As always when buying third party lenses there are doubts about the quality of the lens itself. The fact that third party lenses are also very reasonably priced sometimes adds to the confusion, as we all like to believe that "you get what you pay for". However, this Sigma lens ultimately surprised me and cleared all my doubts. Not only is this lens the widest straight lens currently available, but it's also remarkably sharp and well built. The HSM motor is very quiet and fast, focusing even in low light. Although the lens is large, it is actually quite light and not difficult to carry and use all day. Well, compared to Nikon, this lens has some compromises, namely aperture (F/2.8). compared to f/4.0-5.6) and of course the Nikon is said to be weatherproof. However, unless you use this lens for astrophotography, the aperture of this lens doesn't matter. I have used this lens on many trips to Peru and Ladakh (J&K, India) and also extensively in New York, aperture has never been a problem as I always tend to close down. But even wide open, the lens is sharp enough, and stopping down just makes it better. One of the most amazing aspects of this lens is that it has almost no distortion of any kind! I was really amazed to see this as it is very untypical for a wide angle lens. However, it has a lot of vignetting on FF cameras, but this is easily fixed in post. The lens also does not show a CA. Overall I highly recommend this lens, especially compared to the V2 which seems to have more distortion. For the price you're paying, this isn't a problem with a Nikon lens.
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