I have an EF-mount Tamron 70-300mm f4-5.6 lens that seems to have developed a problem. On all focal lengths from 70mm to approx. 200mm, the lens works flawlessly. When the zoom ring goes above 200mm, the lens fails to work at any aperture narrower than f5.6.
If I set the aperture to f6.3 or narrower, pressing the DOF preview button does not stop the aperture down. I've tried this lens on both an EOS 30D and a brand new EOS 600D, both cameras hang. The 30D gives me
Error 99 and the 600D tells me that
Communication between the camera and lens is faulty. Clean the lens contacts.
I have tried cleaning the contacts on both the lens and the 30D, and it didn't help. Does anyone know what is up with the lens? Is there an easy (read cheap) fix or will I have to take the lens to Tamron and get it serviced?