Agree that the 300 f/2.8 was most likely Canon's sharpest lens when it arrived on the scene and I had a great experience with it but I ultimately traded it for a 500 f/4 ( to give to my son) due to focal length. I did not notice any significant loss of IQ and the 300 f/2.8 remains a popular choice for birds, especially flight shots. At the time, if I could have afforded to simply add the 500 and keep the 300 I would have for sure!