Thank you all for your comments. I use the AI-Servo mode all the time because till now I only found advantages. It is my standart since the mid 90' because I find it more flexible. I asked that question also by email to the german canon professional service and they called me back (that's good service) and told me that maybe the frequency of the af must be adjusted or there is dirt in the USM. Or at least, if the lens got a knock or dropped down that will indicate a dying USM. And the owner who wanted to sell me the lens said it dropped down once. So I will return the lens and search for another one.
Thomas * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
