03-15-2011, 08:30 AM
Hmmm, interesting discussion. But I guess it is more important that I buy a good copy of either the Sigma or the Tamron, as a good Tamron will probably beat a bad Sigma and vice versa.
So than remains my second question: how do you test such a lens in a shop in an industry park without brick walls? My guess is f2.8, find a flat textured surface of some sort and shoot from a reasonable distance at different focal lengths and than analyse the photos in the centre, the border and the outerborder. Hopefully this will show decentering for instance. And I guess a newspaper will help to analyse focus accuracy. Is there anything you can add? Or is it the wrong set-up?
So than remains my second question: how do you test such a lens in a shop in an industry park without brick walls? My guess is f2.8, find a flat textured surface of some sort and shoot from a reasonable distance at different focal lengths and than analyse the photos in the centre, the border and the outerborder. Hopefully this will show decentering for instance. And I guess a newspaper will help to analyse focus accuracy. Is there anything you can add? Or is it the wrong set-up?