| Introduction | Measurement | Comparisons | Conclusion |
Here are three possible candidates for “standard” zoom:
Their Scores:
On the face of Sharpness the Tamron looks good: 10P-Mpix is just higher than the Sigma.
Both the independent lenses beat the Canon which scores just 7P-Mpix.
Tamron lens does do very well, but it is far less consistant: at its best it just beats the other two but wide open it has to be at 50mm to win and stopped down it really falls apart.
The Sigma on the other hand maintains a similar result throughout the range of focal lengths and does better at retaining quality stopped down.
The DxOMark choice:
The first point is that the Canon is not as good. It’s slower by a full stop over the Sigma and it lacks the sharpness of the other two.
The Tamron will probably produce the nicest results at its optimum aperture and focal length but the Sigma will come close and just beats the Tamron overall.
Additionally the Sigma is cheaper, lighter by 100g, zooms out to 70mm instead of 50mm and offers a greater degree of magnification for Macro: 1:2.9 against the Tamron’s 1:4.8.
It is good to see when companies introduce an updated version of an existing product and it shows a real improvement. Sigma has had a 17-70mm macro zoom lens in its range since 2006. Initially it had no image stabilisation and the AF was not Hyper-Sonic, but physically it looked very like the new version. Version two had the IS and HSM but was quite a bit heavier. The progress in quality has been good, P-Mpix has risen by one point each time and the overall score has climbed two point each time. The original version had less distortion than the subsequent models but the distortion is really not a serious issue with this lens anyway.
A final brief comparison with the Flagship ‘standard’ APS-C zoom lenses from Nikon and Canon, admittedly these are really marketed to a different sector but the figures are quite sobering. Both companies produce f2.8 lenses with a 17-55mm range, both have a price tag twice that of the Sigma, both are much heavier and larger (quite understandably given their faster aperture). However the Sigma from a quality point of view is as good as the Canon and better than the Nikkor. If it is not essential to have the fixed f2.8 aperture then the Sigma lens is really the best value here.
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Added by Mato34 |
March 03
Regarding three versions of Sigma 17-70
I'm a Nikon user, and got my Sigma 17-70/2.8-4.5 (first version) when bought my D300.
I was really happy and amazed of how sharp could be that lens, and even I got the Nikon 16-85 VR only to sell it some time later because I liked way more the microcontrast and clarity of the Sigma. Then the 17-70 OS version showed up, and being so happy with the first version I bought this OS one. But I was shocked because results weren't so good. Tried three copies, and below 35-50 mm field curvature was really a problem even at f/8: focus on the center and get blurried sides, focus on sides and get blurried center. It was so heavy that I almost couldn't believe it, but I was seeing it... A couple of years ago I could test a new sample from a friend that didn't show that field curvature (???), but anyway results weren't that good, my old 2.8-4.5 was still better on corners closing at f/5.6 than the OS at f/8. And now here comes this C version, and again I'm quite excited about it. Well, not that much now, because when comparing measurements of the three versions at 17 and 24 mm I can see that the first one still delivers sharp corners, but not so the OS nad C versions. Can wait for real samples, but I have liked to see something different at the wide end in the corners. Saludos! Reply |
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