All, I took some time and for the second time in my life set up a test with my own lenses and a borrowed Canon zoom. Also a 1.4x Canon v. Tamron. I made slides on Kodak Etachrome 200 of a large newsprint page and projected them at 30x40. I used 70/135/200 using F2.8 and F8 apertures. Here is the basic findings. Subjective? Yes, but this is closer to real world than most other tests. The Sigma 70-200 v. Canon 70-200mm. At 70 & 135mm there was a slight edge to the Canon only at F2.8. At all other settings they looked identical. The Canon had a more neutral color while the Sigma a very very slight warmth to it. At 200mm you could not tell them apart. I then used the 1.4x from Canon (original) and my Tamron SP 1.4x. The Canon was slightly sharper on the Canon lens but barely and certainly nothing worth 2x the price unless you expect to make 30x40 or 40x60 prints often. I could not use the Canon on the Sigma because the protruding element on the Canon 1.4x did not allow it to work with the Sigma lens. I also ran a comparison of the 135mmF2L and 28-135mm IS lens both at 135mm and compared it to the Canon and Sigma zoom. The 135mm F2L was sharper especially at F8. My surprise was the IS zoom at 135mm at F8 was also very very good. Not as good as the 135mmF2L but pretty close to the bigger zooms. Good contrast. While it would not make me sell off my 135mm F2L it did better than I expected. I did test the 100-400mm zoom but have not done a full comparision yet. Conclusion - All do a good job. My results seem to coincide with the Photodo test results so I will continue to use that site and their tests as a benchmark. BTW, the results also agree with Pop Photo test. While I know many do not like their testing they seem to hold up. Sorry that I did not test bokeh. This was just resolution of the lenses I was curious about. Also, note that AF is faster on the Canon 70-200mm than on the Sigma but not a dog by any means. If you can live with that you can save a bit. Peter K Guess I will keep my Sigma. * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
