News came out from Canon that they "Will Exhibit Prototypes Of Two New Telephoto Lenses Under Development,"EF500mm F4L IS II USM" "EF600mm F4L IS II USM" At Photokina, 2010"
LAKE SUCCESS, N.Y., August 27, 2010 – "Canon Inc. today announced the development of two new telephoto lenses, EF500mm F4L IS II USM and EF600mm F4L IS II USM for use with all EOS single-lens reflex cameras. Canon Inc. will exhibit prototypes of these new lenses at Photokina, being held in the city of Cologne, Germany from September 21 to 26.
Both EF500mm f/4L IS II USM and EF600mm f/4L IS II USM have been developed as luxury lenses having high-performance Image Stabilization. These lenses are designed to help produce high-quality images with high levels of resolution and contrast as well as be lightweight. They will utilize particular optical material such as fluorite lens elements to help minimize chromatic aberration and eliminate color blurring around the edges of the subject.
These two lenses will be the successors of the EF500mm F4L IS USM (Launched in July, 1999) and EF600mm F4L IS USM (Launched in September, 1999) which were highly regarded by professional users. The goals for the development of these two new lenses are high-quality images with higher levels of resolution and contrast at the largest aperture, enhanced dust and water resistance, sufficient for use under challenging conditions such as press photography, sports photography and nature photography.
Canon plans to continue to respond to various needs of professionals and advanced amateurs and enrich the photographic experience with single-lens reflex cameras by expanding its EF lens lineup and seeking improvements in performance."
This press release came direct from Canon's site.