>>4109996This might give you an idea (8-16 f/2.8 left, 10-24 f/4 right)
At the very least, the maximum aperture - and thus the overall diameter - yould have to increase 1.4-fold to reach a constant 2.8 f-number. This is harder to do in the 10-24 in fact, as it goes up all the way to 24 mm focal length, whereas the 8-16 stops at 2/3 of that. A constant 10-24 zoom would thus have to be wider than the 8-16 by a third