Sigma 17-50 autofocus squealing/whining

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bkjones88
bkjones88 Forum Member • Posts: 96
Sigma 17-50 autofocus squealing/whining

I'm having autofocus issues with my Sigma 17-50 (paired with my D3400) which seem to be getting worse. Specifically, the AF mechanism makes a horrible squealing/whining at times and will barely move. The problem kind of comes and goes, and initially would only occur at the 17mm end. However, it's now doing it occasionally when zoomed further. As you can see and hear in the videos below, it only seems to make the noise when focusing from near to far, and not from far to near. The focus ring is not being physically impeded at all (externally at least) and it always turns fine manually.

Not only does this prevent the lens from autofocusing correctly when it occurs, but I'm concerned that it's a sign AF motor is about to go kaput. Fortunately the lens is new and is still under warranty. I plan on contacting Sigma, and expect them to take care of the problem. However, I also wanted to see if anyone else here has had similar issues.

When it's working, it focuses quickly and accurately (with the exception of some front focusing at 17mm at infinity).

Also, what have people's experiences been with Sigma USA warranty repairs as far as turn around time is concerned? I'm leaving for a trip to Ireland in about 2 months and would like to take this lens with me.

First video with lens cap off, focusing on an object a few feet away. Second video with lens cap on.

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 bkjones88's gear list:bkjones88's gear list
Nikon D3400 Sigma 17-50mm F2.8 EX DC OS HSM Tokina 11-20mm F2.8 Nikon AF-P 18-55mm F3.5-5.6G VR Nikon AF-P 70-300mm F4.5-6.3G
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