I have a Canon EOS T3i 600D. When I use a Canon-branded lens (18-55mm), the camera works well. When I change to the Sigma macro 18-250mm and turn the camera on, I can hear a ringing noise, like ...
My 16-85 VR is doing some weird noise during focus, manual or auto. It's like an hiss. I asked in a local shop and they said it can be some microdust inside the lens. But I'm a little worried it can ...