Sigma TC-20 II L Mount Teleconverter Key Features Superb optical performance For SIGMA L Mount Lenses 2x magnification Fully functioning AF Dust and splashproof design Why buy the SIGMA TC-20 II L Mount Teleconverter? The SIGMA TC-20 II Teleconverter has been designed for SIGMA L Mount Lenses. The TC-20 II expands your focal length by 2x. The excellent optical capabilities of this teleconverter replicate that of the popular Art and Sport series of lenses from SIGMA. It has been designed for mirrorless cameras and maintains AF performance, unaffected by the F-number. A splash and dustproof build make them long life and ideal for shooting in challenging conditions. Whats the advantage of a Teleconverter? These light, compact add ons for your lens give you ultra-telephoto angles without the need for a large lens. Perfect for the travelling photographer, or those with a more limited budget in mind!