I would expect 14-24 F/2.8 vs 16-35 F/4....
It is an interesting move. Maybe Canon sees the market in cheaper and more broadly used L lenses? Interesting why they are going F/4 IS lately. Probably it is something that will give them more sales, I guess.
14-24 would likely mean bulb element and won't natively take filters...... Aka royal pain in the buttox. Been waiting for a super optic lens that takes filters. This is it!
But it shows the amount of astigmatism present in the bokeh. Generally, when the dash lines are near the straight lines, it means the lens will have pleasing bokeh. They're correlated, it shows you how well the lens handles out of focus elements.





