With the "angle of view" on the 12-24 being 122 degrees at the wide end(Sigma stats) compared to 106 degrees (if I remember correctly) on the 10-20, wouldn't that make the 12-24 a "wider" wide angle lens even though it gives up 2mm? Or am I thinking about this incorrectly? Which one actually takes in more territory? Would the 12-24 also be inherently sharper and have less distortion? Ignore price for a moment on these - I realize the 12-24 is more expensive. Thanks in advance for your thoughts and expertise!