Re: Used Sigma UC Zoom 70-210mm focus ring very stiff/grinding and autofocus motor getting stuck: Third Party Lens Talk Forum: Digital Photography Review
Stiff focusing ring on a Biotar 58/2...? No problem!!!
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How to losen a sticky focus ring without damaging the camera | Photrio.com Photography Forums
Tamron SP 90mm f/2.8 macro, manual focus adaptall - stiff aperture ring?: Fujifilm X System / SLR Talk Forum: Digital Photography Review