[Brightcolours]

[quote name='boren' timestamp='1314528620' post='11102']

For both the Tamron and the Sigma shots I used a steady tripod and 2" timer (with MLU). The Sigma was consistently less sharp than the Tamron, across all apertures.



Since Photozone tests also show that the Tamron is much sharper than the Sigma, they too must have had a bad copy of the Sigma and a great copy of the Tamron, right? <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/wink.gif' class='bbc_emoticon' alt='' />







You must be joking. What lens isn't sharp at 85/6.3? The Tamron is razor sharp at this focal-length and aperture, practically rivaling prime lenses, but at 300mm wide-open it's a different story. It's only usable, which is more than I can say for the Sigma.

[/quote]

The photozone tests do not show the Tamron to be "much sharper", in fact they show the center at 300mm to be the same sharpness. So yes, like I said, you must have had an exceptionally bad copy of that Sigma. Something is clearly wrong there.



Sorry about the crop above, I mistook it for a 300mm example.



Here 300mm full size samples, to show that your sigma result is somehow severely messed up (be it camera shake (looks like it) miss-focus or a damaged lens).

300mm f5.6 (wide open) with the Sigma APO Macro version:

http://www.flickr.com/photos/tabor-roeder/5034522759/sizes/o/in/photostream/

http://www.flickr.com/photos/sara-net/5249711665/sizes/o/in/photostream/

http://www.flickr.com/photos/oliver1978/2442764463/sizes/o/in/photostream/

http://www.flickr.com/photos/romainpampelonne/3306174431/sizes/o/

http://www.flickr.com/photos/sara-net/5249711861/sizes/o/



Hopefully I didn't include any non-APO sample in there <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/tongue.gif' class='bbc_emoticon' alt='' /> )