The 24-70 f/4L IS's image sharpness is difficult to summarize in a single sentence or two. Therefore, I'm going to pull from Bryan's review for a detailed description: With a wide open f/4 aperture: At 24mm, the Canon EF 24-70mm f/4L IS USM Lens is very sharp in the center with good sharpness extending to the periphery of the full frame image
The new EF 24-70mm f/2.8L II USM professional zoom lens is an update to the popular EF 24-70mm f/2.8L USM, while the new EF 24mm f/2.8 IS USM and EF 28mm f/2.8 IS USM are the world's first 1 wide-angle prime lenses to feature optical Image Stabilizer (IS) technology. All three provide the highest levels of performance for modern digital
As I said the new lens is already out. the 24-70 f/4 IS. Supposedly Canon is preparing to switch over the kits using the 24-70 f/4 IS. And the 24-105 got kitted up in so many 5D3 and 6D packages that the market got totally swamped by split kit lenses that are for all intents and purposes, new. And the Tamron 24-70 VC came out as well.