There's two things going on in this thread. Some ppl overhyping the 200-500mm. And people underestemating the Sigma cause 'well it's third part, it can't be good enough'.
In the end BOTH are incredible pieces of glass (that 5 years ago, i didnt dream, think could exist). But 95% ppl still choose the Nikkor. Wich is a bit surprising imo. Especially for EU people where the nikkor is relative expensive compared to US and the Sigma is very cheap compared to US.
I used them both, at a photoday where manufacturers let you borrow and use lenses. Both have up and downsides. Both are great. Both will (if the user practises enough) yield great photo's.
Also one of the problems (seemingly) with dpr poster is that 90% is older then 35 years (please correct me on that, but most people seem crazy surprised when I say i'm 27 old). Wich means heavyness is 'pretty heavely' counted as downside. Put a younger public on dpreview, and a lot more people will not discard the Sigma so fast.
I'm lucky to be left handed (left hand is wich carries the package mostly, right hand just support on camera, bad luck do you if that is your strong arm), and to be young. And for half an hour, carrying the Sigma + d800 was no problem. 15 min of that at least where taking picture of it. Feeling was the Nikkor was much leigher. Endurance impact wise, the nikkon felt just as bulky (if you hold it out long, your muscles get a bit of wear).
Also i'm tired of the excuse 'Sigma is front heavy'. That is just a perception cause the front part is big. Look at the glass schematics pictures. The front just has 2 or 3 pieces and is for rest empty. Also the metal cover (weigh 1,8kg), is much less pronounced on the front, then on the back. And the back has a lot more glass then the front. The only reason the Sigma is front heavy is cause it's a long lens. Any 600mm (even an F10 lens) will be front heavy. That's the nature of the beast. Nature of perception. It is however not frontheavy as in front element being much heavier then the back. If i holded it on tripod food, the combo was almost completely balanced (slightly front heavy at 600mm, BACK heavy when at 150mm. If you hold it by the end of lens with left hand, then you are in for a muscle fitness marathon (perhaps another reason for heavyness perception). Hold it by the mid of lens (tripod food), and keep your elbow close to body for superior muscle support (imo).
Also from my observations:
Nikkor is purely bird lens (and wildlife). It's corners are not so good, making it a worse landscape choice.
The corners of the Sigma are quit a bit sharper according to brad (and other reviews). That is important for me, cause bird photography will NOT be my primary use of it (but rather landscape). Nobody here see that as downside wich implies most people are primary buying this lens for birding (nikkor), wich it is excellent at. For allround capability (other then being light enough to carry everywhere, but I think the nikon is still to heavy also for that), I think Sigma is better.
Indoor, wich the sun down (but light still pretty strong and active) with superior big glass parts (so lots of light coming tru, not true indoor low light scenery), the Nikkor hunted about 3-5 tims before starting to lock on (high contrast) target). Sigma never bothred to hunt, and went immediately to the target, to then micro adjust close to the target. This is with D800. D750/d4 might give nikkor an edge cause people like T O Shooter claim that the nikkor 200-500mm needs a really good AF motor to get the best out (while the Sigma seems less affected by that).
Still not purchased either, but i'm still leaning Sigma for allround capability. If i want travel lens the 70-200mm F4 (and it's range limitations) will have to do. If i buy a telezoom 500mm+ i want it to be a powerhouse.
they are too fast.
