How to fine tune 24-70/2.8L backfocus on 50D?

Hi everyone,


I recently bought a 50D and I found my 24-70/2.8L back focuses on the camera body ONLYwithin the rangefrom24-35mm (focusing distance within 2m). Beyond 35mm the lens focuses perfectly.I guess if I micro adjust the lens to shift focus to the front it will affect the range from 35-70mm. So I don't know if there is anything that I can do to solve this problem except for sending the lens to Canon for calibration.


Thanks guys,


Benjamin