I accidentally saw Nikon 17-35mm f/2.8 lens and noted that it is rather large for its focal length. Here's the first review of this lens search offered - looks like it's 107 millimeters long. Given its focal length of up to 35 millimeters I would expect it to be more like a pancake lens but 107 millimeters is very far from pancake lens.
I guess there're some design reasons for that.
Why is this lens so long given it's rather short focal lengths?