The equipment is a Canon 80D body with a Tamron 18-200mm F3.5-6.3 lens. Sometimes while shooting, before the lens focuses the image seems to "drop" a little in the lens. I know it's not the best lens. But what could be causing this? Is it just a crappy lens? Can it be fixed? Is it damaged? I've only noticed this happen in auto focus and doesn't seem to effect the image quality.