I'm looking for a wide aperture wide angle lens to use with my 5D III body. I'm planning to use this lens for reportage shots in low light conditions.
After doing some research, I'm trying to decide between Canon 35mm f/1.4 and Sigma 35mm f/1.4.
If you trust the tests, Sigma seems to perform better than Canon in the fair light.
Some time ago, I've tested Zeiss 100mm f/2 at f/2 vs Canon 50mm f/1.4 at f/1.4 in low light conditions, and I felt that the Zeiss actually performed better. I think this is because of the quality of the glass used in those lenses. That's why, despite that both lenses have f/1.4, I'm really worried if Sigma is going to be at least as good as Canon in low light.
Did anyone compare those those two lenses in low light conditions? Also, are there any other reasons (except no weather sealing on Sigma) why I shouldn't get the Sigma lens?
UPDATE What I meant with better performance of Zeiss is the amount of light transmitted.