The SIGMA TELE CONVERTER is developed exclusively for the new lens lines. By mounting it in between a telephoto lens and a camera, the offered magnification of focal length of TC-1401 is 1.4 times and that of TC-2001 is 2 times respectively.Both models incorporate SLD (Special Low Dispersion) glass elements that offer excellent aberration correction. It is exceptional for a lens accessory to use one of the best glass materials, yet this is because SIGMA is seeking for the best image quality, and it is necessary to meet the new “SGV” standards.It is suitable for professional use since its durable construction is dust and splash-proof. It is compact and light, and provides easy extension of focal range.TC-1401 incorporates 1 SLD (Special Low Dispersion) glass element, and TC-2001 carries 2. By minimizing chromatic aberration effectively, it has achieved very good optical performance, thus it is possible to maintain the optical quality of the original lens.Its power distribution is designed for lenses of large diameter. Without affecting the lens performance, it offers stable image quality until corners. The rich peripheral brightness enables shooting quality images at every focal length.