Ultrawide mega-test: Nikon vs Canon vs Sigma

sandeep, thanks for the detailed test.

some caveats

1. as you said, sensor resolution makes a big difference. at the end of the day, right now, if you want the most detail, d800 is the way to go.  Roger from lens rental demonstrated that the tamron 24-70 vr gives higher resolution on d800 than the mighty canon 24-70 2.8 II does on 5d3.  so as you stated astutely, even after downsizing, the original resolution does make a difference.

2. Not sure if I agree about using filters. many landscape photographers dont use filters, b/c of loss of contrast, resolution, and additional flare.  I  would have left the filter out.

3.  having owned an shot extensively, both for comparison reasons and real world situations, a good copy of 16-35II, and 14-24, both on canon 5d2 and 5d3, I have a few additional observations

a: Nikon has better micro contrast, as long as its not ruined by flare (which happens very easily).  canon is no slouch, but nikon is a bit better.

b:  Canon has better performance in the corner in near field.  this is visible from f5.6 on.  Nikon does better in the far field at all f stops and focal lengths.  your test did not test for Far field corner performance except in your folliage comparison.  the reason Nikon consistently did better in folliage, is better far feild deatil.  , is it is just sharper in far field than near field, and canon is vice versa

4. I would not call 12-24 unusable, though I agree it is in a different (far below) class.  I have taken many shots with it which I have really liked, though corner sharpness has not been great.

5.  I agree with you that the Nikon 14-24 is not always the easiest landscape lens to use b/c can use filters, and it flares very easily.  as for the nikon 16-35, it has hefty barrel distortion at 16, 4.34% vs canon 3.26.  Canon 16-35 II is more of a dual purpose lens, as many wedding photographers use it, and its probably the most commonly used lens for photojournalism.  the canon has a nice VR that can be helpful in a pinch.  both very good lenses.