Review of the ASP 18-200mm f/3.5-6.3D IF DC Sigma: You can’t have at All.Strengths, weaknesses, competition and pro reviews. In spite of its optical flaws, still quite respectable for an extreme zoom at this price point.
Review of the APO 100-300mm f/4D EX DG HSM Sigma: Sharp, even at f/4, excellent construction, great value for money.
Review of the ATX Pro 12-24 mm f/4G Tokina. Strengths and weaknesses, links to pro reviews. Conclusión: big bang for your buck.
What means AF-S DX IF ED D G fEE SLR APO APS-C HSM CCD? Dictionary of (digital) photography terms and abbreviations.