Old Sigma Lenses Close Distance Auto-focus on Canon 6D

<p>Yesterday when I was in a garden, I noticed that the auto-focus of my old Sigma 105 micro lenses was not working. I thought I need to contact Sigma service department to find out whether they could fix the problem or not (they couldn't fix the same problem on my old 17-35mm lenses). Today, I check the lenses again and find the auto-focus problem only occurs in a close distance inside of their close focus distance specfication. The auto-focus works sometimes, but have a difficulty of performance consistently in a close distance. And my another old 70-200mm Sigma lesnes exhibits the same behaviour while their latest 24-35mm and 20mm lesnes don't have this behaviour. I am wondering other people also experience the problem or not. My 6D has the latest firmware on. </p>

<p>You're lucky it works at all. My old Sigmas give an error if I try to focus or stop down. I can shoot if the lens is wide open and in MF mode. When it first happened Sigma told me they no longer support my lenses with ROM updates. If you use them with an old camera, they work fine (worked with my Elan 7 but not 6D).</p>