Tamron Zoom Telephoto AF 70-300mm f/4.0-5.6 LD Macro Autofocus Lens for Canon EOS "80 200 stuck focus" Questions

my switch gets stuck on Manual focus and I can't get it to switch up to AF. It's a lens from the early 1990's... try to turn front barrel lens while switch it.

...80 job. I am facing the same problem. The only way to avoid it is to use it at the maximum aperture between 180-300, thats 5.6. I have the same thing. When you press the aperture control button (only ...