Neal Vaughan , Jul 26, 1999; 12:42 a.m.
Sigma and Tamron are two completely different companies, with completely different product lines. Not connected at all. Ritz Camera, as a result of a contract with Sigma, sells the Quantaray optics exclusively. The lenses are always the same optically as Sigma's, but cosmetically, they are a little bit different to distiguish them from Sigma's line. There are wide differences between the quality of differnt lenses from just one of the manufacturers. Both Sigma and Tamron made low-level lenses made for consumers that are decent and very cheap, and both of them also make pro-level lenses that can compete with the camera makers own lenses. You cant really say that one brand is better than another in this case, its kinda impossible because of the variations in lenses. Quantaray lenses, on the other hand, are usually Sigmas's non-professional lenses. They have about 10 or so lenses overall, but none are truly professional.