Thanks oscaroo for the comparison.
Good job, technically, and helpful labels / explanation.
I have a Canon 7D which I love (and Canon 350D... but let's not go there... lol... my trusty 1st DSLR).
Amongst my arsenal of lenses, I also have the Canon 15-85mm (love as a walk around) and the Sigma 10-20mm (great UWA).
Your comparisons are helpful. I do like the Sigma UWAs, and interesting you can use it on the 6D.
I have never ever liked the fisheye effect, so again your post makes me glad I have and am sticking with the rectangular lens versions.
Cheers... nice image! Where was this photo taken?
I live in Adelaide, South Australia.
Paul