A few days ago, Sigma launched a new version of its prize winning standard zoom lens. Equipped with HSM, faster aperture and OS, Sigma is leveling the playing field against the original manufacturers. This lens is aimed squarely at the new Canon 15-85 f3.5-5.6 IS and the Nikon 16-85 f3.5-5.6 VR. Since the new Canon has recently been receiving favorable reviews, I would like to do a rough comparison in case anyone is deciding between these two lenses:
For the Canon 15-85:
- The 15-85 is a very sharp lens, as compared to similar lenses and very comparable to its Nikon counterpart (finally) while having a marginally wider zoom range. From the manufacturer published MTF figures, I think the 15-85 could be slightly sharper than the new 17-70 OS wide open. Currently measured figures shows the 15-85 to outperform the current 17-70 marginally.
- The 15-85 has a wider range (24-136 equiv). As a walkabout lens it is about as wide and as much tele as you need.
- The 15-85 seems to support MF better with a smooth focus ring. The 17-70 was thought to be a little stiff
- Being a Canon lens, its profile is available on DPP, so auto correction of vignetting, CA, distortions can be done at a click of a button.
For the Sigma 17-70 OS:
- The 17-70 is faster(2.8-4.0) than the 15-85, its max tele aperture is slightly bigger than the original 17-70 (2.8-4.5).
- From the charts, the 17-70 seems to show an improvement in terms of sharpness when compared to the 17-70 and could be closer to the 15-85. Actual measured results could be different though. We will never know until more data is available.
- The 15-85 is considerably more expensive. as an indication, on Amazon, the 15-85 is about US$700 while the 17-70 is about US$450.
- Other considerations include: Size/weight, Inclusion of a hood
- Vignetting performance is likely to be better than the 15-85 at certain apertures, but as mentioned, since the Canon lens profile will be available on the DPP, this is easily corrected.