn't find anything, though they said they replaced everything in the lens that could cause this issue.

Anybody have any suggestions?
 

pforsell

Senior Member
Anybody have any suggestions?

No camera setting can cause that behavior and more importantly, if other lenses work normally it is not camera malfunction. So I believe we can be 100% sure the culprit is the lens. That kind of AF performance rises many questions about the accuracy, reliability and repeatability of the focusing, so I would not use it even with continuous AF.

Give them the benefit of the doubt and send it back again ASAP. If it cannot be fixed, my suggestions are: 1) get rid of it or 2) use it as a manual focus lens.

Just for the heck of it, I googled "tamron autofocus problem" and got 502,000 results. :p Sorry I cannot help more, I have never seen autofocus like that and never seen a Tamron lens in real life.
 

Philth

Senior Member
Lens is back at a Tamron as I speak. They have my D750 body so they can duplicate as well. Hopefully they’ll find it and/or send me a new lens.




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