Sigma 17-70 "C" or 17-50 2.8 OS?

Started Jan 21, 2014 | Discussions thread
1llusive Senior Member • Posts: 1,047
Re: Sigma 17-70 "C" or 17-50 2.8 OS?

hoof wrote:

inlawbiker wrote:

Alandb wrote:

Can I ask why there is no mention of the Nikon 16-85mm? Is it thought of as a lesser lens or is it just not fast enough?

That is a fair question. I did have a 16-85mm for a while and I liked it, but the Sigma 17-70mm is about the same zoom range and a stop faster. It is very solidly built and a good lens but not worth what Nikon is asking for it in my opinion.

I've owned the 16-85 and now own the Sigma.

The 16-85 was optically fine. My issue was that the AF adjustment for 16mm was significantly different than the AF adjustment for 85mm. That meant there was no setting that ensured sharp accurate auto-focus across the zoom range. This only got worse for me when I upgraded from a Nikon D7000 to a Nikon D7100, due to the higher sensor acutance.

I switched to the Sigma to bypass this issue (primarily through the dock, though it turned out to be properly calibrated). I was pleasantly surprised to find the IQ better from about 20mm to 70mm. And the faster aperture helped me also replace a Tamron 17-50 F/2.8 VC that also had the variable AF-adjustment problem. I now pair my 17-70 with the Sigma 18-35. The combination covers all my mid-range zoom needs.

So optically, there's nothing wrong with the 16-85, other than the lens being a bit slow. My copy, however, had AF adjustment issues that were simply not worth dealing with anymore.

What good is sharp optics if you can't get reliable focus?

That's odd, my Tamron 17-50 (non-VC) seems to be spot on with my D7100. Noisy, but accurate. I contemplated selling it for the longest time, researching the Sigma 17-50 and the 17-70 among many others (Nikon and Sigma 18-35). My conclusions were:

  • Sigma 17-50 would be sharper in general vs the 17-70, with its weakness being f/2.8 (same as my Tamron)
  • 17-70 loses to the Tamron, especially at wider focal lengths, but gains 20mm on the long end, though at f/4
  • Sigma vs Tamron 17-50 may be a close call. Sigma has quiet AF, Tamron does not. However Sigma has more focusing and compatibility problems with our Nikon bodies and I didn't feel like rolling the dice on that.
  • The Nikon lenses' main appeal to me is the autofocus. However the aperture is just too slow for me.
  • I thought either would be an upgrade in autofocus. I changed my mind after noticing the much better focus performance with this lens on my D7100 over my D300, which used to frustrate me at times with all the hunting and whining in lowish light
  • Either would cost me too much money to justify

In the end I have decided I will sell my 50 f/1.8G when Tamron updates their 60mm macro with USM and stick with their 17-50 as it's actually really hard to beat. Especially for the price. I may get the Sigma Art 30mm prime eventually for a low-light normal lens but it isn't a high priority.

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