Tamron 70-300 focus issues and wrong f/ number reading

Hello all,

I don´t if someone could help me with a problem I have with my Tamron 70-300 f/4-5.6 DI VC USD, everytime I turn the camera on, the AF motor doesn´t works and the f/ number jumps from f/1 down to f/90 (...) this problems go if I move the focus ring to half, but appear again after some minutes, it´s very frustrating to be planespotting and suddendly the lens don´t work.

Regards, Lien Savo.

I have a similar issue with the same lens, although it happens a bit differently. Sometimes between the shots, when I'm not taking any pictures, but I leave the camera on (Nikon D7200), the AF suddenly locks up and the aperture goes to f/90. The issue goes away when I re-focus on a closer subject and most of the time it's not happening again in the same day, but it's still a bit annoying. Fortunately it never happened to me when I was about to shoot something unexpected, so no pics lost.

I have no idea why this is happening, otherwise the lens works just fine.

That´s just the problem I have! But it happens quite more often to me, how many years does your lenses have?

Honestly, I don't know. I bought it used in March 2019 and never really give it any thought about its age. Considering that it was visually in near perfect condition back then, I'd say that it's maybe 2-3 years old, but could just as well be older - I don't have have any documentation of its first purchase so it's nothing more than a guessing game.