The lens has a large amount of coma on the sides (mainly at 28mm) and is ok in the center at f2.8, stopped down to f4 it's much better than my 24-105 in the center and a close call on the edges and at f8 (possibly 5.6 - didn't check) mine is SHARP edge to edge right though the range - it's very good (some say better than 24-70mk1) at 70mm.
I have recently purchased a Canon 70D, upgrading from a 40D that had some issues after years of intensive use. I still have my Canon 17-85 EF-S IS lens however I feel that the lens is too soft and is not as sharp as I would like. I was wondering if upgrading to a 24-70 F/4L IS USM is wise choice? I found it on Amazon for roughly $1,000.
Reviews; Guides; Learn; Equipment; EF 24-70mm f/4L IS USM Macro, EF-S 35mm f/2.8 IS STM Macro, EF-S 55-250mm f/3.5-5.6 IS STM, EF It is not hard to purchase any Canon EF lens right now
The Canon EF 24-70mm f/4L IS USM ($1,499 list)($899.00 at Amazon) is a wide-to-short telephoto zoom lens for Canon cameras. It's noticeably smaller than the EF 24-70mm f/2.8L II USM, a lens that The F2 lens is the ideal choice for stopping motion at low light events and for blurring the background. If you don't need the f/2 aperture, you might find the EF 24-70mm f/2.8L II the better purchase choice. When the RF 28-70mm F2 Lens was first reviewed, most considered the Canon EF 24-70mm f/2.8L II USM Lens to be the primary alternative kIF0Em.