Rodinal wrote in post #8135181
If Canon made it that wide, it's most likely because it needs to be...
I am not so sure if it is really necessary.
Why I think this? It is because I used to have Canon EF-s 10-22 and Sigma 10-20. They both have wide end of 10mm, 77mm front thread. The Sigma hood is so low profile it is just barely wider than the lens itself. The Canon one, as you know, same hood as 17-40L, which is just as much of a salad plate. this make me think that Canon could have done much better job for the hoods design
Actually, Canon hood are sometime (or often time) under design even it is so big. I have been using 17-55IS hood, which is designed to have FOV of 27mm, on 24-105L on 5D. No additional vignetting introduced.