The Sigma 2x EX APO Tele Converter for Sony A mount (also known as a tele-extender) will multiply the focal length of the existing lens by 2x, and will cut back the amount of light by 2 f/stops. For example, using a 2x teleconverter with a 300 mm lens will effectively increase the focal length to 600 mm. A lens set to f/2.8 will now be f/5.6.
Compatibility for Sony a65, a77
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.