Which lens is sharper and would be better for a walkaround lens.
Also take pics at night parties and night functions. it would be used on D90.
Your thoughts.
The 35-70 is a push pull lens no? Just for that fact, I would say the 17-50. On top of the fact that if this is gonna be used at night parties and functions you will most likely want wider as opposed to more telephoto!
The 17-50 is really excellent but has a slow focus in a low light environment... for night parties I prefer fixed focal lengths like a 50 1.4 or 85 1.8... or one of the more expensive 2.8 AF-S zooms... The 35-70 2.8 is faster to "lock" focus than the Tamron but you need to get used to the push-pull mechanism. The front element rotates but that won't really be an issue for night photography.
The Tamron is not only inherently sharp with good color, but their VC delivers another 3, if not 4 stop shutter speed reduction for much "sharper" shots in lower light conditions. The extra zoom range makes it a better walkaround lens too.
I had a Tamron 17-50 I used on a D90 and it wasn't that great. It wasn't a 'bad' copy, but definitely not the 'best' copy either - my point is make sure you test it out. For night photos such as you describe, with or without flash, the Sigma 30mm f/1.4 is my favorite lens. It always delivers great results. 30mm might not be wide enough for you, though.
I have a 35-70, and like it a lot. You say using it at night functions, and parties. For that I would really look at maybe a 50 1.8 or 50 1.4. 85mm 1.4? Depends on your budget. You know they say the best lens for DX format is 17-55 2.8. While it might not be in your price range "right now", it could be in a few months?
I am with the other guy about primes. While I do use a Tokina 16-50 zoom I also like to have primes on me at all times. The Tokina works well when I can use flash or the lights are up but often when the lights run low and/or I am in a venue where I cant get much performance out of flash I love having a prime that can shoot well at f/2.
Although primes are great you will probably be wanting something wider than 35. In tight spaces or with a group you will need something wider.
I found that $ for $ the nikon 24 - 85 was the best walkaround (although better on an FX). Very sharp lens. PS, I have one listed on the BS .....thomas
I've a very sharp copy of the 35-70mm .. it's really nice and I shoot it alot on the D700 .. which with that setup is a bit heavy.
I also have a very sharp copy of the 17-55mm also after sending it in to Melville that I use on my D80 that I'm very pleased with .. if it were still on my D300 I'd be even happier !!