08-28-2011, 06:42 PM
Brightcolours, considering that the pictures you linked have nothing with details outside the center of the frame and have been sharpened (as you can see in the EXIF of some of them), they are ok. Good luck if you're using the Sigma and your subject is not in the center.
Here's a reminder of the performance at 300mm as tested by Photozone - Sigma on the left, Tamron on the Right:
![[Image: 8409970.png]](http://forums.ort.org.il/files/117/2578214/8409970.png)
Granted, the Sigma was tested using an 8MP Canon while the Tamron was tested using a 10MP Pentax. The more pixels there are the higher the difference between the border and center (for a given lens), yet in this case the Sigma resolving power dropped far lower in the borders than the Tamron. My experience and Photozone's tests show the same - this lens is really quite terrible for subjects that are not centered.
Aside from IQ, Sigma's poor track record when it comes to compatibility with new bodies is another reason to avoid their lenses unless they are very special. The 70-300 APO DG is nothing special. It costs more than the Tamron, and delivers less.
Here's a reminder of the performance at 300mm as tested by Photozone - Sigma on the left, Tamron on the Right:
Granted, the Sigma was tested using an 8MP Canon while the Tamron was tested using a 10MP Pentax. The more pixels there are the higher the difference between the border and center (for a given lens), yet in this case the Sigma resolving power dropped far lower in the borders than the Tamron. My experience and Photozone's tests show the same - this lens is really quite terrible for subjects that are not centered.
Aside from IQ, Sigma's poor track record when it comes to compatibility with new bodies is another reason to avoid their lenses unless they are very special. The 70-300 APO DG is nothing special. It costs more than the Tamron, and delivers less.