Compared with its predecessor, the EF500mm f/4L IS II USM features a completely redesigned optics to provide better image quality and significant weight reduction. The lens is 680g lighter due to the active use of magnesium alloy and titanium. Higher level of image quality has been achieved by the new optics which features two fluorite lens elements.
The Image stabilizer's shutter speed equivalent has been increased from around two times faster to approximately four times faster. The IS Mode 2 has been improved and the lenses have been equipped with an all new IS Mode 3 which only activate the IS mechanism when during shutter press. These features, coupled with other improvements such as better dust- and waterproofing make this ultra high-performance lens that combines superb ease of use with excellent durability made for the digital age.