Feb 28 2005: Tested here at 20mm and f5.6/f11 are the following lenses:
Sigma 12-24mm F4.5-5.6 EX DG HSM [$600] aka, "Popeye"
Sigma 18-50mm F2.8 EX DC [$400]
Sigma 18-125mm F3.5-5.6 DC [$250]
Sigma 20mm F1.8 EX DG RF [$300] aka, "Bargain Bucket/El Hombre"
These 4 lenses are GOOD copies and I believe are REPRESENTATIVE of what can be EXPECTED from each lens. EACH of these lenses focus accurately and have NO problems with my 20D. Feel free to email me if you have questions or comments, and I hope this test is somewhat helpful to you.