Nikon 16-85mm or Sigma 17-70mm for travel?
I'm going to New york City next week and I would like to purchase a zoom lens to take pictures of the city. I've noticed that the Nikon is 3.5 aperture and the Sigma is 2.8. The sigma is cheaper, but I really just want to get the better lens out of the two. And Do you think this is a good zoom lens for travel?
The sigma starts at f2.8 but goes to f4. I'd be happy with a nikon 18-105 and a 35mm f1.8 if I wanted to travel light.
Nikon does have a higher aperature but is a far better lens and also has a wider range. If you are shooting during daytime, the higher aperature would not matter, only during darker shooting. I have not had the best results with sigma lenses in the past. My suggestion would be the Nikon.
The Sigma is only f/2.8 at the widest setting and it produces some vignettes and soft edges there. Ideally you'd be better to use it stopped down anyway.
Travel lenses to be honest normally cover a bigger range. Something like a 18-200 or 28-300 or smaller 24-105 are normally called travel lenses.
For city scape, buildings, streets, etc I think I'd prefer a fast 35mm (around 24mm for an APS-C sensor) or similar but of course you're limiting your range.
In my dream world I'd take a tilt/shift lens!
The last time I visited Manhattan, I carried an AF-S 12-24 mm wide angle zoom and AF-S 18-200 mm VR. The combination was rather amazing although I used the 12-24 mm about 90% of the time
In your case, since you probably already have an 18-55 mm, I would suggest you look at the new 10-24 mm lens to get brilliant shots in the city and use your 18-55 mm for shooting group shots and portraits of your friends.
As mentioned, generic lenses have many compromises to keep the costs down and profits up. For this reason, those of us who are professional, advanced amateurs or plan on keeping lenses for a few decades only buy OEM lenses.
The 17-70mm has a very slight advantage in terms of aperture, but it's not enough to make me consider it over the Nikon. The Nikon has better build, better af, and better overall image quality, and also has additional reach in both the wide end and the telephoto end.