The new Canon EF 100-400mm f/4.5-5.6L IS II lens is scheduled to start shipping this week. It is a long-awaited replacement for the old 100-400mm L model that has been around for 16 years now. The first copies of the new model should ship out on Friday, Dec. 12. Check it out here at B&H Photo.
I have the older version. I forgot when I got it but it is more than 6 years. I do not think it worth changing to the new version. Maybe somebody does it and could tell use how much a difference it makes, whether it is worth the extra money because to sell the old one? Well ?