autofocus problems

Hi all, This Friday i received my used Sigma 150-500, when i first screwed it on my D7100 I was all that I finally for my first telephoto. But, my happiness was short lived because I noticed that the AF-C and focus area symbols were flickering on the top screen and the lens wasn’t focusing at...

Hi! I'm suddenly experiencing an auto-focusing issue with my Tamron 28-300mm Pzd VC f3.5-5.6 lens for full frame sensor cameras (Canon mount). I've never encountered this before with this or any other lens. And there was no gradual deterioration: from one day to the next, autofocus just started...