Anyone using the new Sigma 70-200 OS?

Started Aug 5, 2010 | Discussions thread
mmullen Veteran Member • Posts: 4,285
Re: First in-depth review!!!

Robert Krawitz wrote:

As I mentioned in another thread where we've had a similar discussion, I don't believe that that's true at medium distances and above. Compare (link clipped) (with the Sigma) -- at perhaps 40', there doesn't appear to be more than 1% difference or so.

That very well could be - I don't think we disagree (significantly) on the focal length at the 40 foot focus distance. What I'm saying is that the Sigma is not anywhere near 200mm for most of the range on the focus scale. I guess our only disagreement is what "medium distances" entails. To me, 40 feet is very close to infinity focus. I'm not sure how the focus scale on the Sigma is setup but, looking at my Canon Mk II I see the mid-point (between infinity and 1.2 meters) is 2 meters (or just over 6 feet). That's just the way focus scales work (focus changes more dramatically at closer distances) so I assume the Sigma is similar. And focus breathing on the Sigma is very noticeable begining at distances well over 6 feet. But it is a gradual process so at 10 feet the actual focal length (when the zoom ring is set to 200mm) is probably about 160mm and when at 15 feet it's probably about 170mm. But at 4.9 feet the maximum focal length of the Sigma is 140mm and we know this because it can be calculated by the figures published by Sigma (maximum magnification and closest focus distance). But 40 feet is very similar focus to infinity and while I think your estimate of 1% less than the Canon is slightly optimistic, I agree with you that it is probably less than a 5% difference. That translates to slightly less reach at a distance (which means slightly more cropping when focal length limited).

My observation -- and I don't have a lot of experience handling relatively heavy lenses yet (but I've used other IS lenses) -- is that the Canon mkII IS is probably better than the Sigma, but the difference is not overwhelming and with both lenses it's still necessary to use good handheld technique.

That would not surprise me - Canon is the company that developed the first optical image stabilization system back in the 80's and they have been spending large sums of R&D funds developing it ever since. I would be surprised if Sigma had caught up to them in terms of stabilization technology.

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Mike Mullen

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