I've been trying to figure this one out for a while with no clear answer so if anyone has a better idea please let me know. So my logical process goes something like this... variable aperture zooms actually have a constant diameter of the aperture (iris? can't remember the proper english name for it at the moment) and as the focal lenght is changed so does the ratio (the F number) With a constant aperture zoom the diameter has to grow with the increasing focal lenght so that the ratio can stay the same but here's where I bump into a wall... if there's "room" for a larger diameter on the tele end of the range, why isn't it used on the wide end? Essentially what you'd get from this is a variable aperture zoom but with a larger F number (lets say a F1-2.8 from a 2.8 fixed compared to the usual 3.5-5.6 or whatever) or am I missing something? help?!