Description The dedicated 1.4x APO Teleconverter features a high performance 5 element/3 group optical design, and it is optimized for use with long telephoto and telezoom lenses. The high performance optical characteristics of these teleconverters maintain the optical performance of the compatible lenses with which they can be used. Using 10-pin electrical interfaces, there is no loss of autofocusing speed when these teleconverters are used with compatible H.S.M. type lenses for Canon, Sigma, and now current Nikon AF cameras (except N60/F60 models). They are ideally suited for use with the 70-200mm F2.8 APO EX HSM zoom lens; providing normal exposure and autofocus function, while maintaining its high optical performance.
- The Sigma 1.4x DG EX APO Tele Converter (also known as a tele-extender) will multiply the focal length of the existing lens by 1.4x, and will cut back the amount of light by one f/stop. For example, using a 1.4x teleconverter with a 300 mm lens will effectively increase the focal length to 420mm. A lens set to f/2.8 will now be f/4.
- Sigma APO Tele Converter 1.4x and 2x are dedicated teleconverter lenses. Due to the high optical quality of this teleconverter, this item will only fit and work with a select list of lenses
- The DG denotes an added coating that achieves the best color balance while cutting down on ghosting caused by reflections from the digital image sensor.