Canon is Still Working on EF 24-70mm f/2.8L IS USM Lens
The rumored Canon EF 24-70mm f/2.8L IS USM lens is currently in development. According to CR, Canon is still working on this lens. The release date of this lens is currently unknown, could be announced in late 2017 to 2018.
When EF 24-70mm f/2.8L II USM lens in development, there were prototypes with IS being tested alongside the non-IS version that was eventually released. The reason is that the weight and size is large that makes some sense once you consider the target market, which is generally event photographers that have to carry and use the lens for 12 hours or more on some occasions.
So Canon is still actively working on this IS version lens, to find ways to reduce weight and size.
via:CR
