Exactly what is wrong remains confidential, and what they’re going to do about it remains unknown, but Tamron felt the need to acknowledge an issue with the well-liked 28-75 f/2.8 lens for Sony E-mount. The release quietly popped up on the web two days ago.
The 11-20mm of the same series
The lens previously suffered an autofocus issue that particularly bedeviled video shooters using long focus pulls. That was addressed with a firmware revision released a little more than a week ago.
The new problem appears to affect only about 450 lenses with specified serial number ranges, suggesting a part-related manufacturing problem.